Pharmaceutical excipients MANIK

Md. Imran Nur Manik
Lecturer
Department of Pharmacy
Primeasia University

Md.
Imran
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Pharmaceutical Excipients
Prepared By: Md. Imran Nur Manik; M.Pharm. (R.U.) Page 1
manikrupharmacy@gmail.com; Lecturer; Department of Pharmacy; Primeasia University.
Introduction
Pharmaceutical dosage forms contain both pharmacologically active compounds and excipients added
to aid the formulation and manufacture of the subsequent dosage form for administration to patients.
Definition
The word excipient is derived from the Latin excipere, meaning 'to except', which is simply explained
as 'other than'. Pharmaceutical Excipients are substances other than the active medicament (s) which
are included in the manufacturing process or are contained in the finished pharmaceutical product
dosage form.
Role of excipients/Necessities of excipients/Purposes of excipients
Excipient play a wide variety of functional roles in the pharmaceutical dosage form including
1. Modulating the solubility and bioavailability of the active pharmaceutical ingredients.
2. Modulating immunogenic response of active ingredients.
3. Maintaining the pH and /or osmolality of the liquid dosage form.
4. Improving dosing compliance (to give a particular shape and to improve palatability, elegance of
the formulation).
5. Increasing the stability of the active ingredient in the dosage form including protection from
degradation/ denaturation.
6. Preventing aggregation and dissociation of different molecules e.g. Protein and Polysaccharides.
7. Providing bulk to the formulation.
8. Helping the active ingredients to maintain preferable polymorphic form or conformation.
9. Conferring a therapeutic enhancement on the active ingredient in the final dosage form, such as
facilitating drug absorption, reducing viscosity, or enhancing solubility.
10. Aiding in handling of “API” during manufacturing.
11. Facilitating administration of the drug by the intended route.
12. Facilitating drug absorption or solubility and other pharmacokinetic considerations.
13. Ensuring a robust and reproducible physical product.
Classification of Excipients
Excipients are classified by the functions they perform in the pharmaceutical dosage form. Principle
classes of the excipients are as follows.
1. Diluents (Bulking agents, Fillers)
2. Binder
3. Disintegrant
4. Lubricants
5. Glidant
6. Sweetening agents
7. Acidifying agents,
8. Air displacement agents,
9. Alkalizing agents,
10. Antifoaming agents,
11. Anti-microbial agents,
12. Preservatives,
13. Anti-oxidants,
14. Buffering agents,
15. Chelating agents,
16. Colors, complexing agents,
17. Emulsifying agents,
18. Flavouring agents and perfumes,
19. Humectants,
20. Ointment base,
21. Solvents & Co-Solvents,
22. Stiffening agents,
23. Wetting and solubilizing agents,
24. Viscosity imparting agent.

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Properties of an ideal excipient
Excipients must have such quality that they will increase the stability of the product.
1. They should be compatible and have no interaction with the active ingredient in the preparation.
2. They must not adversely affect the product.
3. They should be pharmacologically inert.
4. They should be nontoxic, nonirritant in the concentration administered to the patient.
5. They should be nonvolatile.
6. They should be physically and chemically stable throughout the shelf life of the product.
7. They should be effective in low concentration over a wide range of pH.
8. They should be soluble in water as well as oil & fat.
9. They should be colorless, odorless and tasteless.
10. They should be cheap and readily available.
Excipients can also be useful in the manufacturing process, to aid in the handling of the active substance
concerned such as by facilitating powder flowability or non-stick properties, in addition to aiding in vitro
stability such as prevention of denaturation or aggregation over the expected shelf life.
Why excipients are important in a drug product?
Excipients are important for many reasons. Such as
1. It comprises the product delivery system i.e. transport the active drug at the site in the body
where the drug is intended to exert its action.
2. The excipients will keep the drug from being released too early in the assimilation process, in
the place where it can damage the tissue or can create gastric irritation or stomach upset. e.g
Diclophenac-Na (Coating is applied for this problem)
3. It helps the drug to disintegrate into particles small enough to reach the blood stream more
quickly. e.g. Disintegrating agents (Povidone).
4. Some of the excipients protect the stability of the product so that it will act with the maximum
effectiveness at the time of use. e.g. Stabilizers (Antioxidants ,Preservatives)
5. Some excipients aid in the identification of the product. e.g. Coloring & Flavoring agent
6. Some excipients are also simply used to make the product tasty and look better. This includes
patient‟s compliance especially in children.
7. In many product excipients makes up the total dosage form. e.g. Diluent.
Advantages and uses of excipients
The followings are important uses and advantages of excipients.
1. Excipients are used to give a particular size and shape of the medicaments. e.g.
Suppositories (Base).
2. To make the medication suitable for administration. e.g. Syrup, Suspension.
3. To protect the medication from gastric environment. e.g. Coating of tablet.
4. To mask unpleasant taste and odor. e.g. Sweetening agents & Flavoring agents.
5. To reduce the adhesion between powdered granules and punch face. e.g. Glidants.
6. To increase the stability of the product. e.g. Stabilizers.
7. To improve the appearance of the product. e.g. Coloring agents.

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Stabilizers
Stability: Stability of pharmaceutical product may be defined as the capability of a particular formulation
in a specific container &closure system to remain within the physical, chemical, microbiological,
therapeutic and toxicological specifications.
The substances which are used to control these stabilities are known as stabilizers.
The most important stabilizers are,
1. Antioxidants and
2. Preservatives.
Antioxidant
An antioxidant is a molecule capable of inhibiting the oxidation of other molecules. Antioxidant added
to pharmaceutical formulation to prevent the oxidative degradation of the drug in the presence of
oxygen or peroxides.
They act by blocking an oxidative chain reaction. The antioxidants have great affinity for oxygen and
when they are added to formulation they compete for it affording protection to other oxygen sensitive
drugs.
Some antioxidants are:
1. Quinol group
Hydroquinone
Tocopherols
Hydroxychromans
2. Catechol group
Catechol
Pyrogallol
Gallic Acid
Ethyl Gallate
3. Nitrogen containing Substance
Alkanolamine
Diphenylamines
Casein
Edestine
4. Sulphur containing Substance
Cysteine Hydrochloride
5. Monohydric Phenol
Thymol
Classification of antioxidant
1. On the basis of the function antioxidants are two types. They are,
a. Primary antioxidants/ true antioxidants.
b. Synergists.
Primary antioxidant: Primary antioxidants or true antioxidant act by breaking the antioxidant chain
usually by interfering with the propagation step of autoxidation process.
e.g., Tocopherol (Vitamin E), Gallic acid, Butylated hydroxyl anisol (BHA), Butylated hydroxyl tolune
(BHT) and nordihydroguaiaretic acid (NDGA).
Synergist: The synergist class of antioxidants has little inherent anti-oxidation properties. They act by
enhancing the action of true antioxidants usually by regenerating them or by removing pro-oxidant trace
metals known to catalyse the oxidative degradation.
e.g. EDTA and its Ca & Na salt, Citric acid, Glycerine, Propylene glycol, Polyethylene glycol etc.
2. On the basis of solubility antioxidants are two types. They are,
a. Water soluble antioxidant.
b. Oil soluble antioxidant.

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Water soluble antioxidant: The main classes of water soluble antioxidants are sulfurous acid salts,
ascorbic acid isomers and thiol derivatives.
The important characteristics, storage condition and uses of members of this class are tabulated below.
Compound Solubility pH Drugs for which suitable Conc. Storage
Sodium
bisulfite
Soluble in water,
slightly soluble in
alcohol.
1-5 Steriods, antibiotics,
adrenergics,procainamide,
dextrose morphine
0.05%
Away from
light, Below
40◦C
Sodium
metabisulfite
Soluble in water,
slightly soluble in
alcohol.
acidic epinephrine
0.025-0.1%
Away from
light, Below
40◦C
L-Ascorbic
acid
Soluble in water
and alcohol
3-6 Epinephrine, Ferrous
sulfate 0.2-0.5%
Air tight,
away from
light.
Thioglycerol
Slightly soluble in
water, miscible with
alcohol
3.5-7 Streptomycin sulphate,
reserpine, Methyl-dopa,
promethazine
0.1-0.5%
Air tight,
cool place
Oil soluble antioxidant: The oil soluble antioxidants are often needed for the protection of fatly foods
and cosmetics. In the pharmaceutical field, formulations like ointments, oily injections etc. containing g
oxygen sensitive drugs may require protection by anti-oxidants.
Some of the oil soluble antioxidant properties are given below.
Compound Solubility Materials for
which suitable
Conc. Storage
Butylated hydroxyanisol (BHA)
& Butylated hydroxytoluene
(BHT)
Soluble in alcohol,
propylene glycol
Fatty
formulations 0.005-0.02%
Normal
condition
Propyl gallate Soluble in alcohol,
slightly soluble in water.
Thiothixene 0.01-0.1% Normal
condition
Tocopherols Soluble in alcohol Vitamin A 0.05-0.75% Air tight,
away from
light.
Properties of Antioxidants (Choice of antioxidants)
An antioxidants in addition to their antioxidative properties must possess certain other desirable features
indicated below for use in the pharmaceutical preparation.
1. Ought to dissolve readily in the substrate.
2. It should be nontoxic and free from irritant and sensitizing qualities.
3. Must not interfere with the organoleptic properties of the product.
4. It should be compatible with formulation ingredients and packaging material.
5. Should be thermo stable and effective against a wide range of pH.
6. Effective at a low concentration.
7. It should not possess objectionable color, odor and taste.
8. Reasonable cost.

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Some commonly used drugs sensitive to oxidation
Drugs that are sensitive to oxidation are,
1. Ascorbic acid (Vitamin C)
2. Chlorpromazine.
3. Cyanocobalamine (Vitamin B12)
4. Gentamicin.
5. Heparin.
6. Hydrocortisone.
7. Resorcinol.
8. Riboflavin (Vitamin E)
9. Streptomycine.
10. Methyldopa.
11. Morphine.
12. Penicillin.
13. Tetracycline.
14. Thiamine (Vitamin B1)
15. Vitamin A,D and E
16. Paracetamol
Preservatives
Most pharmaceutical formulations are liable to microbial growth and therefor have to be properly
preserved.
A preservative is a substance which is added to pharmaceutical formulation to prevent or inhibit the
growth of microorganisms in the preparations in order to prolong their shelf life.
Preservatives are used in multi-use cosmetic/pharmaceutical products (including paediatric formulations)
to prevent an increased risk of contamination and proliferation by opportunistic microbes (from
excipients or introduced externally), that would result in potential health issues.
Ideal properties of preservatives
In concept, the preservative system protects the product against microbial proliferation but does not
compromise product performance. In practice, the preservative selected should have the following
properties.
1. Exert a wide spectrum of antimicrobial activity at low inclusion levels.
2. Maintain activity throughout product manufacture, shelf life and usage.
3. Not compromise the quality or performance of product, pack or delivery system.
4. Not adversely affect patient safety or tolerance of the product.
5. It should be chemically compatible with other ingredients of the formulation.
6. It should be nontoxic and non-sensitizing.
7. It should be soluble in aqueous phase when used in emulsions.
8. It should be odourless, tasteless, and should not impart colour in the formulation.
9. It should be stable and effective over a wide range of pH.
10. It should be of low volatility to ensure that loss does not occur during storage.
Examples: Methyl paraben and Propyl paraben 0.1-0.2%,
Ethyl parabens, Propylparaben, Butylparaben,
Benzoic acid and benzoates 0.1-0.2%,
Sorbic acid and its salts 0.05-0.2%,
Alcohol 15-20%,
Benzalkonium chloride 0.004-0.02%,
Phenol 0.2-0.5%.

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Q. Define combine preservative. Why more than one preservative are used in pharmaceutical
formulation?
The use of two or more preservative collectively known as combine preservative.
No single preservative possesses all the ideal properties. Sometime a single preservative is not enough
or not have the ability to kill or inhibit the growth of microorganism. Therefore it becomes necessary to
use a combination of preservatives to prevent the growth of microorganisms. These days a combination
of two or more preservatives is more in fashion, because such combinations give a broader spectrum of
anti-microbial qualities.
e.g., 0.1- 0.2% Methyl paraben and Propyl paraben which are oil and water soluble respectively used
due to their synergist effect in combined form.
Some Specific Preservatives
Benzoic acid and benzoates
1. Simple aromatic acid.
2. Use as a preservative for food, drug, cosmetics etc.
3. Concentration 0.1%.
Parahydroxybenzoates
1. Use for the preservation of food and drug.
2. Various ester of p-hydroxy benzoic acid having methyl, ethyl propyl and butyl radicals are marketed
by different forms under names such as Nipase ceries paraben etc.
3. Concentration 0.005-0.05%
4. Powerful preservative.
5. The esters are considered to be 2-3 times effective as benzoic acid.
6. The different ester may have different action against different classes of microbes. For instance, a
methyl ester is considered to be more effective against mould. Propyl ester is so against yeasts.
Phenyl mercuric nitrate & other salt
1. Low concentration as 1 in 1,00,000.
2. Use for cosmetic.
3. It is recognized preservatives of pharmaceutical product for parental use.
Phenol
1. Classical germicide.
2. Use in lotion and other preparation for internal use.
3. Used in particular products packed as multiple doses in concentration of 0.5%
Dichlorophen
1. Fungicide and bactericide.
2. Use for preservation of natural fiber like cotton and wool.
3. Use as an ingredient for hair tonic and athletes.
4. It is rather tonic and not use in pharmaceutical preparation as preservatives.
Formaldehyde
1. Good preservatives for different kind of material.
2. It is not use in pharmaceutical preparation as preservatives.
3. Is has strong pungent and irritant properties.

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Mode of Action
Preservatives interfere with microbial growth, multiplication, and metabolism through one or more of
the following mechanisms
• Modify cation of cell membrane permeability and leakage of cell constituents (partial lysis)
• Lysis and cytoplasmic leakage
• Irreversible coagulation of cytoplasmic constituents (e.g., protein precipitation)
• Inhibition of cellular metabolism, such as by interfering with enzyme systems or inhibition of cell wall
synthesis
• Oxidation of cellular constituents
• Hydrolysis
A few of the commonly used pharmaceutical preservatives and their probable modes of action are
presented in following Table
Preservative Probable modes of action
Benzoic acid, boric acid,
p-hydroxybenzoates
Denaturation of proteins
Phenols and chlorinated phenolic compounds Lytic and denaturation action on cytoplasmic membranes and
for chlorinated preservatives, also by oxidation of enzymes
Alcohols Lytic and denaturation action on membranes
Quaternary compounds Lytic action on membranes
Mercurials Denaturation of enzymes by combining with thiol (-SH) groups)
Ointment Bases
Ointments are greasy, semisolid preparations, often anhydrous and containing dissolved or dispersed
medicaments.
The ointment base is that substance or part of an ointment, which serves as a carrier or vehicle for the
medicament.
Properties of an ideal ointment base
An ideal ointment based should have the following criteria.
1. It should be inert.
2. It should be stable.
3. It should be smooth.
4. It should be compatible with the skin.
5. It should be non-toxic, non-irritating and nonvolatile.
7. It should have low melting point.
8. It should release the incorporated medicament readily.
Since there is no single ointment base available which possesses all these qualities, therefore it becomes
necessary to use more than one ointment base in the preparation of ointments.
Classification of ointment base
The ointment bases are classified as follows:
1. Oleaginous bases or fatty bases
2. Absorption bases
3. Emulsion bases
4. Water soluble bases.
1. Oleaginous Bases: These bases consist of water insoluble hydrophobic substances e.g. oils and fats.
The most important are the hydrocarbons. i.e. mineral oil, petrolatums and paraffins. The animal fat
includes lard. The combination of these materials can produce a product having desired melting point
and viscosity.

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The oleaginous bases are decreasing in favour due to the reasons described below.
1. They are greasy.
2. They are difficult to remove both from skin and clothings.
3. The release of medicament is not certain.
4. If some animal fat is included it may get rancid.
5. Fatty mixture bases prevent drainage on oozing areas and also prevent evaporation of cutaneous secretions
including perspiration. The water retention increases the heat in the particular areas.
Hydrocarbon Bases
I. Petrolatum (Soft Paraffin): It is a purified mixture of semisolid hydrocarbons obtained from petroleum.
There are two varieties of soft paraffin, one is yellow soft paraffin and the other is white soft paraffin.
Yellow soft paraffin is a pale yellow to yellow translucent soft mass, free or almost free from odour and taste. It
has a melting point of 38°C to 56°C.
White soft paraffin is obtained by bleaching yellow soft paraffin. It is a white translucent tasteless mass and is
odourless when rubbed on the skin. It has a melting point of 38°C to 56°C. White soft paraffin is used when the
medicament is while or colourless.
Both yellow and white soft paraffins are used and have no noticeable action on the skin and are not absorbed.
Thus they are suitable for epidermal type of preparations. Because of hydrophobic nature, aqueous liquids
cannot be mixed with it but sometimes wool fat and waxes are included to incorporate aqueous liquids in it.
II. Hard Paraffin: It is a purified mixture of solid hydrocarbons obtained by distillation from petroleum or
shale oil. It is a colourless or white translucent, odourless, tasteless mass and is used to harden or stiffen
the ointment bases.
III. Liquid Paraffin: It is also known as liquid petrolatum or white mineral oil. It consists of a mixture of
liquid hydrocarbons and may be obtained from petroleum by distillation.
Liquid paraffin varies in composition according to the source of the petroleum. It is a colourless, transparent,
tasteless and odourless oily liquid. It is insoluble in water and alcohol but soluble in ether and chloroform.
It is used along with hard paraffin and soft paraffin to get a desired consistency of the ointment. It is also used to
levigate the substances insoluble in it.
2. Absorption base
The term absorption is used to denote the hydrophilic characters of the base. These are generally
anhydrous bases which can absorb a large amount of water but still retain their ointment like
consistency.
Generally, they are anhydrous vehicles composed of a hydrocarbon base and a miscible substance with polar groups
that functions as a water-in-oil emulsifier, e.g. lanolin, lanolin isolates, cholesterol, lanosterol and other sterols,
acetylated sterols, or the partial esters of polyhydric alcohols such as sorbitan monostearate or mono-oleate.
The following are some of the absorption bases used.
A. Wool Fat: It is also known as anhydrous lanolin. It is the purified anhydrous fat like substance
obtained from the wool of sheep. It is practically insoluble in water but can absorb about 50% of its
weight of water. Due to its sticky nature it is not used alone but is used along with other bases in the
preparation of a number of ointments.
B. Hydrous Wool Fat: It is also known as lanolin. It is the purified fat like substance obtained from wool
of sheep. It is a yellowish white ointment like mass with characteristic odour. It is insoluble in water but
soluble in ether and chloroform.

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C. Wool Alcohol: It is obtained from wool fat by treating it with alkali and separating the fraction
containing cholesterol and other alcohols. It contains not less than 30% of cholesterol. It is used as an
emulsifying agent for the preparation of water in oil emulsions and is used to absorb water in ointment
bases. It is also used to improve the texture, stability and emollient properties of oil in water emulsions.
D. Bees Wax: It is purified wax obtained from the honeycomb of bees. It is of two types: (a) yellow bees
wax and (b) white bees wax obtained by bleaching and purifying the yellow bees wax. Bees wax is used
as a stiffening agent in pastes, ointments and other preparations.
E. Cholesterol: It is widely distributed in animal organisms. Wool fat is also used as a source of
cholesterol. It is used to increase the incorporation of aqueous substances in oils and fats.
Advantages of Absorption Bases
1. They are compatible with majority of medicaments.
2. They are relatively heat stable.
3. These bases may be used in their anhydrous form or in emulsified form.
4. They can absorb a large quantity of water or aqueous substances.
5. They can be more easily removed from the skin in compared to the oily bases.
Disadvantage of Absorption Bases
1. These bases possess the undesirable property of greasiness.
3. Emulsion Bases
Emulsion bases are semi solid emulsions having cream like consistency. These are of two types: oil in
water or water in oil emulsions. Examples of emulsion bases include hydrophilic ointment, rose water
ointment and vanishing creams.
Some additional amount of water can be incorporated in both the types and still retain soft cream like
consistency. The oil in water type emulsion bases are more popular because they can be easily removed from the
skin or clothings by washing with water. The water in oil emulsion bases are greasy and sticky, therefore they
are difficult to remove from the body and clothings. Examples of emulsion bases include hydrophilic ointment,
rose water ointment and vanishing creams.
4. Water Soluble Bases
Water soluble bases contain only the water soluble ingredients and not the fats or other greasy
substances that is why sometimes they are known as greaseless bases. They differ from emulsion bases
that the latter contain water soluble and water insoluble components.
Since these bases do not contain ally fats or oils, they can be easily washed with water from the skin and
clothings. Certain other substances which are used as water soluble bases include tragacanth, gelatin, pectin, silica
gel, sodium alginate, cellulose derivatives, magnesiutn-aluminium silicate and bentonite. In the true sense these
substances are not water soluble but they swell up with the absorption of water.
Surfactants
Surfactants or surface active agents are the substances which when added to a liquid that lower the
surface tension (or interfacial tension) between two liquids or between a liquid and a solid and increase
the solubility.
For e.g. Surfactants decrease the surface tension of a material, coating agent, and a substrate, a tablet. By
reducing the surface tension, the coating can more uniformly cover the tablet surface, resulting in a more
aesthetically pleasing product. When used in suspension, the surfactant facilitates the wetting of the drug particle,
facilitating its ability to go into solution.
They may be used as emulsifying agents, detergents, solubilising agents, wetting agents, foaming agents.
antifoarning agents, flocculating agents and deflocculating agents.

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Properties of surfactants: A surfactant must fulfil two structural requirements-
a) A surfactant must contain a lipophilic region.
b) A surfactant must contain a hydrophilic region.
In a surfactant both hydrophilic and lipophilic region must be balanced because then both the regions
will be concentrated at an interface and therefore surface tension will be lowered.
Types of surfactants
Surfactants can be classified in a number of ways but the most widely acceptable classification system is
based on ionic behaviour in the solutions.
There are of four types of surfactants based on the charge of the hydrophilic region.
1. Anionic surfactant (here the hydrophilic region is negatively charged i.e. an anion): They ionise in
aqueous solutions into a large anion. e.g. Sodium lauryl sulphate - It is used as an excipient on some
dissolvable aspirins and other fibre therapy caplets.
2. Cationic surfactant (here hydrophilic region is positively charged i.e. a cation): They ionise in aqueous
solutions into a large cation. e.g. Cetyl trimethyl ammonium bromide (cetrimide) - is an effective
antiseptic agent against bacteria and fungi.
3. Non-ionic surfactants : They do not ionise in aqueous solution.
e.g. Tween 80 ( polyoxyethylene sorbitol monooleate)- Polysorbate 80 is an excipient that is used to
stabilize aqueous formulations of medications for parenteral administration
Span (sorbitan ester of lauric acid)
4. Amphoteric surfactant: e.g. Lecithin- it acts as a wetting, stabilizing agent and a choline enrichment
carrier, helps in emulsifications and encapsulation, and is a good dispersing agent. N-dodecyl alanine.
Figure: Different types
of micelles.
(A) Spherical micelle of
an anionic surfactant;
(B) spherical micelle of
a nonionic surfactant;
(C) cylindrical micelle of
an ionic surfactant;
(D) lamellar micelle of
an ionic surfactant;
(E) reverse micelle of an
anionic surfactant in
oil.
(From Shinoda K,
Nakagawa T,
Tamamushi B-I,
Isemura T. Colloidal
Surfactants. New
York: Academic Press,
1963.)

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The mechanism action of surfactant
The molecules of a surfactant consist of two parts, i.e. a polar part and non-polar part. When such
molecules are placed in two phases of different polarities the polar part moves towards high polarity
phase while non-polar part moves towards the low polarity phase and preferentially they are absorbed
at the interphase. As the concentration is increased a level is reached where the interphase becomes
saturated with surface active agents and no more space is available at the surface to be occupied.
Therefore the surfactant molecules move towards the bulk of the solution. At this concentration an
unusual phenomenon occurs. The molecules tend to form colloidal aggregates known as micelles
consisting of 50 to 150 molecules of surface active agents. The concentration of surfactant at which the
micelles are formed is known as critical micelle concentration or C.M.C. The solubilization begins at
C.M.C and generally increases with increase the concentration of micelles.
Micelle: The colloidal aggregate molecules consisting of 50 to 150 molecules of surface active agents known as
micelles. C.M.C: The concentration of surfactant at which the micelles are formed is known as critical micelle
concentration or C.M.C.
Emulsifying agents (Emulgents or Emulsifier)
Emulsifying agents are those substances used in the emulsion to reduce the interfacial tension between
the two phases i.e. aqueous phase and oily phase thus make them miscible with each other to form a
stable emulsion.
Classification
Emulsifying agents may be classified as follows:
1. Natural emulsifying agents from vegetable origin
The natural emulsifying agents obtained from vegetable sources are carbohydrates which include gums and
mucilaginous substances. They are anionic in nature and produce O/W emulsion. Examples are
a. Acacia
b. Tragacanth
c. Agar
d. Chondrus (Irish moss0
e. Pectin
f. Starch.
2. Natural emulsifying agents from animal origin
Examples are
a. Gelatin
b. Egg yolk
c. Wool fat (Anhydrous lanolin)
3. Semi-Synthetic polysaccharides
Examples are
a. Methyl Cellulose
b. Sodium carboxymetjhyl cellulose
4. Synthetic emulsifying agents
This group includes surface active agents.Examples are
a. Anionic: Various alkali soaps, metallic soaps, sulphated alcohols and sulphonates.
b. Cationic: Quaternary ammonium compounds.
c. Non-ionic: Glyceryl esters e.g. Glyceryl monostearate.
5. Inorganic emulsifying agents
Examples are
a. Magnesium oxide
b. Magnesium trisilicate
c. Magnesium aluminium silicatwe
d. Bentonite

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6. Alcohols
Examples are
a. Cholesterol
b. Carbowaxes
The choice of emulsifying agents
To get an emulsion of required properties, the emulsifying agent selected must have the following qualities.
1. It should be capable of reducing the interfacial tension between the two immiscible liquids.
2. It should be capable of keeping the globules of dispersed liquid distributed indefinitely throughout the
dispersion medium.
3. It should be non-toxic,
4. The odour and taste should be compatible with the preparation.
5. It should be chemically compatible with other ingredients of the preparation.
6. It should be able to produce and maintain the required consistency of the preparation.
Organoleptic Additives
Organoleptic properties are those which can be sensed with organs. In case of pharmaceutical
preparations ,three of these properties can be changed to make a pharmaceutical product more
palatable and more attractive, especially for liquid dosage forms.
These are i. Color ii. Odor and iii. Taste
Colors
Colouring agents may be defined as the substances used to impart colour to foods, drugs and cosmetics
to increase their organoleptic properties. In the pharmaceutical products Colouring agents impart the
preferred colour to the formulation. The function of these ingredients is to enhance the product quality.
They are used for
1. Product identification.
2. Increasing product acceptability to the patients.
3. Giving warning.
4. Producing standard preparations.
Sources
Colours may be obtained from
1. Mineral: Colours obtained from minerals are also known as pigments. e.g. ferric oxide (yellow
and red), carbon black, titanium di oxide, Prussian blue etc.
2. Plants: Different colours obtained from plants. e.g. Chlorophyll, indigo, alizarin, carotenoids,
flavones etc.
3. Animal: The animal world has been comparatively a minor source of colours. e.g. Tyrian blue,
Cochineal etc.
4. Synthetic: The synthetic colours are prepared from coal tar dyes. e.g. nitro-dyes, nitroso-dyes,
azo-dyes, thiazines etc.
They are either soluble or form fine suspension in the solvent system. For uniform distribution the
particle size must be < 10 microns. If a very light shade is desired a concentration is less than 0.01%.
On the other hand if dark colour is required concentration is more than 2%.
Example: White: Titanium dioxide
Blue : Brilliant blue ,Indigo carmine
Red : Amaranth Carmine
Yellow: saffron
Brown: caramel

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Flavouring agents and perfumes
Flavouring agents are the substances which are used to impart pleasant smell to the preparation and to
mask specific type of taste of the preparation, thus make them more palatable and improve patient
acceptance.
The four basic taste sensations are salty, sweet, bitter and sour. It has been proposed that certain
flavours should be used to mask these specific taste sensations.
Example: Clove oil, citric and syrup, glycerin, rose oil, orange oil, raspberry flavor, vanilla flavor etc.
Classification flavouring agents
1. Natural flavouring agent: The flavouring agents obtained from natural sources include pine-apple,
banana, cardamom, ginger, cinnamom, peppermint and volatile oils obtained from anise, caraway
clove, dill, lemon oil, orange, rose, jasmine, lavender etc. Malt extract, glycyrrhizin extract, coffee,
vanilla, chocolate and tolu balsam are also used as flavouring agents. Menthol, mannitol, chloroform
spirit and chloroform water are widely used as flavouring agents in liquid formulations.
2. Synthetic colouring agent: Synthetic chemical like certain alcohol, aldehydes, esters, fatly acids,
ketones and lactones are used as flavouring agents. More recent butterscotch, „tutti-frutti‟ flavor are
used.
Q. Why synthetic flavouring agents are better than natural flavouring agents.
Most of the flavours used in pharmaceutical preparations are obtained from natural sources but now a day they
are being replaced by synthetic flavours. This is due to,
1. They are constant in composition.
2. They are readily available.
3. They are comparatively cheap.
4. They are more stable.
5. Their incompatibilities are more predictable.
Relation between taste and flavour
There is a close relation between taste and flavour. In case of pharmaceutical p[reparations the
following guidelines should be followed.
Matches between taste and flavours
Taste Flavour/Flavours
Alkaline Mint, Chocolate, vanilla, custard
Acid (Sour) Lemon, orange, raspberry, cherry, strawberry
Bitter Anise, mint, fennel, chocolate, spicy ,cherry
Metallic Grape, lemon, burgundy
Salty Citrus flavour, maple, raspberry, fruity, melon
Sweet Fruity, vanilla, maple, honey
Matches between flavours and colours
Flavours Colures
Cherry, raspberry, strawberry, apple, rose Pink, red
Chocolate, honey, molasses, caramel Brown
Lemon, lime, orange, Cherry Yellow to orange
Banana, mint,, pistachio Green
Vanilla, mint, spearmint, jasmine, banana White to off white
Grape, liquorice Violet to purple
Blue berry, mixed fruit, plum, liquorice blue

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In general, children like very sweet flavours and so do the people in the geriatric group. Children prefer
cherry, grape, orange etc., while the old persons may prefer flavours like orange, cherry, burgundy etc.
Adult preferences are vanilla, strawberry, mint etc. Very strong flavours as a rule should be avoided.
Sweetening agents
Sweetening agents are the substances which are used in the formulations to mask the objectionable
taste of the drug and to make the preparations sweet in taste.
Sweetening agents are usually employed in the liquid formulations designed for oral administration
specifically to increase the palatability of the therapeutic agent.
Example: Sucrose, Lactose, Aspartame, Sorbitol, Mannitol etc.
The main sweetening agents employed in oral preparations are sucrose, liquid glucose, glycerol,
sorbitol, saccharin sodium and aspartame. Aspartame is an artificial sweetening agent. The use of
artificial sweetening agents in formulations is increasing.
The use of sugars in oral formulations for children and patients with diabetes mellitus is to be avoided.
Why mannitol is extensively used in chewable tablets
Chewable tablets are intended to be chewed in the mouth prior to swallowing and are not intended to be
swallowed intact.
The use of sweeteners is primarily limited to the chewable tablets to exclude or limit the use of sugar in the tablet.
Sucrose causes hyperglycaemia. So we have to exclude it in the chewable tablet. Saccharine can use in place of
sucrose, but it has the disadvantage that it has a bitter after taste and has been reported to be carcinogenic.
Aspartame can be used in place of saccharine, but the primary disadvantage of aspartame is its lack of stability
in the presence of moisture.
For the above reason mannitol is used extensively in the chewable tablet because-
a. Mannitol is reportedly about 72% as sweet as sucrose.
b. It does not have bitter after taste.
c. It has the stability in the presence of moisture.
d. It does not produce hyperglycaemia.
Acidifying agents
Acidifying agents are the substances that are used in liquid preparation to provide acidic media for
product stability.
e.g. Citric acid , Acetic acid, Fumaric acid, Hydrochloric acid, Nitric acid .
Air displacement agents
Air displacement agents are the substances employed to displace air in a hermetically sealed container
to enhance product stability. e.g. nitrogen. carbon dioxide.
Alkalizing agents
Alkalinizing agents are the substances which provides alkaline medium for product stability in liquid
preparations. Alklinizing agent excipients are important in pharmaceutical formulations where the active
pharmaceutical ingredient requires an alkaline environment for stability or therapeutic effectiveness.
e.g. Ammonia solution, Ammonium carbonate, Diethanolamine, Monoethanolamine,
Potassium hydroxide, Sodium bicarbonate, Sodium borate, Sodium carbonate, Sodium hydroxide
Trolamine , Sodium citrate/citric acid, Sodium lactate
Alkaline agents are used to balance the acids of our body and to strengthen the effect of cleaning solutions.
Maintaining a proper potential hydrogen (pH) level is vital to our health, keeping cholesterol, blood sugar and the
heart's circular system running smoothly. If pH level is kept at 7, the alkaline and acids are equally balanced,
influencing bone health, proper digestion, electrolyte activity and keeping immunity strong to prevent sickness.

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Anti-Foaming Agent
A defoamer or an anti-foaming agent is a chemical additive that breaks up and inhibits the formation of
foams in liquids by reducing interfacial tension between two phases. In pharmaceutical industry defoamers
are used as to reduce bloating (ফীহত়্া )
A familiar example is the drug Simethicone which is the active ingredient in drugs such as Entacyd plus.
Others include: Dimethicone, Lauric acid NF32, Myristic acid
Palmitic acid.
Properties of an anti-foaming agent
1. It should be insoluble in the foaming medium.
2. It should be surface active.
3. Should have low viscosity.
4. It should spread rapidly on foamy surfaces.
5. It has affinity to the air-liquid surface where it destabilizes the foam lamellas.
Classification
Anti-foaming agents are classified into the following types.
1. Oil based anti-foaming agents: Oil based anti-foaming agents have an oil carrier. Oil and water do
not mix with each other so these are the best anti foaming agents. The oil might be mineral oil,
vegetable oil, white oil or any other oil that is insoluble in the foaming medium except silicone oil.
An oil based defoamer also contains a wax and/or hydrophobic silica to boost the performance. Typical waxes
are ethylene bis stearamide (EBS), paraffin waxes, ester waxes and fatty alcohol waxes. These products might
also have surfactants to improve emulsification and spreading in the foaming medium.
2. Powder anti-foaming agents: Powder anti-foaming agents are in principle oil based defoamers on a
particulate carrier like silica. These are added to powdered products like cement, plaster and detergents.
3. Water based anti-foaming agents: Water based anti-foaming agents are different types of oils and
waxes dispersed in a water base.
The oils are often white oils or vegetable oils and the waxes are long chain fatty alcohol, fatty acid soaps or esters.
These are normally best as deaerator, which means they are best at releasing entrained air.
4. Silicone based anti-foaming agents: Silicone-based anti-foaming agents are polymers with silicon
backbones. These might be delivered as oil or a water based emulsion.
The silicone compound consists of hydrophobic silica dispersed in silicone oil. Emulsifiers are added to ensure
that the silicone spreads fast and well in the foaming medium. The silicone compound might also contain silicone
glycols and other modified silicone fluids.
Buffering agents
A buffering agent adjusts the pH of a solution. These materials, when dissolved in solvent enable the
solution to resist any change in pH. They are added to substances that are to be placed into acidic or
basic conditions in order to stabilize the substance.
Change in the pH of preparation may occur during storage because of degradative reaction in the
product or by the Interaction of the product with container.

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So, buffers are used to maintain a required pH of the formulation in order to:
Ensure physiological compatibility
Maintaining/optimising chemical stability
Maintaining/optimising anti-microbial effectiveness
Optimise solubility (or insolubility if taste is an issue)
Two common types of buffer solutions are:
(1) A weak acid together with a salt of the same acid with a strong base. These are called Acid buffers
e.g., CH3COOH + CH3COONa.
(2) A weak base and its salt with a strong acid. These are called Basic buffers. e.g.
NH4OH + NH4Cl.
The principle buffer systems employed for parenteral preparation are acetate, citrate and phosphate.
Name of buffer System Concentration
Acetate CH3COOH + CH3COONa 1-2%
Citrate Citric acid + Na-citrate 1-3%
Phosphate H3PO4 + H salt 0.8-2%
Carbonate H2CO3 + NaHCO3 1-2%
Mechanism of Action
The way buffering agents work is seen in how buffer solutions work. Using Le Chatelier's principle we get an
equilibrium expression between the acids and conjugate base. As a result we see that there is little change in the
concentrations of the acid and base so therefore the solution is buffered. A buffering agent sets up this
concentration ratio by providing the corresponding conjugate acid or base to stabilize the pH of that which it is
added to. The resulting pH of this combination can be found by using the Henderson-Hasselbalch equation,
which is
Where HA is the weak acid and A is the anion of the base.
The importance‟s of buffer system in pharmaceutical formulation are the following.
Buffered aspirin has a buffering agent, such as MgO, that will maintain the pH of the aspirin as it passes
through the stomach of the patient.
Another use of a buffering agent is in antacid tablets, whose primary purpose is to lower the acidity of the
stomach.
Parenteral solutions for injection into the blood are usually not buffered, or they are buffered to a low capacity so
that the buffers of the blood may readily bring them within the physiologic pH range. If the drugs are to be
injected only in small quantities and at a slow rate, their solutions can be buffered weakly to maintain
approximate neutrality.
Following oral administration, aspirin is absorbed more rapidly in systemic buffered at low buffer capacity then
in systems containing no buffer or in highly buffered preparations. Thus the buffer capacity of the buffer should
be optimized to produce rapid absorption and minimal GI irritation of orally administrated aspirin.
In addition to the adjustment of tonicity and pH for ophthalmic preparations, similar requirements are
demanded for nasal delivery of drugs. Insulin, for example, is more effective by nasal administration than by the
other non-parenteral routs.
The examples of some buffering excipients that are used in pharmaceutical formulation technology are given
below.

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Citric acid: By the concentration of 0.3-.02% improve flavor liquid formulations. 0.3-.02% acts as a suspending
and buffering agents and 0.3-.02% also as an antioxidant.
Sodium Bicarbonate: A concentration of 1.4% Sodium Bicarbonate is used in the preparation of isotonic injection
or infusion solution in pharmaceutical field. Also about 25-50% of Sodium Bicarbonate acts as a source of CO2
in effervescent tablet and granules. Including in some injection (e.g. nicotinic acid) of about 40% of Sodium
Bicarbonate to form more soluble sodium salts.
Sodium Citrate, Dihydrate and Anhydrous: A concentration of about 0.3 –2.0 % of Sodium Citrate used as a
buffering agent in various pharmaceutical formulation like syrup, tablet etc. Also a concentration of 0.3 –2.0 % of
Sodium Citrate may acts as sequestering agents.
Chelating agents
Chelating agents are molecules that are capable of forming complexes with the drug involving more
than one bond it‟s a complex compound contains one or more ring in its structure .
Complexing agents also called “sequestrants” which form chemical complexes with metallic ions.
Sequestrants are used to stabilize fats and oils which undergo rancidity and reversion in the presence of
the metals copper and iron. By chelating (sequestering) metals, oxidation is slow or entirely prevented.
Calcium-Dinatrium-EDTA E385 is the most used one.
e.g., ethylene diamine is bidentate and ethylene diamine tetraacetic acid is hexadentate.
Uses of chelating agent
• EDTA: ethylene diamine tetraacetate is used for the estimation of metals ions.
• EDTAH4: ethylene diamin tetraacetic acid is used for softening water.
• Calcium Disodium Edetate: it is used in the treatment of heavy metal poisoning mostly caused by
lead.
• Disodium Edetate: it is used in hypercalcemic states. It is also useful in the treatment of cardiac
arrhythmias.
Humectants
Humectant is a group of hygroscopic substances used to keep things moist. It is the opposite of a
desiccant. They are used to prevent drying of preparations, particularly ointments and creams.
Glycerin, Propylene glycol, Sorbitol
Function
Their function is to retard evaporation of aqueous vehicle of dosage form-
• To prevent drying of the product after application to the skin
• To prevent drying of product from the container after first opening
• To prevent cap-locking caused by condensation onto neck of container closure of a container after
first opening
N.B: Cap-locking involves liquid products that recrystallized at the bottle-cap interface and makes
opening the bottle difficult after prolonged periods of non-use. These materials are hygroscopic and
should be stored in well closed containers prior to use.
Typical features of humectant
An ideal humectant should have the following criteria-
1. It must absorb moisture from atmosphere and retain the same under the normal conditions of
atmospheric humidity.
2. It should be colourless or not of too intense colour.

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3. It should have good odour and taste.
4. It should be nontoxic and non-irritant.
5. It should be noncorrosive to packaging materials
6. It should not solidify under normal conditions.
7. It should not be too costly.
Classification
There are three types of humectants such as inorganic humectants, metal organic humectants and
organic humectants.
1. Inorganic humectants: These are limited used in cosmetics. Calcium chloride is an example. It has
compatibility problems and corrosive in nature. Hence it is not frequently used in cosmetics.
2. Metal organic humectants: These are limited used in cosmetics because of compatibility problems,
corrosive nature and pronounced taste. The example of this class is sodium lactate.
3. Organic humectants: These are widely used in cosmetics. They include polyhydric alcohols, their
esters and ethers. The most commonly used organic humectants are glycerol, ethylene glycol,
polyethylene glycol (PEG), diethylene glycol, tri ethylene glycol, propylene glycol, dipropylene glycol,
glycerin, sorbitol, mannitol, glucose.
Mode of action
• A humectant attracts and retains the moisture in the nearby air via absorption, drawing the water
vapour into and/or beneath the organism/object's surface.
• By contrast, desiccants also attract ambient moisture, but adsorbs -- not absorbs -- it, by condensing
the water vapour onto the surface, as a layer of film.
• Humectants absorb water vapours from atmosphere till a certain degree of dilution is attained.
Aqueous solutions of humectants can reduce the rate of loss of moisture.
Wetting and/or solubilizing agent
Reduces the surface tension of water, allowing it to spread more easily, and/or improves the solubility
of poorly water soluble drugs. They increase the spreading and penetrating properties of a liquid by
lowering its surface tension.
The surface tension of a liquid is the tendency of the molecules to bond together, and is determined by
the strength of the bonds or attraction between the liquid molecules. A wetting agent stretches theses
bonds and decreases the tendency of molecules to bond together, which allows the liquid to spread
more easily across any solid surface.
Examples
e.g.
• Oral: polysorbates (Tweens), sorbitan esters (Spans)
• Parenteral: polysorbates, poloxamers, lecithin
• External: sodium lauryl sulphate
But these can cause excessive foaming and can lead to deflocculation and undesirable physical instability
(sedimentation) if levels too high.
Hydrophilic colloids that coat hydrophobic particles, e.g. bentonite, tragacanth, alginates, cellulose
derivatives. Also used as suspending agents, these can encourage deflocculation if levels are too low.

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Solvents/Co-Solvents
Solvent: A solvent is a substance that can dissolve a solute (a chemically different liquid, solid or gas)
resulting in solution. A solvent is usually a liquid but it can also be solid or a gas. A solvent never
changes its state forming a solution. Water and hydroalcoholic alcohol, water and glycerin may be used
as co-solvents when needed. Sterile solvents are used in preparations such as injections.
Ideal characteristics of solvent
1. It should either dissolve or disperse the polymer system.
2. It should easily disperse other coating solution component into the solvent system.
3. Small concentration of polymer (2-10%) should not result in an extremely viscous solution system
(>300cps) creating processing problem.
4. It should be colorless, tasteless, odorless, in-expensive, non-toxic, inert and non-flammable.
5. It should have rapid drying rate.
6. It should have no environmental impact.
Classification
On the basis of the forces of interaction occurring in solvents, one may broadly classify solvents as one
of three types:
1. Polar solvents: Those made up of strong dipolar molecules having hydrogen bonding are known as
polar solvent. e.g., water or hydrogen peroxide.
2. Semi-polar solvents: Those also made up of strong dipolar molecules but that do not form hydrogen
bonds are known as semi-polar solvent. e.g., acetone or pentyl alcohol.
3. Non-polar solvents: Those made up of molecules having a small or no dipolar characters are known
as non-polar solvent. e.g., benzene, vegetable oil, or mineral oil.
Normally solvation of a solvent depends upon its classification. Generally polar solvent dissolves polar
compound best and non-polar solvent dissolves non polar compound best.
Examples
• The first choice for a solvent is water in which a drug is freely soluble.
• Water –miscible solvent such as Chlordiazepoxide hydrochloride can be used to improve solubility and
stability.
• Oils are used as emulsion; intramuscular injections and liquid fill oral preparation.
• Aqueous methanol is widely used in HPLC and is the standard solvent in sample extraction.
• Other acceptable non-aqueous solvents are glycerol, propylene glycol, ethanol and are used generally
for a lipophilic drug.
Water is the solvent most widely used as a vehicle due to
constant), but
Likely to cause instability of hydrolytically unstable drugs
Good vehicle for microbial growth

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Co-solvent
Co-solvents are defined as water-miscible organic solvents that are used in liquid drug formulations to
increase the solubility of poorly water soluble substances or to enhance the chemical stability of a drug.
Properties of co-solvent
• Co-solvent increases the solubility of a drug.
• An ideal co-solvent should possess values of dielectric constant between 25 and 80.
• The most widely used system that will cover this range is a water/ethanol blend.
• It should not cause toxicity or irritancy when administrated for oral or parental use
• Other co-solvents are sorbitol, glycerol, propylene glycol and syrup.
Application of co-solvent
Water-miscible co-solvents are used to:
Enhance solubility, taste, anti-microbial effectiveness or stability
Reduce dose volume (e.g. oral, injections) Or, conversely, optimise insolubility (if taste of API is an
issue)
Examples: propylene glycol, glycerol, ethanol, low molecular weight PEGs
Water-immiscible co-solvents, e.g. Emulsions / microemulsions using fractionated coconut oils
Complexing agents
Complexing agents are widely used in various industrial processes and household products throughout
the world. Amongst the well-known complexing agents, not only EDTA but also DTPA (Pentetic acid or
diethylenetriaminepentaacetic acid (DTPA) is an aminopolycarboxylic acid consisting of a
diethylenetriamine backbone with five carboxymethyl groups. The molecule can be viewed as an
expanded version of EDTA and is used similarly. It is a white, water-soluble solid.) and NTA
(Nitrilotriacetic acid (NTA) is the aminopolycarboxylic acid with the formula N(CH2CO2H)3. It is a
colourless solid that is used as a chelating agent, which forms coordination compounds with metal ions
(chelates) such as Ca2+, Cu2+, and Fe3+ ) are widely used.
These substances that forms stable water-soluble complexes (chelates) with metals and are used in some
liquid pharmaceuticals as stabilizers to complex heavy metals that might promote instability. In such use,
they are also called sequestering agents.
Stiffening agents
Stiffening agent excipients are used primarily in topical preparations for increasing the preparation‟s
viscosity or thickness or hardness. Often stiffening agents find application as sustained-release carriers
and to minimize sweating and bleeding of oil-wax blends.
Examples: cetyl alcohol, cetyl esters wax, microcrystalline wax, paraffin, stearyl alcohol, white wax,
yellow wax

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Essentials for real life exam and via board
Antiadherents
Antiadherents reduce the adhesion between the powder (granules) and the punch faces and
thus prevent sticking to tablet punches by offering a non-stick surface. They are also used to
help protect tablets from sticking. The most commonly used is magnesium stearate. Other
includes Talc, Starch, Cellulose
Antiadherent: The function of an antiadherent is to reduce adhesion between the powder and the punch faces and thus
prevent particles sticking to the punches. Many powders are prone to adhere to the punches, a phenomenon (known in the
industry as sticking or picking) which is affected by the moisture content of the powder. Such adherence is especially prone
to happen if the tablet punches are engraved or embossed. Adherence can lead to a build-up of a thin layer of powder on
the punches, which in turn will lead to an uneven and matt tablet surface with unclear engravings. Many lubricants, such as
magnesium stearate, have also antiadherent properties. However, other substances with limited ability to reduce friction can
also act as antiadherents, such as talc and starch.
Glidants
Functions of glidants: Glidants are used to promote powder flow by reducing interparticle
friction and cohesion. These are used in combination with lubricants as they have no ability to
reduce die wall friction.
Examples of Glidants: Silica, Magnesium stearate, Talc, Fumed silica, Colloidal silicon dioxide,
talc, syloid, aerosil and magnesium carbonate.
The role of the glidant is to improve the flowability of the powder. This is especially important during tablet production at
high production speeds and during direct compaction. However, because the requirement for adequate flow is high, a glidant
is often also added to a granulation before tabletting.
Lubricants
Lubricants prevent ingredients from clumping together and from sticking to the tablet punches
or capsule filling machine. Lubricants also ensure that tablet formation and ejection can occur
with low friction between the solid and die wall.
Common minerals like talc or silica, and fats, e.g. vegetable stearin, magnesium stearate or
stearic acid are the most frequently used lubricants in tablets or hard gelatin capsules. Others
include: Magnesium stearate, Stearic acid, Polyethylene glycol, Sodium lauryl sulphate, Sodium stearyl fumarate, Liquid
paraffin
Lubricants are agents added in small quantities to tablet and capsule formulations to improve
certain processing characteristics.
Lubrication is achieved by mainly two mechanisms: Fluid lubrication and boundary lubrication.
Fig. 27.8 Schematic illustration of lubrication mechanisms by fluid and boundary lubrication.

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There are three roles identified with lubricants as follows:
True lubricant role: To decrease friction at the interface between a tablet’s surface and
the die wall during ejection and reduce wear on punches & dies.
Anti-adherent role: Prevent sticking to punch faces or in the case of encapsulation,
lubricants. Prevent sticking to machine dosators, tamping pins, etc.
Glidant role: Enhance product flow by reducing interparticulate friction.
There are two major types of lubricants:
Hydrophilic: Generally poor lubricants, no glidant or anti-adherent properties.
Hydrophobic: Most widely used lubricants in use today are of the hydrophobic category.
Hydrophobic lubricants are generally good lubricants and are usually effective at
relatively low concentrations. Many also have both antiadherent and glidant
properties. For these reasons, hydrophobic lubricants are used much more frequently
than hydrophilic compounds. Examples include magnesium stearate.
Table: Different between glidant and lubricant
Glidant Lubricant
1. A substance that is added to a powder to
improve its flowability.
1. A substance used to reduce friction between
objects or surfaces.
2. The glidant is often added to a
granulation before tableting.
2. Lubricant gives action after tableting.
A Glidant's effect is due correcting surface
irregularity, reducing interparticular
friction & decreasing surface charge.
lubrication is achieved by Thick-Film lubrication
(Fluid-Film or hydrodynamic lubrication) , Thin
Film lubrication (Boundary lubrication) and
Extreme Pressure lubrication
4. They reduce the interparticulate friction. 4. Reduce friction between solid and die cavity.
5. Usually glidant are solid. 5. Lubricant may be liquid.
6. e.g. Silica, Magnesium carbonate, talc,
syloid, aerosil etc.
6. e.g. Stearic acid, Magnesium stearate, Calcium
stearate, polyethylene glycol etc.
Binders
Binders hold the ingredients in a tablet together. Binders ensure that tablets and granules can
be formed by increasing cohesive state of the drug powder, with required mechanical strength.
In other word according to WHO binders act as an adhesive to ‘bind together’ powders,
granules and tablets to result in the necessary mechanical strength.
Binders can be added to a powder in different ways:
As a dry powder which is mixed with the other ingredients before wet agglomeration.
During the agglomeration procedure the binder might thus dissolve partly or completely
in the agglomeration liquid;
As a solution which is used as agglomeration liquid during wet agglomeration. The
binder is here often referred to as a solution binder.

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As a dry powder which is mixed with the other ingredients before compaction
(slugging or tabletting). The binder is here often referred to as a dry binder.
As a dry powder with other excipients in dry granulation (roller compaction, slugging)
or as an extra-granular excipient in a wet granulation tablet formulation.
As a dry powder with other intra-granular excipients in wet granulation. When the
granulating fluid is added, the binder may dissolve partially or completely to then
exhibit adhesive binding properties in helping granules to form.
Most commonly in wet granulation, the binder is added already dissolved in the
granulating fluid to enable a more effective and controllable granule formation.
Important examples of dry binders.
 Saccharides and their derivatives:
o Disaccharides: sucrose, lactose;
o Polysaccharides and their derivatives: starches, cellulose or modified cellulose
such as microcrystalline cellulose and cellulose ethers such as hydroxypropyl
cellulose (HPC);
o Sugar alcohols such as xylitol, sorbitol or maltitol;
 Protein: gelatin;
 Synthetic polymers: polyvinylpyrrolidone (PVP), polyethylene glycol (PEG).
Typical features of binders:
A binder should
Be compatible with other products of formulation and
Add sufficient cohesion to the powders.
Classification and examples: Binders are classified according to their application,
Dry binders are added to the powder blend, either after a wet granulation step, or as
part of a direct powder compression (DC) formula. e.g., Pregelatinised starch, cross-
linked PVP, cellulose, methyl cellulose, and polyethylene glycol.
Solution binders are dissolved in a solvent (for example water or alcohol can be used in
wet granulation processes). e.g., PVP, HPMC, gelatin, cellulose, cellulose derivatives,
starch, sucrose and polyethylene glycol.
Soluble in water/ethanol mix: PVP
Acacia, Tragacanth, Gelatin, Sucrose, Starch paste are soluble in water and are not used in
water sensitive drugs, while Na-alginate, Methyl cellulose dissolved in alcohol and PVP, Methyl
cellulose drugs, while Na-alginate, Hydroxy Propyl cellulose dissolved both water and alcohol.
In case of water sensitive drugs first bender need to dissolve on alcohol and then other
excipients and active ingredients are mixed with it.

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Other example of binders include Alginic Acid, Sodium alginate, Carboxymethyl cellulose
sodium (CMC), Microcrystalline cellulose (MCC), Powdered cellulose, Confectioner’s sugar,
Dextrin, Dextrose, Ethylcellulose, Guar gum, Hydroxypropyl cellulose (HPC), Hypromellose
(HPMC), Lactose, Maltodextrin, Methylcellulose, Povidone, Zein.
Table: Some binders their concentration and required solvent are given below.
Binders Used concentration Required solvent
1. Acacia 2-5% H2O
2. Tragacanth 1-3% H2O
3. Sucrose 2-20% H2O
4. Gelatin 1-4% H2O
5. Starch past 1-4% H2O
6. Na-alginate 3-5% Alcohol
7. Methyl cellulose 1-4% Alcohol
8. Pyrrolidone 2-5% H2O and Alcohol
9. Ethyl celluese 0.2-0.5% H2O and Alcohol
Diluents/ Fillers
When the quantity of a drug for an individual dose is very small then it is practically impossible
to compress then the inert substances which are added to increase the bulk for easy
compression a known as filler or the diluent.
Diluent’s are filler used to make required bulk of tablet when the dosage itself is inadequate to produce this bulk.
Secondary reason is to provide better tablet properties such improved cohesion, to permit use of direct
compression manufacturing, or to promote flow.
Fillers typically also fill out the size of a tablet or capsule, making it practical to produce and
convenient for the consumer to use. e.g., Minimum tablet weight is typically ~50mg. Actual API
doses can be as low as ~20μg, e.g. for oral steroids.
In order to form tablets of a size suitable for handling, a lower limit in terms of powder volume and weight is
required. Tablets weigh normally at least 50 mg. Therefore, a low dose of drug per tablet requires the
incorporation of a substance into the formulation to increase the bulk volume of the powder and hence the size of
the tablet. This excipient, known as the filler or the diluent, is not necessary if the dose of the drug per tablet is
high.
Function of fillers
Bulking agent: Fillers add volume and/or mass to a drug substance, thereby facilitating
precise metering and handling thereof in the preparation of dosage forms . Used in
tablets and capsules.
Compression aid: Deforms and/or fragments readily to facilitate robust bonding in tablet
compacts, e.g. microcrystalline cellulose.
Good bulk powder flow diluents have a strong influence: Good flow of bulk powders is
very important in designing a robust commercial tablet product.

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Typical features of fillers: An ideal diluent should have the following criteria-
1. They should typically be inert and non-toxic.
2. They should have an acceptable taste.
3. They must be compatible with the other components of the formulation.
4. They must be physically and chemically stable.
5. They must be non-hygroscopic.
6. They must be free from any unacceptable microbiologic load.
7. They must be commercially available is all acceptable grade.
8. They do not alter bioavailability of the drug.
9. They must be colour compatible.
10. They should be biocompatible
11. They should possess good biopharmaceutical properties (e.g. water soluble or hydrophilic)
12. They should possess good technical properties (such as compactability and dilution
capacity)
13. They should be cheap.
Examples: Plant cellulose and dibasic calcium phosphate are used popularly as fillers. A range
of vegetable fats and oils can be used in soft gelatin capsules. Other examples of fillers
include: lactose, sucrose, glucose, mannitol, sorbitol, calcium carbonate, calcium sulfate,
magnesium stearate, Microcrystalline cellulose (MCC), Powdered cellulose, Dextrates, Dextrin,
Dextrose, Kaolin, Maltodextrin, Starch, Sucrose
Lactose, Sucrose, Glucose, Mannitol, Sorbitol, Calcium phosphate, Calcium carbonate, Cellulose
Favoured combinations: Lactose is an excellent choice of filler in many respects but can exhibit
poor flow characteristics, so is often combined with free-flowing microcrystalline cellulose in
wet granulation formulations.
Disintegrants
Disintegrants are substances or mixture of substances added to the drug formulations, which
facilitate dispersion or breakup (disintegration) of tablets and contents of capsules into smaller
particles for quick dissolution when it comes in contact with water in the GIT.
They are mainly two types-
a. Substances which hydrate and swell up in contact with water.
b. Substances which react with effervescent when they come in contact with moisture for
example combination of Na-CO3, citric acid and tartaric acid.
Ideal properties of disintigrants
Good hydration capacity, poor solubility, poor gel formation capacity.
Mode of action: The disintegration process for a tablet occurs in two steps. First, the liquid wets
the solid and secondly penetrates the pores of the tablet. Thereafter, the tablet breaks into
smaller fragments.
Disintegrants that facilitate water uptake: These disintegrants act by facilitating the transport of
liquids into the pores of the tablet, with the consequence that the tablet may break into
fragments. One obvious type of substance that can promote liquid penetration is surface active
agents.
Disintegrants that will rupture the tablet: Rupturing of tablets can be caused by swelling of the
disintegrant particles during sorption of water.

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• In many cases water uptake alone will cause disintegration, by rupturing the intra-particle
cohesive forces that hold the tablet together and resulting in subsequent disintegration.
• If swelling occurs simultaneously with water uptake, the channels for penetration are
widened by physical rupture and the penetration rate of water into the dosage form increased.
• Evaluation of CO2 on effervescent tablet is one of the ways of disintegration.
And a third group of disintegrant functions by producing gas, normally carbon dioxide, in
contact with water. Such disintegrants are used in effervescent tablets and normally not in
tablets that should be swallowed as a solid.
Examples: The most traditionally used disintegrant in conventional tablets is starch, among
which potato, maize and corn starches are the most common types used.
PVP, CMC, Sodium starch glycolate, Alginic Acid, Sodium alginate, Microcrystalline cellulose
(MCC), Croscarmellose sodium, Crospovidone, Guar gum, Polyacrilin Potassium, Sodium Starch
Glycolate, Veegum HV, bentonite 10% and cellulose derivatives Ac-Di-Sol(Na-CMC), Alginate.
Q. Why are disintegrates added in two fractions for the formulation of tablet dosage form?
During manufacturing the tablets disintegrating agents are added in two steps-
a. Major part is incorporated to the powder before granulation.
b. Other part is mixed with the dried granulation along with lubricants before compression.
Disintegrates are added in a manner to serve two purposes-
a. The disintegrates added after granulation breaks the tablet apart into granules
b. The portion added before granulation convert granules into fine particles thus facilitating
tablet dissolution.
The disintegrating time depend on-
1. Quality of diluent, binder, lubricant
2. Hardness of tablet
3. Size of granules
4. And finally on coating.
Super disintegrates: These disintegrates which swells up to 10 to fold within 30 seconds when
they water. Significant improvement in disintegrant performance was achieved with the
introduction of the first super disintegrant.
For example-
Cross carmellose-cross linked cellulose
crosslinked sodium carboxymethyl cellulose (croscarmellose
sodium).
crosslinked polyvinylpyrrolidone (crospovidone
Sodium starch glycolate-cross linked starch.

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List of Superdisintegrants
Superdisintegrants Example of Mechanism of action Special comment
Crosscarmellose(r)
Ac-Di-Sol(r)
Nymce ZSX(r)
Primellose(r)
Solutab(r)
Vivasol(r)
Crosslinked
cellulose
-Swells 4-8 folds in <
10 seconds.
-Swelling and wicking
both.
-Swells in two
dimensions.
-Direct compression
or granulation
-Starch free
Crosspovidone
Crosspovidon M(r)
Kollidon(r)
Polyplasdone(r)
Crosslinked PVP
-Swells very little and
returns to original
size after
compression but act
by capillary action
-Water insoluble and
spongy in nature so
get porous tablet
Sodium starch glycolate
Explotab(r)
Primogel(r)
Crosslinked starch
-Swells 7-12 folds in
<30 seconds
-Swells in three
dimensions and high
level serve as sustain
release matrix
Alginic acid NF
Satialgine(r)
Crosslinked alginic
acid
-Rapid swelling in
aqueous medium or
wicking action
-Promote
disintegration in
both dry or wet
granulation
Soy polysaccharides
Emcosoy(r)
Natural super
disintegrant
-Does not contain
any starch or sugar.
Used in nutritional
products.
Calcium silicate -Wicking action
-Highly porous,
-light weight
-optimum
concentration is
between 20-40%
Granulating Agents
Granulating agents are the substances which are added to powders during granulating process
to convert fine powders into granules. Insufficient quantity of granulating agent may lead to
poor adhesion, soft tablets and capping, where as excessive quantity may lead to hard tablets
into grater disintegration time.
Example: Commonly used granulating agents are water, mucillages of acacia, tragacanth,
Copolyvidone, sucrose and starch. Liquid glucose syrup and alcohol in various dilutions.
Alcohols are used for water sensitive drug.

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EXAMPLES OF PHARMACEUTICAL INGREDIENTS
Ingredient type Definition Examples
Acidifying agent Used in liquid preparations to provide acidic medium for
product stability
Citric acid
Acetic acid
Fumaric acid
Hydrochloric acid
Nitric acid
Alkalinizing agent Used in liquid preparations to provide alkaline medium for
product stability
Ammonia solution
Ammonium carbonate
Diethanolamine
Monoethanolamine
Potassium hydroxide
Sodium bicarbonate
Sodium borate
Sodium carbonate
Sodium hydroxide
Trolamine
Adsorbent An agent capable of holding other molecules onto its surface by
physical or chemical (chemisorption) means
Powdered cellulose
Activated charcoal
Aerosol propellant Agent responsible for developing the pressure within an aerosol
container and expelling the product when the valve is opened
Carbon dioxide
Dichlorodifl uoromethane
Dichlorotetrafl uoroethane
Trichloromonofl
uoromethane
Air displacement Agent employed to displace air in a hermetically sealed
container to enhance product stability
Nitrogen
Carbon dioxide
Antifungal preservative Used in liquid and semisolid preparations to prevent growth of
fungi. Effectiveness of parabens is usually enhanced by use in
combination
Butylparaben
Ethylparaben
Methylparaben
Benzoic acid
Propylparaben
Sodium benzoate
Sodium propionate
Antimicrobial
preservative
Used in liquid and semisolid preparations to prevent
growth of microorganisms
Benzalkonium chloride
Antioxidant Used to prevent deterioration of preparations by
oxidation
Ascorbic acid
Ascorbyl palmitate
Butylated hydroxyanisole
Butylated hydroxytoluene
Hypophosphorous acid
Monothioglycerol
Propyl gallate
Sodium ascorbate
Sodium bisulfi te
Sodium formaldehyde
Sulfoxylate
Sodium metabisulfi te
Buffering agent Used to resist change in pH upon dilution or addition of acid or
alkali
Potassium metaphosphate
Potassium phosphate,
monobasic
Sodium acetate
Sodium citrate, anhydrous
and dihydrate
Chelating agent Substance that forms stable water-soluble complexes (chelates)
with metals; used in some liquid pharmaceuticals as stabilizers
to complex heavy metals that might promote instability. In such
Edetic acid
Edetate disodium

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use, they are also called sequestering agents
Colorant Used to impart colour to liquid and solid
(e.g., tablets and capsules) preparations
FD&C Red No. 3
FD&C Red No. 20
FD&C Yellow No. 6
FD&C Blue No. 2
D&C Green No. 5
D&C Orange No. 5
D&C Red No. 8
Caramel, Ferric oxide, red
Clarifying agent Used as a filtering aid for its adsorbent qualities Bentonite
Emulsifying agent Used to promote and maintain dispersion of finely subdivided
particles of liquid in a vehicle in which it is immiscible. End
product may be a liquid emulsion or semisolid emulsion (e.g., a
cream)
Acacia
Cetomacrogol
Cetyl alcohol
Glyceryl monostearate
Sorbitan monooleate
Polyoxyethylene 50 stearate
Encapsulating agent Used to form thin shells to enclose a drug for ease of
administration
Gelatin
Flavorant Used to impart a pleasant flavour and often odour to a
preparation. In addition to the natural flavorants listed, many
synthetic ones are used
Anise oil
Cinnamon oil
Cocoa
Menthol
Orange oil
Peppermint oil
Vanillin
Humectant Used to prevent drying of preparations, particularly ointments
and creams
Glycerin
Propylene glycol
Sorbitol
Levigating agent Liquid used as an intervening agent to reduce the particle size
of a powder by grinding, usually in a mortar
Mineral oil
Glycerin
Propylene glycol
Ointment base Semisolid vehicle for medicated ointments Lanolin
Hydrophilic ointment
Polyethylene glycol
ointment
Petrolatum
Hydrophilic petrolatum
White ointment
Yellow ointment
Rose water ointment
Plasticizer Component of fi lm-coating solutions to make fi lm more
pliable, enhance spread of coat over tablets, beads, and
granules
Diethyl phthalate
Glycerin
Solvent Used to dissolve another substance in preparation of a solution;
may be aqueous or not (e.g., oleaginous). Co-solvents, such as
water and alcohol (hydroalcoholic) and water and glycerin, may
be used when needed. Sterile solvents are used in certain
preparations (e.g., injections)
Alcohol
Corn oil
Cottonseed oil
Glycerin
Isopropyl alcohol
Mineral oil
Oleic acid
Peanut oil
Purified water
Water for injection
Sterile water for injection
Sterile water for irrigation
Stiffening agent Used to increase thickness or hardness of a preparation, usually
an ointment
Cetyl alcohol
Cetyl esters wax

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Microcrystalline wax
Paraffi n
Stearyl alcohol
White wax
Yellow wax
Suppository base Vehicle for suppositories Cocoa butter
Polyethylene glycols
(mixtures)
PEG 3350
Surfactant (surface
active agent)
Substances that absorb to surfaces or interfaces to
reduce surface or interfacial tension. May be used
as wetting agents, detergents, or emulsifying agents
Benzalkonium chloride
Nonoxynol 10
Octoxynol 9
Polysorbate 80
Sodium lauryl sulfate
Sorbitan monopalmitate
Suspending agent Viscosity-increasing agent used to reduce sedimentation rate of
particles in a vehicle in which they are not soluble; suspension
may be formulated for oral, parenteral, ophthalmic, topical, or
other route
Bentonite
Carbomer (e.g., Carbopol)
Carboxymethylcellulose
sodium
Hydroxyethyl cellulose
Hydroxypropyl cellulose
Hydroxypropyl
methylcellulose
Kaolin
Methylcellulose
Tragacanth
Veegum
Sweetening agent Used to impart sweetness to a preparation Aspartame
Dextrose
Glycerin
Mannitol
Saccharin sodium
Sorbitol
Sucrose
Tablet antiadherents Prevent tablet ingredients from sticking to punches
and dies during production
Magnesium stearate
Tablet binders Substances used to cause adhesion of powder
particles in tablet granulations
Acacia
Alginic acid
sodium
Compressible sugar (e.g.,
Nu-Tab)
Ethylcellulose
Gelatin
Liquid glucose
Methylcellulose
Povidone
Pregelatinized starch
Tablet and capsule
diluent
Inert filler to create desired bulk, flow properties,
and compression characteristics of tablets and
capsules
Dibasic calcium phosphate
Kaolin
Lactose
Mannitol
Microcrystalline cellulose
Powdered cellulose
Precipitated calcium
carbonate
Sorbitol
Starch
Tablet coating agent Used to coat a tablet to protect against decomposition by
atmospheric oxygen or humidity, to provide a desired release
pattern, to mask taste or odour, or for aesthetic purposes.

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Coating may be sugar, fi lm, or thick covering around a tablet.
Sugar-coated tablets generally start to break up in the stomach.
Film forms a thin cover around a formed tablet or bead. Unless
it is enteric, film dissolves in the stomach. Enteric coating
passes through the stomach to break up in the intestines. Some
water-insoluble coatings (e.g., ethylcellulose) are used to slow
the release of drug in the gastrointestinal tract
Sugar coating Liquid glucose
Sucrose
Film coating Hydroxyethyl cellulose
Hydroxypropyl cellulose
Hydroxypropyl
methylcellulose
Methylcellulose
(e.g., Methocel)
Ethylcellulose (e.g., Ethocel)
Enteric coating Cellulose acetate phthalate
Shellac (35% in alcohol,
pharmaceutical glaze)
Tablet direct compression
excipient
Used in direct compression tablet formulations Dibasic calcium phosphate
(e.g., Ditab)
Tablet disintegrant Used in solid forms to promote disruption of the mass into
smaller particles more readily dispersed or dissolved
Alginic acid
Polacrilin potassium
(e.g., Amberlite)
Sodium alginate
Sodium starch glycolate
Starch
Tablet glidant Used in tablet and capsule formulations to improve flow
properties of the powder mixture
Colloidal silica
Cornstarch
Talc
Tablet lubricant Used in tablet formulations to reduce friction during tablet
compression
Calcium stearate
Magnesium stearate
Mineral oil
Stearic acid
Zinc stearate
Tablet or capsule
opaquant
Used to render a coating opaque. May be used alone or with a
colorant
Titanium dioxide
Tablet polishing agent Used to impart an attractive sheen to coated tablets Carnauba wax
White wax
Tonicity agent Used to render solution similar in osmotic-dextrose
characteristics to physiologic fluids, e.g., in ophthalmic,
parenteral, and irrigation fluids
Sodium chloride
Vehicle Carrying agent used in formulating a variety of liquids for oral
and parenteral administration. Generally, oral liquids are
aqueous (e.g., syrups) orhydroalcoholic (e.g., elixirs). Solutions
for intravenous use are aqueous, whereas intramuscular
injections may be aqueous or oleaginous
Flavored, sweetened Acacia syrup
Aromatic syrup
Aromatic elixir
Cherry syrup
Cocoa syrup
Orange syrup
Syrup
Oleaginous Corn oil
Mineral oil
Peanut oil
Sesame oil
Sterile Bacteriostatic sodium

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chloride injection
Viscosity-increasing agent Used to render preparations more resistant to
flow. Used in suspensions to deter sedimentation,
in ophthalmic solutions to enhance contact
time (e.g., methylcellulose), to thicken topical
creams, etc.
Alginic acid
Bentonite
Carbomer
Sodium
Methylcellulose
Povidone
Sodium alginate
Tragacanth
REFERENCES
A.K. Gupta, S.S Bajaj:Introduction to pharmaceutics-II; CBS Puplishers and distributors ,New Delhi India, 2009
Chapter Six .
Loyd V. Allen, Jr., PhD; Nicholas G. Popovich, PhD; Howard C. Ansel, PhD : Ansel‟s Pharmaceutical Dosage
Forms and Drug Delivery Systems; Lippincott Williams & Wilkins, Philadelphia 2011 Chapter four 128-132
M.E. Aulton: Pharmaceutics -The science of Dosage form Design, Churchill Living Stone, Second Edition
Remington :Essentials of Pharmaceutics; First edition; Pharmaceutical Press; 1 Lambeth High Street, London
SE1 7JN, UK; 2013, Chapter 36
Raymond C Rowe,Paul J Sheskey,Marian E Quinn : Handbook of Pharmaceutical Excipients, Sixth edition;
Pharmaceutical Press; 1 Lambeth High Street, London SE1 7JN, UK; 2009

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