Notes made by PU student: INTRODUCTION TO DRUG AND DIFFERENT DOSAGE FORMS Drug Pharmaceutical Preparations Manufactured by Pharmaceutical Industry Pharmaceutical Preparations Compounded Individually SOLID DOSAGE FORMS LIQUID DOSAGE FORMS SEMI-SOLID DOSAGE FORM NEW DRUG DELIVERY SYSTEMS

1. Pharmaceutics – II (Dosage Form Science):
INTRODUCTION TO DRUG AND
DIFFERENT DOSAGE FORMS
Drug:
• Drug may be defined as an agent or substance, intended for use in the diagnosis,
mitigation, treatment, cure or prevention of disease in human beings or animals.
• Drugs are rarely administered in their original or crude forms. They are administered
in different dosage forms by converting them into suitable formulations.
• International non-proprietary names (INN, “generic” names)
Direct clinical use of the active drug substances as they are is rare due to the number
of good reasons:
• API handling can be difficult or impossible (e.g., low mg and g doses)
• Accurate drug dosing can be difficult or impossible
• API administration can be impractical, unfeasible or not according to the therapeutical
aims
• Some API can benefit from reducing the exposure to the environmental factors (light,
moisture…), or they need to be chemically stabilised due to the inherent chemical
instability
• API can be degraded at the site of administration (e.g., low pH in stomach)
• API may cause local irritations or injury when they are present at high concentrations
at the site of administration
• API can have unpleasant organoleptic qualities (taste, smell – compliance!)
• Administration of active substance would mean to have no chance for modification
(improvement) of its PK profile
(Crude Drugs)

2. Besides the choice of the active drug substance, you need to also make a responsible
decision regarding the route of administration and the DOSAGE FORM (drug delivery
system) – wrong choice can cause failure of therapy. You should also be able to handle and
administer the drug properly or advise the patient about it – wrong use can cause failure of
therapy.
From Drug Substance to Pharmaceutical Preparation:
• Active drug substance (active pharmaceutical ingredient - API)
• Excipients (inactive pharmaceutical ingredients)
o Technological, biopharmaceutical and/or stability reasons
o Diluents/fillers, binders, lubricants, disintegrants, coatings, preservatives and
stabilizers, colorants and flavourings
o Should always be stated in SPC (important in the case of allergies)
• Pharmaceutical dosage form:
o Determines the physical form of the final pharmaceutical preparation
o Is a drug delivery system which is formed by technological processing (drug
formulation)
o Must reflect therapeutic intentions, route of administrations, dosing etc.
• Pharmaceutical Preparation (PP)
o Particular pharmaceutical product containing active and inactive pharmaceutical
ingredients formulated into the particular dosage form.
o Packed and labelled appropriately
o Two major types of PP according the origin:
▪ Mmanufactured in large scales by pharmaceutical industry (original and
generic preparations)
▪ Compounded individually in compounding pharmacies
Pharmaceutical Preparations Manufactured by Pharmaceutical
Industry:
• Currently the most frequent and favourable approach
• MUST be approved by national authority (FDA);
• Rigorous quality control (QC) and quality assurance (QA) during manufacturing –
with surveillance of national authorities to ensure the safety and effectiveness
• Original pharmaceutical preparations
o undergo full and very extensive pharmacological/toxicological and
pharmaceutical pre-clinical and clinical development and evaluation
o particularly important is the proof of effectiveness and safety
• Generic pharmaceutical preparations (“authorised copies of original
preparations”)
o Can be released after the expiration of the patent protection of the original
preparation

3. o The approval for clinical use is easier due to the prior experience with the
original preparation
o Must be pharmaceutically equivalent: same API, dose, pharmaceutical dosage
form and the same route of administration as in original preparation
o Must be clinically bioequivalent: i.e. it must be of very close PK profile as
original preparation. PK parameters (Cmax, tmax, AUC) are within 80-125 %
range as compared with the original preparation.
o The proof of therapeutic equivalence (comparing directly the clinical
effectiveness) is not commonly required (due to the technical, financial and
ethical issues). Hence, it can be only assumed from the bioequivalence
o Decrease the costs of pharmacotherapy and thus make the drugs more available
Pharmaceutical Preparations Compounded Individually:
• These PP are compounded individually for a particular patient according to the
physician's prescription in a pharmacy licensed for compounding
• In contrast to the past, they are used rather rarely and mostly in specific situations
• Commercially available PP should be preferred over the compounding
• The main advantage of compounded PP is the opportunity to individualize the
pharmacotherapy:
o Hence, the individually compounded PP can be a justified choice when:
▪ The drug in a particular dosage form is not commercially available on the
market
▪ The extraordinary low or high dose is needed (young children, elderly people,
special situations – e.g., intoxications). In this case right dosage strength need
not be readily commercially available for every patient
▪ The patient suffers from the allergy on a specific excipients (e.g., lactose – a
filler, some colorizing/flavouring or antimicrobial agents - parabens) or
another drug appearing in the PP
▪ Patient is unable to use a PP in its commercially available dosage form (e.g.,
children, elderly)
• The major disadvantage is the lack of standardization (it is always a “single-patient
batch”), unavailability of rigorous QC testing and the appropriate clinical evaluation.
Dosage Forms:
• Dosage forms are the carrier through which drug molecules are delivered to sites of
action within the body.
• Every dosage form is a combination of the drug and different kinds of non – drug
components called as Excipients or additives.
• The additives are used to give a particular shape to the formulation, to increase
stability, palatability & more elegance to preparations.

4. Need for Dosage Forms:
• Accurate dose
• Protection e.g. coated tablets, sealed ampoules
• Protection from gastric juice, e.g. enteric coated tablets
• Masking unpleasant taste and odour
• Provide drugs within body tissues, e.g. injection
• Sustained release medication
• Facilitation of Insertion of drugs into body
• Provide optimum drug action through inhalation therapy
• Provide drug action through topical administration at local area of body e.g. creams
ointment, emulsion, lotions etc
• Use of desired vehicle for insoluble drugs
Classification:
SOLID DOSAGE FORMS:

5. • Solid dosage forms one of the oldest dosage forms and most of the solid dosage forms
are available in Unit dose.
• Unit dose may be defined as a exact quantity of the drug administered at once. e.g.
Tablets, Capsule, pills, cachets, powders etc.
• When drugs are to be administered orally in dry state, then tablets, capsules are most
convenient dosage forms.
• Some solids are supplied in bulk (Means quantity available in large). Bulk powders
can be supplied as Internal (Granules, Fine powders) as well as External (Dusting
Powders, Insufflations etc)
Dusting Powders:
• Dusting powders are applied externally to skin, so they should be applied in very fine
state to avoid local irritation. Hence dusting powders should be passed through sieve
no 80 to obtained fined powders.
• Dusting powders are prepared by mixing of more than one ingredient in which starch,
kaolin, or talc are used in their formulation. Generally talc or kaolin is used because
they are inert in nature.
• Dusting powders are used for antiseptic, astringent, absorbent, antiperspirant etc.
• Dusting powders are of two sub type they are as:
o Medical dusting powder
▪ Medical Dusting powders are used to increase superficial condition of skin.
▪ These are not applied on wounds, burns etc
▪ Medical dusting powders must be free from dangerous pathogenic micro-
organism.
o Surgical Dusting powders
▪ Surgical dusting powders are used in body cavities and also on major wounds
like as burns etc.
▪ They should be sterilized before use.
▪ They are mainly used for their antiseptic, absorbent action.

6. Insufflations:
• These are medicated dusting powders meant for introduction into body cavities (nose,
throat, ear, vagina etc) with the help of an apparatus known as an insufflator.
• It sprays the powders (in a state of fine particles) on site of application.
• Now a day’s insufflations are also available in pressure aerosols. These pressure
aerosols are used for administration of potent drug.
• They are used in the treatment of ear, nose, and throat infections with antibiotics to
produce local effect of drugs.
Snuffs:
• These are finely divided solid dosage forms of medicaments which are inhaled into
nostrils.
• They are mainly used for their antiseptic, bronchodilator and decongestion action.
Granules:
• Granulation is the process in which primary powder particles are made to adhere to
form larger multi-particle or large particles entities called granules.
• The bitter, nauseous, unpleasant powders cannot be given tablets, capsule due to bulk
quantity are required to be taken, as well as they are not given in liquid dosage forms
due to their stability such powders are given in the granules forms.
• These powders are mixed with suitable excipient along with granulating agent,
prepare a coherent mass then dried & passed through the sieve to obtained desired
size of granules.
• E.g. Effervescent granules
Effervescent Granules:
• Effervescent granules are meant for internal use.
• They contained medicaments mixed with citric acid, tartaric acid & sodium bi
carbonates, sometime saccharin or sucrose may be added for sweetening taste.
• Before, administration desired quantities of granules are dissolved in water, the acid
& bicarbonate reacts with each other to produce effervescence.
• Effervescent granules are prepared by two methods, namely as:
o Heat method
o Wet method
Heat Method:
• A large porcelain or stainless steel evaporating dish is placed over the boiling water
bath.

7. • The dish must be sufficiently hot (generally heating takes place for 1 – 5 min.) before
transferring the powders into it, to ensure rapid liberation of water of crystallization
from citric acid.
• If heating of the dish is delayed then the powder which is added to it, will heat up
slowly & liberated water of crystallization will also be liberated simultaneously.
• As a result, sufficient water will not be available to make a coherent mass.
• This coherent mass will pass through the sieve to obtained suitable size of granules,
dry it in oven at 600
c then packed in air tight container.
Wet Method:
• In this method, all the ingredients are mixed thoroughly
• This powders mixture make moistened with non – aqueous vehicle (e.g. alcohol), to
prepare a coherent mass which is then passed through sieve no 8 to obtained suitable
granules.
• Then dried in oven at 600
C. The dried granules are again passed through the sieve to
break the lumps which may be formed during drying.
• The dried granules are packed in air tight container.
Tablets:
• These are solid dosage forms of medicaments which are prepared by moulding or by
compression with or without Excipients.
• The tablets can be prepared by two methods namely as a dry granulation and Wet
Granulation method.
Capsule:
• Capsules are solid unit dosage forms in which one or more medicaments enclosed
within a shell.
• Capsules mainly divided in to two parts namely as
o Body (Longest part of capsule shell)
o Cap (Smallest part of capsule shell)
• The capsules are generally prepared by gelatin.
• Depending on their formulation, two types of gelatin are used namely as – I) Hard
gelatin, II) Soft gelatin.
Pills:
• These are small, rounded solid dosage forms containing medicaments intended for
oral use.
• The medicaments are mixed with excipients to forms a firms plastic mass.
• The mass is rolled to uniform pill pipe, which cut into numbers of uniform pills. The
pills are spherical in shape & produced by rolling them under wooden pill rounder.

8. • Sometimes pills are coated with varnish, gold leaf, etc to improve finish, unpleasant
taste & stability.
• Now a day’s pills are outdated preparations because of number of disadvantages such
as:
o Disintegration time of pill is uncertain means freshly prepared pills are
disintegrates readily rather than old dried pills.
o It is difficult to prepare pills of uniform size & weight.
LIQUID DOSAGE FORMS:
• It may be defined as “A solution is a liquid-preparation that contains one or more
soluble chemical substances dissolved in a specified solvent”
• Liquid dosage forms are intended for External, Internal or parenteral use.
• The component of the solution which is present in a large quantity is known as
“SOLVENT” where as the component present in small quantity is termed as
“SOLUTE”.
• They mainly classified in to two category namely as:
o Monophasic Liquid dosage forms
o Biphasic liquid dosage forms.
Advantages:
• Immediately available for absorption.
• Administration convenient, particularly for infants, psychotic patients.
• Easy to color, flavor & sweeten.
• Liquids are easier to swallow than solids and are therefore particularly acceptable for
pediatric patient.
• A solution is a homogeneous system and therefore the drug will be uniformly
distributed throughout the preparation.
• Some drugs like aspirin, KCl can irritate gastric mucosa if used orally as a solid
dosage forms. But this effect can be reducing by solution system.

9. Disadvantages:
• Less stable in aqueous system. Incompatibility is faster in solution than solid dosage
form.
• Patients have no accurate measuring device.
• Accident breakage of container results in complete loss.
• Solutions often provide suitable media for the growth of micro organisms.
• The taste of a drug, which is often unpleasant, is always more pronounced when in
solution than in a solid form.
• Bulky than tablets or capsule, so difficult to carry transport.
Monophasic Liquid Dosage Forms:
• Monophasic liquid dosage forms are represent by true or colloidal solution.
• A solution is homogenous because the solute is an ionic or molecular form of
subdivision.
• In case of colloidal solutions, the solutes are present as aggregates although they
cannot be seen by necked eye or ordinary microscope.
• It is sub classified in Monophasic liquid dosage forms for internal or external use.

10. Monophasic liquid dosage forms for Internal Use:
1. Syrup:
• It is a concentrated or saturated solution of sucrose in purified water.
• The concentration of sucrose is 66.7% w/w & due to that it is a viscous preparation.
• The syrup which contains medical substance called as medicated syrup & those
containing aromatic or flavored substance known as flavored syrup.
Importance of Syrup:
➢ It retards oxidation because its partly hydrolyzed into reducing sugar.
➢ It prevents decomposition of many vegetable substance because its have high osmotic
pressure which prevent the growth of bacteria.
➢ They are palatable due sweet taste.
2. Elixirs:
• It is clear, sweetened, aromatic, hydroalcoholic preparations meant for oral use.
• The medicated elixirs are generally contained potent drug like as antibiotics,
antihistamine or sedative, where as non – medicated elixirs contained flavored.
• The composition of elixirs contained mainly as ethyl alcohol (active ingredients),
water, glycerin or propylene glycol, colouring agent, flavouring agent & preservative.
3. Linctuses:
• These are viscous liquid preparations that are used for the treatment of cough.
• They contain medicaments which have demulcent, sedative, expectorant action.
• They are taken in small doses without diluting with water to have prolonged effect of
medicines.
• Simple syrup is used as a vehicle for most of the linctuses.

11. • Tolu syrup is preferred in certain cases because of its aromatic odour & flavor.
Moreover it has a mild expectorant action.
4. Drops:
• These are liquid preparations meant for oral administration.
• The oil soluble vitamins, such as vitamin A & D concentrates in fish – liver oil are
presented as drops for administration.
• Since these preparations contain potent medicaments, the dose must be measured
accurately
• The following two methods are commonly used for this purpose.
• Use of a dropper which is accurately graduated in fractions of milliliters.
• Use of a pre – calibrated dropper.
Monophasic Liquid Dosage Forms For External Use:
1. Liniments:
• Liniments are liquid or semi- liquid preparations meant for external application to the
skin.
• They are usually applied to the skin with friction & rubbing of the skin.
• Are usually alcoholic and oily liquid preparations (monophasic) or emulsion
(biphasic).
• Alcoholic liniments are used generally for their rubefacient and counterirritant effects.
Such liniments penetrate the skin more readily than do those with an oil base.
• The oily liniments are milder in their action and may function solely as protective
coatings
• Liniments should not be applied to skin that are bruised or broken.
2. Lotions:
• Are usually aqueous, alcoholic or oily liquid preparations.
• They are intended for external application without friction or rubbing to the affected
area
• Usually applied with the help of some absorbent material such as cotton wool or
gauze.
• It is generally used to provide cooling, soothing and protective & antiseptic action.
3. Gargles:
• Gargles are aqueous solutions used for treating throat infection (pharynx and
nasopharynx part)
• Supplied in concentrated forms with directions of dilution with warm water before use
• They are used into intimate contact with the mucous membrane of throat for few
seconds, before they are thrown out of the mouth.

12. • They are used to relieve soreness in mild throat infection.
• They are also used for their antiseptics, antibiotics and/or anesthetics
4. Mouth Wash:
• These are aqueous solutions with pleasant or acceptable taste & odour
• These are used to make clean & de-odorize the buccal cavity or used for oral hygiene
and to treat infections of the mouth.
• They mainly contain antibacterial agent, alcohol, glycerin, sweetening agent,
flavoring agent & colouring agent.
5. Throat Paints:
• Throat paints are viscous liquid preparations used for mouth and throat infections
• Glycerin is commonly used as a base because being viscous it adheres to mucous
membrane for long period and it possesses a sweet taste.
6. Sprays:
• These are the preparations of drugs in media which may be aqueous, alcoholic, or
glycerin.
• They are applied to the mucous membrane of throat or nose with an atomizer.
• The throat sprays must be sprayed from a special type of atomizer known as a
nebulizer, which removes the large droplets by baffling system.
• Only precaution should be taken that the fine droplet will used to easily reach the
lungs.
7. Inhalations:
• These are liquid preparations containing volatile substance & are used to relieve
decongestion & inflammations of respiratory tract.
• The volatile substance in inhalations would be volatile at room temperature so that
they should be placed on some adsorbent pad or handkerchief.
• In some cases inhalations will added to hot water (650
c) then vapors will inhaled.
8. Nasal Drops:
• Drugs in solution may be instilled into the nose from a dropper or from a plastic
squeeze bottle.
• The drug may have a local effect, e.g. antihistamine, decongestant.
• Alternatively the drug may be absorbed through the nasal mucosa to exert a systemic
effect.
• The use of oily nasal drops should be avoided because of possible damage to the cilia
of the nasal mucosa & if it is used for long period may reach the lungs & cause lipoid
pneumonia.

13. • To avoid that Nasal drops are prepared so that they are similar in many respects to
nasal secretions, so that normal ciliary action is maintained thus aqueous nasal
solutions usually are isotonic and slightly buffered to maintain a pH of 5.5 to 6.5.
9. Eye Drops:
• Sterile, aqueous/oily solutions or suspensions intended for instillation in eye sac.
• Eye drops may contain buffers, stabilizing agents, dispersing agents, solubilising
agents, anti-oxidants & agents required for tonicity/ viscosity adjustment
• Single dose container should not contain anti-microbial preservative.
• In case of multi dose container a dropper should be supplied with it for
administration. Maximum size of such containers is 10 ml.
10. Eye Lotions:
• These are the aqueous solutions used for washing the eyes.
• These are supplied in concentrated forms & are required to diluted with warm water
immediately before use.
• They should be free from foreign particles to avoid irritation to the eye.
• They are required to prepare fresh & should not be stored for more than two days to
avoid microbial contaminations.
11. Ear Drops:
• These are the solutions of drugs that are instilled into ear cavity with the help of
dropper.
• These are generally used for cleaning the ear, softening the wax & for treating the
mild infections.
• The solutions are generally prepared in water, glycerin, propylene glycol & dilute
alcohol.
Biphasic Liquid Dosage Forms:
• The liquid which consist of two phases are known as a biphasic liquid dosage forms.
• They are sub categorized into two different forms such as emulsions and suspensions.
• In emulsion both phases are available in liquid where as in suspension, finely divided
solid particles are suspended in liquid medium.
Emulsion:
• Emulsion is a biphasic liquid preparation containing two immiscible liquid
(Continuous Phase & dispersed phase) made miscible.
• The liquid which is converted into minute globules is called as dispersed phase & the
liquid in which the globules are dispersed is called the continuous phase

14. • An emulsion is a thermodynamically unstable system consisting of at least two
immiscible liquid phases one of which is dispersed as globules in the other liquid
phase stabilized by a third substance called emulsifying agent.
• The globule size in emulsion varies from 0.25 to 25 µm.
• Examples for emulsions:- milk, rubber latex, crude oil etc.
A. Two immiscible liquids not emulsified
B. An emulsion of phase B dispersed in Phase A
C. Unstable emulsion slowly separates.
D. The emulsifying agent (black film) places itself on the interface between phase A
and phase B and stabilizes the emulsion.
Types of Emulsions:
• Simple type
o Water in oil (w/o)
o Oil in water (o/w)
• Depending on globule size
o Micro emulsion
o Fine emulsion
o Special type
• Multiple emulsion (w/o/w, o/w/o)
Water in Oil (w/o):
• In this types of emulsion water is dispersed phase & oil is continuous phase
• w/o types of emulsion generally meant for External use.
• Examples are butter, lotions, creams etc.
• In rare case they are used internally.
Oil in Water (o/w):
• In this types of emulsion oil is dispersed phase & water is continuous phase
• o/w types of emulsion meant for both Internal use & External use.
• Examples for internal use are Vitamin A in corn oil, liquid paraffin in water etc.
• Examples for External use are Benzyl benzonate emulsion.
Micro Emulsion:

15. • These are clear dispersions of o/w or w/o in which the globules have small size like as
a 10nm or 0.01 µm..
• Being cleared products micro emulsion are more popular now a days.
• Micro emulsions are thermodynamically stable optically transparent, mixtures of
biphasic oil –water system stabilized with surfactants.
Fine Emulsion:
• Normally these have a milky appearance.
• The globule size ranges from 0.25 to 25 µm.
Multiple Emulsions:
• These are emulsion with in emulsion & designated as w/o/w or o/w/o.
• The drug that is incorporated in the innermost phase must cross two phase boundaries
before getting absorbed.
• It is generally used in oral sustained release or intramuscular therapy.
Identification Tests:
1. Dilution test: The emulsion is diluted with water, after dilution emulsion remains stable
then it is said to be o/w type of emulsion because water is in continuous phase. If emulsion is
break after dilution with water then it is said to be w/o type of emulsion.
2. Conductivity test: Conductivity test can be performed by dipping a pair of electrode
connecting with low voltage bulb & pass the current. If bulb glows then it is said to be o/w
type of emulsion because water is in continuous phase & it is good conductor of electricity. If
bulb doesn't glow then it is said to be w/o type of emulsion because oil is bad conductor f
electricity.
3. Dye test: Oil soluble Scarlet red dye is mixed with emulsion. Place a drop of emulsion on
microscopic slide cover it with cover slip & examine under microscope. If disperse globules
appears red & ground is colourless then it said to be o/w type of emulsion because water is
present in continuous phase. If reserve condition occurs (If disperse globules appears
colourless & ground is red colour then it said to be w/o type of emulsion because oil is
present in continuous phase.)
4. Fluorescence test: Certain fixed oil posses the physical properties of fluorescing in the
presence of ultraviolet radiations. If examine under microscope ground is fluorescence then it
said to be w/o type of emulsion because oil is present in continuous phase. If examine under
microscope droplet is fluorescence then it said to be o/w type of emulsion because oil is
present in disperse phase.
5. Creaming Test: The direction of creaming identifies the emulsion type, if the densities of
aqueous and oil phases are known. Water-in-oil emulsions normally cream downward as oil
is usually less dense than water. Oil-in-water emulsions normally cream upwards.

16. 6. Cobalt chloride test: Pour the emulsion on filter paper then it is soaked in cobalt
chloride solutions & allowed to dry turns from blue to pink. Then this emulsion is said to be
o/w type of emulsion. This test may fail if emulsion unstable or breaks in presence of
electrolyte.
7. Filter paper test: This test is based on the fact that an o/w emulsion will spread out
rapidly when dropped onto filter paper. In contrast, a w/o emulsion will migrate only slowly.
This method should not be used for highly viscous creams.
Suspension:
• Suspensions are the biphasic liquid dosage forms of medicament in which finely
divided solid particles ranging from 0.5 to 5 micron are dispersed in a liquid or
semisolid vehicle, with aid of single or combination of suspending agent.
• In which solid particles acts as disperse phase where as liquid vehicle acts as
continuous phase
• The external phase (suspending medium) is generally aqueous in some instance, may
be an organic or oily liquid for non oral use.
• The particle size for non oral suspension is so important to avoid grittiness to skin.
Advantages of Suspension:
• Suspension can improve chemical stability of certain drug. E.g. Procaine penicillin
• Drug in suspension exhibits higher rate of bioavailability than other dosage forms.
Solution > Suspension > Capsule > Compressed Tablet > Coated tablet
• Duration and onset of action can be controlled. E.g. Protamine Zinc-Insulin
suspension.
• Suspension can mask the unpleasant/ bitter taste of drug. E.g. Chloramphenicol
Disadvantages of Suspension:
• Physical stability, sedimentation and compaction can causes problems.
• It is difficult to formulate.
• Uniform and accurate dose cannot be achieved unless suspension is packed in unit
dosage form.
• All suspensions are required to be shaken before measuring of dose.
• The storage of suspension may lead to changes in disperse system especially, when
there are fluctuations in temperatures.
Ideal Qualities of a Good Suspension:
• It should settle slowly & easily re – dispersed on shaking
• It should readily & evenly pour from container.
• It should be chemically inert.
• It should not form hard cake.

17. • It should prevent degradation of drug or to improve stability of drug.
• It should mask the taste of bitter of unpleasant drug.
Flocculated Suspension:
• In this type, solid particles are loosely aggregates themselves, means individual
particles are come in contact with each other to forms network like structure called as
floccules.
• These flocks are light, fluffy in nature, which are held together by weak van der
Waals force of attraction.
• Aggregation is achieved by adding flocculating agent.
• These suspensions will readily sediments.
• This suspension possesses better physical stability but less bioavailability as
compared to deflocculated suspension due to dissolution of floccules.
Deflocculated Suspension:
• In this type of suspension, individual particle exits as a separate entity, means
particles carry finite charges on their surface. Hence particles approaches each other,
they experience repulsive forces. This force creates a high potential barrier, which
prevents a aggregation of particles.
• During storage, these suspension shows a sedimentation at slow rate, due to that
particles forms a close packing arrangement.
• So that it is difficult to re-dispersed on agitation & forms a cake or claying which is
hard in nature.
• This type of suspension has shorter shelf life but high bioavailability as compared to
flocculated suspension.
Flocculated Suspension Deflocculated suspension
Particles form loose aggregates & forms
network like structure.
Particle exists as separate entities.
Particles experience attractive forces. Particles experience repulsive forces.
Supernatant liquid is clear. Supernatant liquid is cloudy.
The rate of sediment is high. The rate of sediment is slow.
Sediment is rapidly formed. Sediment is slowly formed.
Sediments are loosely packed; hence
hard cake is not formed.
Sediments are closely packed, hence hard cake is
formed.
The sediment is easy to re-disperse on
shaking.
Sediment is difficult to re-disperse on shaking.
(due to formation of hard cake)
Bioavailability is comparatively less. Bioavailability is relatively high.
The suspension is not pleasing in
appearance.
The suspension is pleasing in appearance.
Volume/weight for estimation of dose of liquid dosage forms:
Dosing measure Aprox. Volume (ml) Aprox. Weight (g)

18. 1 drop 0.05 0.05
1 teaspoonful 5 5
1 tablespoonful 15 15
20 drops of aqueous solution 1 1
60 drops of ethanolic solution 1.25 1
SEMI-SOLID DOSAGE FORM:
• Semisolid dosage forms meant for external application
• Semisolid dosage forms subcategorized are as:
o Ointment
o Creams
o Paste
o Jellies
o Suppositories
• The suppositories are also included in this category but it is a unit dosage forms.
Ointment:
• Ointments are semisolid preparation meant for application to skin or mucous
membrane.
• The ointments are mainly used for their protective or emollient properties
• It may be defined as a medicament or medicaments dissolved, suspended or
emulsified in ointment base.
• There is no single ointment base which possesses all the qualities of ideal ointment
base, so it becomes necessary to use more than one ointment base in the preparation
of ointment.
Qualities of an Ideal Ointment Base:
• It should be inert, odorless & colourless & smooth.
• It should be physically & chemically stable.
• It should be compatible with the skin & with incorporated medicaments.

19. • It should be of such consistency that it spread & soften when applied to skin with
stress.
• It should not retard healing of wound.
• It should produce irritation or sensitization of the skin.
Classification of Ointment Base:
• Oleaginous bases
• Absorption bases
• Emulsion bases
• Water soluble bases
Oleaginous Base:
• These bases consist of water soluble hydrocarbons, vegetable oils, animal fats & wax.
• The constituents of hydrocarbon bases are soft paraffin, hard paraffin & liquid
paraffin.
• The vegetable oils are mainly used in ointment to lower the melting point or to soften
the bases.
• These bases serve to keep the medicaments in prolonged contact with the skin & also
act as occlusive dressings. They have a low capacity to absorb water & are used
chiefly for their emollient effect.
• These bases losing their importance now a days for the many reason.
Disadvantages of Oleaginous bases:
• They are greasy.
• They are sticky & are difficult to remove both from skin & clothing.
• They retain body heat which may produce an uncomfortable feeling of warmth.
• They do not help in the absorption of medicaments.
Absorption Bases:
• These bases are generally anhydrous substance which has the property of absorbing
considerable quantities of water but still retaining their ointment like consistency.
• The absorption bases are of two type namely as
o Non-emulsified bases
o Water in oil emulsion
• Non emulsified bases absorb water & aqueous solutions producing w/o emulsion. E.g.
Wool fat, wool alcohol, beeswax & cholesterol.
• Water in oil emulsions are capable of absorbing more water & have the properties of
non- emulsified bases. E.g. hydrous wool fat (lanoline)
Emulsion Bases:
• These bases are semisolid or have cream like consistency.

20. • Both o/w or w/o emulsions are used as a ointment base.
• The o/w emulsion base is more popular now days because ease of application will
easily achieved.
• The w/o type of emulsion bases are greasy & sticky.
• The emulsifying ointment is prepared from emulsifying wax, white soft paraffin &
liquid paraffin.
Water Soluble Bases:
• These are commonly known as greaseless ointment bases.
• The water soluble bases consist of water soluble ingredients such as carbowaxes (
polyethylene glycol polymer)
• The carbowaxes are water soluble, non – volatile & inert substance.
• Selection of appropriate carbowaxes is depend on their molecular weight.
Creams:
• These are viscous semisolid emulsions which are meant for external use.
• Cream is divided in to two types namely as
o Aqueous creams
o Oily creams
• In case of aqueous creams the emulsions are o/w type & it is relatively non greasy.
The emulsifying waxes are anionic, cationic & non–ionic used. Generally
polysorbate, triethanolamine soap are used as emulsifying agent.
• In case of oily creams w/o type & it is relatively greasy. The emulsifying agent such
as wool fat, wool alcohols, and beeswax and calcium soap is used.
• The cream should be store in collapsible tube & supplied in well closed container to
prevent evaporation & contamination.
Pastes:
• Pastes are semisolid preparations intended for external application to skin.
• The pastes are generally very thick & stiff.
• They do not melt at ordinary temperature & thus forms a protective coating over the
area where they are applied.
• Pastes differ from ointment as they contain a high proportion of finely powdered
medicaments.
• They are mainly used as antiseptic, protective, soothing dressings.
• Pastes should be stored & supplied in containers made of materials which do not
allow absorption or diffusion of content.
Jellies:

21. • Jellies are transparent or translucent, non greasy, semi solid preparations mainly used
for external application to skin.
• These are also used for lubricating catheters, surgical gloves & rectal thermometer.
• The substance like gelatin, starch, tragacanth, sodium alginate & cellulose derivatives
are used for the formulation of jellies.
• Jellies are of three types namely as medicated jellies, lubricating jellies and
Miscellaneous jellies.
NEW DRUG DELIVERY SYSTEMS:
With the advancement of pharmaceutical sciences, a new concept has evolved various
modern dosage forms & methods of their administration. Some of the modern dosage forms
are:
• Implants
• Films & strips
• Liposome drug carriers
• Controlled drug delivery modules
• Erythrocytes
• Nanoparticles
• Prodrugs
Implants:
• These are hypodermic tablets are placed under the skin by a minor surgery in order to
release drugs over prolonged periods of time.
• Now the magnetically controlled implants have been developed which can be opened
or closed at will in order to release or stop the drug.
• These implants are placed at upper thigh at a depth of 5mm.
• These implants are useful in hormone therapy.
Films and Strips:
These are meant for topical application for slow release of drug over predetermined
period of time. Films & strips are more popular these days. They are sub categorized in to
following types namely as:
• Zero order release films
• Buccal strips
• Spray bandages
1. Zero Order Release Films:
• These are called as laminates & meant for topical application. E.g.

22. • Nitroglycerine laminates are prepared by mixing propylene glycol with about 1%
carbopol resin. The mixture is neutralized with NaoH solution & then 0.1% of
nitroglycerin is added. It is then placed in polythene sheet 5*5 cm & its edges are
sealed by heat. It is then placed on pressure sensitive adhesive sheet of 5.5 * 5.5 cm
so that it can be properly adhesive to skin. Such laminates release the drug slowly into
circulation for about 12 hours.
2. Buccal Strips:
• The buccal & sublingual tablets are now replaced with buccal strips.
• These strips consist of a thin absorbent base of fabrics, filter paper & cotton etc.
• The buccal strips are prepared by immersing a long piece of fabric made from
polyamide fibers into a molten mixture of carbowaxes & dissolved or dispersed the
drug.
• The fabric is then cooled & cut into small pieces.
• It should be contact with buccal mucosa for about 15 min. & then removed &
discarded.
3. Spray Bandage:
• These bandage are prepared by spraying the solution of drug in polylactide (polymer
of lactic acid anhydride)
• A solution of purified lactide polymer is made in chloroform.
• It is then packed in aerosol container having suitable propellant.
• When these solutions sprayed then it will be a comfortable bandage which can simply
washed off with warm water.
Liposome Drug Carriers:
• These are several carriers in our body which transport both to an other like as
enzymes, proteins etc.
• These are phospholipids which can transport both hydrophilic & hydrophobic drugs.
• The large multilamellar vesicles (LMV), small unilamellar vesicles (SUV), large
unilamellar vesicles (LUV) are some of the liposome's known today.
Applications:
• Used in diseases caused by intracellular parasites. E.g. malaria, tuberculosis &
amoebiasis.
• It entrapped insulin is active orally & can be replaced by IM administration of insulin.
• It can be used to transport functional DNA/RNA molecules into cell.
• It can be used to transport radio pharmaceuticals & immunological products.
• Liposomal daunomycin has longer duration of action than free daunomycin which is
used in the treatment of neoplasia.

23. Controlled Drug Delivery Modules:
• These are the devices which are formed by embedding the drug within a polymeric
matrix so that it gets released slowly to the body over a long period of time.
• It will formed drug – polymer complex & may be formulated in to tablet, capsule or
any other suitable formulation.
• These modules are punctured before administration with laser beam to make a small
orifice for release of the drugs.
• The drug is released from these modules by diffusion, osmosis or chemical reactions.
• These are applied to skin, implanted subcutaneously or inserted into various body
cavities.
Erythrocytes:
• Erythrocytes are tried in order to achieve controlled release of drugs.
• The life spans of erythrocytes are 120 days.
• It can allow a drug to circulate in the body for long period of time which helps slow
release of the drugs in to serum.
• Released erythrocytes are prepared by putting them in to a hypotonic medium. So that
they can easily swollen.
• The aqueous solutions of the drug are added to the medium so that drugs get in to
erythrocytes through open pores.
• When isotonicity is adjusted the erythrocytes shrink, thus encapsulating the drug
within them. These erythrocytes may be suspended in normal saline solutions for
preparing injections.
Applications:
• Released erythrocytes of urease have been used in kidney failure to degrade serum
urea.
• Released erythrocytes of asparaginase have shown good result in asparaginase
dependent leukemia.
• Released erythrocytes of methotrexate & adrianycin have been tried in cancer therapy.
• Released erythrocytes of prednisolone have shown good result to prolong the anti-
inflammatory action.
Nanoparticles:
• It is based on colloidal drug delivery system.
• The particles size of this system is in nanometer range (200 – 500 mm)
• The system consists of a drug & carriers to deposit the drug at target site.
• The carriers used are naturally occurring macromolecules like human serum albumin,
bovine serum albumin, & other substances like gelatin, casein & ethylcellulose.

24. Applications:
• Flourescein isothinocyanate (FITC) nanoparticles have been used to incorporate
cytotoxic agent into tumor cell in cancer chemotherapy.
• Nanoparticles along with biological maker like immunoglobulin can be used to target
the drugs to very specific site.
Prodrugs:
• The compounds which undergo biotransformation before showing desired
pharmacological activity are called prodrugs or proagents.
• Prodrugs are generally the ester or amides of parent drugs.
• These are useful to improving the stability, solubility, bioavailability of drugs,
masking the unpleasant taste & odour of the parent drug & reducing the toxicity
Applications:
• Choramphenicol palmitate, the prodrug of chloramphenicol is used in the preparation
of pediatrics suspension because it has no bitter taste.
• Procaine penicillin G & benzathine penicillin G are prodrugs of penicillin G which
shows resistance to hydrolysis as compared to the parent drug.
• Cindamycin 2- phosphate the prodrug of cindamycin has no bitter taste of parent drug.