This document provides information about semisolid dosage forms such as ointments, pastes, creams, and gels. It defines these terms and discusses the anatomy of skin, factors affecting drug penetration through skin, and formulation and evaluation of semisolid dosage forms. The document covers the stratum corneum as the major barrier to drug penetration, routes of penetration, and biological and physicochemical factors influencing penetration. It also describes various ointment bases including oleaginous, absorption, emulsion, and water soluble bases and provides examples of each.

1. SEMISOLIDDOSAGE
FORMS
Presented By:
Mr.Naresh Gorantla, M.Pharm, (Ph.D)
Assoc. Professor,
Departmernt of Pharmaceutics
Balaji college of pharmacy, Anantapuramu

2. CONTENTS
• Introduction
• Anatomy of skin
• Routes of drug transport
• Factors affecting penetration
• Formulation
• Manufacturing
• Evaluation

4. DEFINITIONS
1.OINTMENT: These are semi solid preparations meant for
external application to the skin/ mucous membrane.
2.PASTE: These are semisolid preparations containing high amounts
of solid ingredients intended for external application to skin.
3.CREAM: These are viscous semisolid emulsions meant for
external use.
4.GELS: These are semisolid aqueous dispersion systems which may
contain suspension of either small /large organic molecules dispersed in
a suitable liquid.

5. The skin is very effective as a selective penetration barrier. The
epidermis provides the major control element for drug penetration.

6. A. Epidermis
The superficial, thinner portion composed of keratinized stratified
squamous epithelial tissue
 Epidermis consists of different layers
a) Stratum corneum (Horney layer)
Barrier to Percutaneous absorption
b) Stratum lucidum (Barrier zone)
 Barrier to transfer of water across skin,
 damage resulted in increased permeability.
c) Stratum granulosum (Granular layer)
 Participate in keratinisation
d) Stratum spinosum
e) Stratum basale (Stratum germinativum)
 Melanocytes the pigment-producing cells of the epidermis,

7. B. Dermis :
The sensitive connective tissue layer of the skin located below the
epidermis, containing nerve endings, sweat and sebaceous glands,
and blood, hair follicles, fibroblast, histocytes and lymph vessels.
Composed of strong connective tissue containing collagen (for
strength) and elastin (for stretch )
Play major role in temperature regulation.

8. Hypodermis (SC fatty layer)
Below the dermis is hypodermis also called
subcutaneous layer.
Sub mean under and cutaneous mean skin.
Loose layer of connective tissue which is anchored
to the underlined tissue ( muscle and bones).
Most fat cells are present in hypodermis (adipose
tissues)
 acts as insulator to protect the body from excessive heat
and cold environment

9. Skin appendages
1.Sweat glands
The sweat glands are coiled tubules in the dermis which
open on to the skin surface; they can be sub-divided in to
two classes;
• Eccrine glands:
 The sweat glands which are involved in the regulation
of body temperature by water elimination.
 About two million eccrine sweat glands
• Apocrine sweat glands:
 Are larger than eccrine sweat but few in number.
They are mainly located in the hairier regions of the
maxillae and around the nipples.
Apocrine sweat differs in composition from eccrine
and may be cloudy and colored

10. 2.Hair follicles
Hair follicles are sebum-filled openings from which keratinous
hair filaments protrude.
 Follicles occupy about 0.1% of the skin surface area;
 absent from plantar and palmar surfaces, the red areas of the
lips, and parts of the genitalia.
2.Sebaceous glands:
 More in number and size on face
 Palms, soles doesnot contain Sebaceous glands
 Sebum is composed of Glycerides, Free fatty acids,
Cholesterol, Cholesterol esters, wax esters and
Squalene.

11. Mechanism of drug penetration through skin
Three potential entry routes of drugs to the viable
tissue:
1.Transepidermal route (Across the continuous
stratum corneum)
2.Transappendageal route
3.Epidermal route

12. Transepidermal route
• Polar pathway
• When the therapy is required to target horny layer of the
skin
• Emollients and Exfolients
• Diffusion is passive process i.e. follows concentration
gradient.
• Low molecular weight molecules penetrate through
stratum corneum to some extent.

13. Transepidermal route
• Intrafollicular pathway
• For ions and large molecules with low diffusion
coefficients which crosses S.Corneum with difficulty
(Polar steroids and antibiotics)
• Antiperspirants like Aluminium chloride
• Topical Antibiotics like Tetracycline, Clindamycin
• Antifungals like Clotrimazole, Miconazole
• Depilatories like Strontium sulphide, Barium sulphide
and Thioglycolates.
• Topical exfolients like Salicylic acid, Retinoic acid

14. Epidermal route
• Intercellular pathway
• Drugs like Topical steroids, NSAIDs and
corticosteroids
• Anaesthetics like Benzocaine
• Antihistamines and Antipruritics
• Antimalignants like Methotrexate, 5-flouro
uracil

15. Low molecular weight molecules penetrate through stratum coneum
to some extent.
Skin appendages are main route for Electrolytes, polar steroids,
antibiotics and colloidal particles.
Particles of 3-10 µm can penetrate through hair follicle and
particles less than 3µ penetrate through stratum coneum.
Hair follicle route may be important for ions and large polar
molecules.
Topically applied agents such as steroids, hexachlorophane,
griseofulvin, sodium fusidate and fusidic acid may form a depot or
reservoir by binding within the stratum corneum.

16. Once drug permeates through horny layer it readily enters living tissue
and systemic circulation.
The average residence time of drug in dermis may be 1 min before it
is washed away by blood.
NSAIDS reach far down to muscles to form depots.

17. Factors influencing dermal penetration of drugs
I. Biological factors:
1. Skin condition
2. Skin age
3. Blood flow
4. Regional skin site
5. Moisture content
and environmental
temperature
II. Physicochemical factors:
1. Drug-skin
1. Skin hydration
2. Drug-skin binding
2. Vehicle -skin
1. Type/Nature of vehicle
2. Temperature
3. Penetration enhancers
3. Drug - Vehicle

18. BIOLOGICAL FACTORS:
1. Skin condition: Injuries, Chemicals and Defatting.
The intact, healthy skin is a tough barrier but acids and alkalis
injure barrier cells and thereby promote penetration.
Mixtures of non-polar and polar solvents, such as chloroform and
methanol, remove the lipid fraction and molecules pass more easily.
Disease alters skin condition, skin inflamed, with loss of stratum
corneum thus permeability increases.
2. Skin age
Skin of the young and the elderly is more permeable than adult
tissue.
Children are more susceptible to the toxic effects of drugs and
chemicals, because of their greater surface area per unit body
weight; thus potent topical steroids, Causes severe side-effects and
death.

19. 3.Blood flow:
An increased blood flow could reduce the amount of time a
penetrant remains in the dermis, and also raise the concentration
gradient across the skin.
4. Regional skin sites :
Variations in permeability depend on the
 thickness and nature of the stratum corneum and
 the density of skin appendages.
Permeabilities depend on thickness of stratum corneum and the
overall thickness of the tissue.
Facial skin in general is more permeable than other body sites

20. 5. Moisture content of Skin and environmental temperature:
If the moisture content of the skin is high then penetration is also
high.
When the drugs are applied to a completely hydrated skin, their
penetration rates are high.
 Environmental temperature also affects the drug absorption
through skin, drugs like Aspirin and glucocorticoids absorbs 10
times faster at 37 c than at 10 c.

21. Physicochemical factors: Drug-skin interactions
1. Skin hydration:
When water saturates the skin the tissue swells, softens
and wrinkles and hydration of the stratum corneum
increases permeability.
A compound which hydrates the skin efficiently
can also improves penetration.
Substances like free fatty acids, pyrrolidone
carboxylic acids, urea, sodium, potassium and
calcium lactates are used as natural moisturizers.
Dusting powders or lotions, provide a large surface
area for evaporation and therefore dry the skin.

22. Physicochemical factors
2. Drug - Skin Binding:
Drugs which are having binding capacity with skin and skin
constituents also affects the penetration.
Drugs like Surface active agents, Sunscreens and
some topical steroids bind with skin and form
reservoirs in the s.corneum and releases slowly.

23. Physicochemical factors: Vehicle-skin interactions
1. Type and Nature of the vehicle:
Occlusive vehicles like fats and oils reduces water loss,
increases moisture content and promotes penetration.
Lipophilic vehicles like paraffins, waxes, fatty acids, and
alcohols also prevents water loss.
W/O emulsions are also occlusive in nature.
O/W emulsions are slightly less occlusive but also
promotes penetration.
2. Effect of Temperature:
 Increased temperature can increases
penetration.
 Occlusive vehicles can increase temperature on
application.
 Minor effect compared to hydration.

24. 3. Effect of penetration enhancers:
Substances which temporarily diminishes the impermeability of the
skin and enhances the penetration rate of drugs are called as
penetration enhancers.
DMSO, DMF and DMA commonly used but have irritant effect,
toxicity and bad odor.
Pyrrolidones can be used as effective enhancers.
Surfactants especially anionic surfactants alters the penetration by
interacting with protein helics of the skin.
Combination of oleic acid with propylene glycol.
Considering the safety and effectivity water is the best penetration
enhancer.

25. Physicochemical factors: Drug – Vehicle interactions
This factor is considered when release of drug from the
vehicle is the rate determining factor.
The affinity between the drugs and the base determines
the release rate of drugs.
The substances having lower solubility in the vehicle may
releases rapidly.

26. Ointments
DEF: Ointments are semisolid preparations meant for external
application to skin or mucous membrane.
FORMULATION OF OINTMENTS:
1. Active pharmaceutical ingredients
2. Ointment bases
3. Antioxidants
4. Preservatives
5. Humectants
6. Perfumes

27. Classification of ointments
1. Based on penetration
•Epidermic- Meant for action on epidermis
•Endodermic- Action on deeper layers of cutaneous tissue
•Diadermic- Meant for deep penetration
2. According to therapeutic uses (API)
• Antieczematous like Hydrocortisone, coal tar and Ichthammol.
• Antibiotics like Bacitracin, Neomycin
• Antifungals like Benzoic acid, salicylic acid, Nystatin
• Antiinflammatory like Betammethasone, Triamcenolone
• Antipruritics like Benzocaine, coaltar
• Astringents like calamine, Zinc oxide and Tannic acid
• Counter irritants like Capsaicin, Iodine, Methyl salicylate
• Keratolytics like Resorcinol, Salicylic acid and Sulphur
• Paraciticides like Benzyl benzoate, Gamma benzene hexa
chloride.

28. An ointment is a substance or part of an ointment which
serves as a carrier or vehicle for the active ingredient.
They should be:
 Compatible with skin pH and drug
 Inert, non irritating and non sensitizing
 Good solvent and/or emulsifying agent
Emollient, protective, non greasy and easily
removable
Release medicaments easily at the site of
administration
 Pharmaceutical elegant and possess good stability.

29. BASES
OLEAGINOUS
BASE
ABSORPTION
BASE
EMULSION
BASE
WATER
SOLUBLE
BASE

30. 1.Oleaginous(hydrocarbon)bases:
They consist of a combination of more than one oleaginous
material such as water insoluble hydrophobic oils and fats
Disadvantages:
• Greasy, sticky-non washable
• Retain body heat
• Do not increase absorption
• They are anhydrous, do not absorb water & insoluble in water.
• Emollient action on skin.
These bases include:
1. Hard Paraffin,
2. Soft paraffin,
3. Liquid paraffin

31. A) Hard paraffin:
 A mixture of solid saturated hydrocarbons that are derived from
petroleum.
 It is a colourless or white wax-like material that is physically
composed of a mixture of microcrystal.
 The melting temperature of hard paraffin is between 47 and 65oc
and,
 used to enhance the properties of ointment bases.
B) Soft paraffin (Petrolatum):
This is purified mixture of semisolid hydrocarbons obtained from
petroleum.
Types
1. Yellow soft paraffin – M.pt=380C, used in ophthalmic ointments.
2. White soft paraffin- M.pt=560C, obtained from bleaching Yellow
soft paraffin.

32. c) Liquid paraffin (white mineral oil/ liquid petroleum):
mixture of liquid hydrocarbons obtained from petroleum
by distillation.
 White, transparent, tasteless, oily liquid.
USE- Combine with hard/ soft paraffin to harden/soften
ointment base, and also as levigating agent.

33. 2.Absorption bases:
Absorption bases, unlike the hydrocarbon types, are
hydrophilic-absorb considerable amounts of water or
aqueous solutions.
These bases do not absorb water on contact, but with
sufficient agitation, they absorb aqueous solutions and may
become W/O type emulsions.
Less occlusive than hydrocarbon bases, but have
emollient action.
Not easily removable from skin.
To incorporate small amounts of aqueous solutions.

34. 1. Wool fat(Anhydrous lanolin):
This is fat from wool of sheep ovis aries
Can absorb 50% water of its weight., more sticky nature.
USE: ointment base preparation, ophthalmic ointments.
2. Wool alcohol:
Wool fat is alkalized to separate cholesterol & alcohol.
It contains NLT 30 % of cholesterol.
USE: ointment base preparation
3. Bees wax:
Wax from honey comb of bees.
2 types- yellow & white bees wax
USE: stiffening agent in paste & ointments.
4. Hydrous wool fat:
Purified fat from wool of sheep.
Insoluble in water, soluble in ether, chloroform.
Contains 70% wool fat+ 30% water.
USE: Emollient.

35. Advantages of Absorption bases
Compatible with most of the medicaments
Absorb large quantity of water or aqueous substances
Relatively heat stable
Easily spreadable
Less occlusive and good emollients
Aqueous substances can be incorporated
Disadvantages
Undesirable due to greasy nature
Chances of microbial contamination.

36. 3. WaterRemovable bases:
 Water removable bases and are of O/W emulsions that resembles
creams in appearance.
 Ability to absorb water, serum discharges.
 Can be diluted with water.
Advantages:
Miscible with exudates from lesions
Does not interfere with skin function
Good contact with skin because of surfactant content
High cosmetic acceptability.
Easy removable from the hair.

37. Hydrophilic ointment:
White petrolatum 250 gm
Stearyl alcohol 250 gm
Propylene glycol 120 gm
SLS 10 gm
Methyl Paraben 0.25 gm
Propyl paraben 0.25 gm
Purified water 370 gm

38. 4.WatersolubleBases: (Greaseless Base)
 Do not contain oleagenous substances and contain completely
water soluble ingredients.
 Greaseless and become softer on addition of water.
1. Carbowaxes 200,300…1500. (For viscous liquids)
2. Carbo waxes 1540, 3000.. 6000(For Viscous solids)
3. Pectin, Tragacanth & Cellulose derivatives (Form plants)
4. Gelatin (Animal)
5. Silica Gel, Bentonite (Chemical)
6. For low viscosity - Glycerin, Glyceryl mono stearate.

39. Carbo waxes (Macrogols/ Polyethylene glycols)
General formula CH2OH. (CH2OCH2)n . CH2OH
These are mixtures of polycondensation products of ethylene oxide
and water
•Average Molecular weight is represented by numbers
Macrogols 200, 300, 400
Macrogol 1500
-- viscous liquids
-- greasy semi solid
Macrogols 1540, 3000,4000, 6000 -- waxy solids
Liquids
• Clear and colourless
• Faint characterisitic odour
• Miscible with water, alcohol and other glycols

40. Solids
• White or cream in colour
• Hard lumps or flakes
• Soluble 1 in 3 in water and 1 in 2 in alcohol
• Solidifying points range from 40 to 60°c
Macrogols Properties:
• Non-toxic and non-irritating
• pH – 4 to 7.5
• Can be sterilised by heat (solids – dry heat, liquids – autoclave)
•water soluble, non-volatile and inert substances.
Different carbowax mixture produces different consistency.

41. Selection of an appropriate ointment base
Pharmaceutical Factors
1. Stability
2. Solvent properties
3. Consistency
Dermatological Factors
1. Effect on skin function
2. Miscibility
3. Compatibility
4. Irritation
5. Emolliency
6. Ease of Application &
Removal

42. Formulation of ointments Cont..
Antioxidants:
 When there is a possibility of oxidative degeneration.
 BHT, BHA and propyl gallate.
Preservatives:
 These are selected based on irritancy and toxicity.
 Benzoic acid derivatives are used commonly.
 But for nasal administration they are not used because of irritation,
Quaternary ammonium compounds like Phenyl mercuric nitrite is
used.
Chelating Gents:
 To chelate the trace amounts of metal ions, chelating agents like
Citric acid, Phosphoric acid, Maleic acid, Tartaric acid are used.
Perfumes:
 To give a pleasant odour.

43. MANUFACTURING
Ointments are prepared by
1. Incorporation or Trituration method
2. Fusion method
3. Chemical reaction method
4. Emulsification method

44. Incorporation method
1. Incorporation of solids
2. Incorporation of Liquids
Ointment tile and Spatula made up of metal, rubber are used.
The method involves steps like
Size reduction
Levigation
Trituration
Levigating agents mineral oil for oleagenous bases and Glycerin
for other bases.
Mortar and pestle is used for levigation.
After levigation the paste of the drug is incorporated into
ointment base.
While incorporating liquids, the capacity of base to absorb and
retain liquids must be considered.

45. FUSION METHOD
• When ointment base consists of number of solid ingredients.
• When the melting point differences are more.
• All the ingredients are subjected to heat to melting.
• Melting is done in the decreasing order of the melting points.
• Heat sensitive or any volatile substances are added last.
• Porcelain dish or glass beaker is used in small scale, and Steam
jacketted kettle is used in large scale.

46. EMULSIFICATION METHOD
1. Fats, oils and waxes an melted together to a temperature and 700c.
2. Aqueous solution of the heat stable, water soluble compounds is
also heated to the same temperature.
3. Aqueous Solution is slowly added to the melted bases, with
continuous stirring until cool.
Emulsifying agent is needed to make a stable emulsion
Water soluble soaps are commonly used as emulsifier for semisolid o/w
emulsions.
Combination of triethanolamine stearate soap and cetyl alcohol is used
in o/w emulsion
Bees wax and divalent calcium ions used in w/o emulsion.

47. Chemical reaction method
Preparation of some ointment involves chemical reactions
Eg – (a)Iodine ointment (iodine free form)
(b)Iodine ointment (iodine combined form with ointment base)
(a)Ointments containing free iodine
Iodine is slightly soluble in fats and vegetable oils.
Readily soluble is potassium iodide solution in water due to
formation of polyiodides (KI. I2, KI. 2I2 ,KI.3I2)
Poly iodides are readily soluble in water, alcohol and glycerin.
These solutions may be incorporated with the molten absorption
type ointment base.

48. (b) Ointments containing combined iodine
Fixed oils and many fats obtained from vegetable and animal sources
contain unsaturated constituents
Iodine combines with double bonds
CH3 (CH2)7 CH=CH (CH2)7 COOH + I2 (Oleic acid)
CH3 (CH2)7 CHI.CHI (CH2)7 COOH (Di-iodo stearic acid)
Free iodine is not available, So ointments appear dark, greenish black
in colour
Leaves no stain when rubbed into the skin, Hence known as non-
staining iodine ointment

49. EVALUATION OF OINTMENTS
1.Drug content
2.Release rate of medicament from base
3.Penetration rate of medicament
4.Absorption of medicament into blood stream
5.Consistency of the preparation
6.Irritant effect

50. 1. Drug content:--Minimum fill test
 Select any 10 filled containers
 Weigh the required amount of ointment
 Medicament is extracted into a suitable solvent
 Drug Content is determined by suitable analytical technique
 Results should be with in labeled quantity.
2. Release rate of medicament from base:--
Two in vitro techniques are used
1. Agar cup plate method
2. Diffusion method

51. Agar cup Plate method
• Used to determine the release rate of antibacterial ointment
• Tested in agar medium seeded with staphylococus aures.
• Zone of inhibition of bacterial growth is measured around
circular cups

52. Diffusion method:
Used to find the release rate of any type of medicament from
the base
A semi permeable membrane is tied at one end of glass tube
Ointment is filled in the tube, properly spread on the membrane
Tube is dipped in the distilled water maintained at 37±1OC
Samples are withdrawn after a specified period of time.
Samples are immediately replaced with fresh distilled water
Analyzed for the drug content
Plot a graph between drug concentration and time

54. 3. Penetration rate of medicament:
Determined by rubbing weighed amount into defined areas for a
fixed time.
Unabsorbed material is removed completely and weighed.
Difference in weight provides total amount penetrated.
Rate is then calculated.
4. Absorption of medicament into blood stream:
Diadermic ointments are tested by in-vivo method.
Determined by assaying drug content in either blood, urine, faeces
or tissues after rubbing defined amount under standard conditions

55. 5. Consistency of the preparation:
Determined by sliding a glass plate over the product by means of
a pulley.
Product is spread evenly on another glass plate fixed on a wooden
block.
Weights are added to the pan so that sliding of the movable glass
plate is obtained.
Ointment which require more weights to allow the plate to slide-
over have high consistency or vice-versa.

57. 6. Irritant effect:--
Test is performed on skin and eyes of rabbit or human skin.
Results are observed daily for a week
Irritant effect of dermatological preparation is shown as lesions
on cornea, iris and conjunctiva.
Some times Rats are used and the ointments are injected to thigh
muscles and sometimes under abdominal skin.
Reactions are noted at intervals of 24,48, 72 and 96 hrs.
Irritation can be identified by the presence of
patches on skin.

58. PASTES

59. • Pastes are semisolid preparations intended for application
on to the skin and they differ from ointments that they
generally contain a large amounts of finely powdered
solid substances.
• These are thicker and stiffer than ointments and also less
greasy than ointments and this is due to less amount of
base.
• Stiffer in consistency and do not melt at body
temperature.
• Less viscous than ointments and easy to stick.
• Due to high content of powdered substances pastes can
absorb serous secretions and exudations.

60. Formulation of Pastes
1. API
2. Bases
3. Absorbents
4. Humectants
5. Flavours/Perfumes
6. Stabilizers

61. Paste base:
1. Hydrocarbon bases:-- soft paraffin , liquid paraffin.
2. Water miscible bases:-- glycerin, emulsifying ointment.
3. Water soluble bases:-- poly ethylene glycols.
Absorbents:
To absorb wound exudates and secretions Ex: Zinc oxide, Light kaolin,
Starch etc.
Humectant:
Tomaintain humidity in the preparation and to prevent drying. Ex:
glycerin, sorbital, propylene glycol.

62. GELS

63. GELS
• Gels are thin, transparent or translucent non greasy preparations
consisting of dispersions of small or large molecules in an aqueous
liquid vehicle.
• Lubricating (Surgical), Local anaesthetics, Antiseptic and
Spermicidal (Non surgical) purposes.
• Gels are not suitable for water insoluble drugs.

64. FORMULATION OF GELS
1. Active ingredients: Local anaesthetics,
Antiseptics,
Spermicides- Nanoxynol-9
2. Gelling agents
3. Co-solvents/Dispersing agents
4. Preservatives
5. Water

65. Gelling agents
These are organic hydrocolloids/ hydrophilic inorganic substances.
1. Natural gelling agents– gum tragacanth, Alginates, starch,
pectin, gelatin.
2. Semi synthetic gelling agents – Cellulose derivatives
3. Synthetic gelling agents– Carbomers, poly vinyl alcohol, etc.,

66. 1.Tragacanth :
Used for preparations of Lubricating, Medicated & Contraceptive Jellies.
Concentrations used for Lubricating (2 to 3%) &
Dermatological vehicle (5%).
Tragacanth is poorly wettable
On addition to water lumps are formed which is difficult to disperse
Dispersing agent is generally used to get a homogenous product
Alcohol, glycerol or volatile liquids are used as dispersing agent

67. Disadvantages :
• Obtained from natural sources, so vary in viscosity
• After evaporation, the film left on the skin tends to flake
• Loss of viscosity outside the pH range of 4.5 – 7
• Can’t be stored for longer time
• Prone to microbial growth

68. • 1.5 to 2% Used as Lubricant gel & Dermatological vehicle 5 To 10%
• Viscosity can be increased by adding soluble calcium salt
• Salting out is observed with high conc.
• 2-4% alcohol, glycerine, propylene glycol are used as dispersing agent
Advantages over tragacanth
• Available in several grades of standard viscosity
2. Sodium alginate :

69. 3. Pectin :
• Good gelling agent suitable for acidic products
• Used in many preparations including edible Jellies
• Glycerine is used as dispersing agent & humectant
• Pectin jelly is good medium for bacterial growth, add preservative
Storage:
Well closed container to prevent loss of moisture by evaporation

70. 4. Starch :
 Used in combination with other Jelling agent.
 Provides a water soluble dermatological base.
 Starch + Gelatin = Glycerin jelly product is still used
 Glycerin (up to 50%) may be added which acts as preservative
and humectant
Note:
• Must be freshly prepared
• Well closed container to prevent loss of moisture by evaporation

71. 5. Gelatin :
 Insoluble in cold water (swells and soften)
 Soluble in hot water
 2% gelatin forms jelly on cooling
 Stiff medicated Jellies can be prepared (15%)
 Melted before use and after cooling to desired temperature,
applied with a brush.
 Affected area covered with bandage and left in place for several
weeks
 Suitable preservative is required

72. 6. Cellulose derivatives :
 Produce neutral jellies of very stable viscosity
 Afford good resistance against microbial growth
 High clarity & produce a soft film after drying
Sodium CMC
• Used for preparation of lubricating & sterile jellies
• 1.5 - 5% - lubricant gels, 5% - Dermatological gels
• Withstand autoclaving temperature without deterioration
• Methyl cellulose – 3%

73. 7. Carbomer:
High molecular weight water soluble polymers of acrylic acid
which are crosslinked with allyl sucrose.
0.3-1% in lubricating gels & 0.5-5% as dermatological vehicle.
These have high gelling efficiency and used in low concentrations.
8. Poly vinyl alcohol (PVA):
PVA gels provide protection as they dry quickly to form a strong
residual film on skin.
These are available in various grades and viscosities.

74. Preparation of Gels:
1. Usually prepared by adding thickening agent along with
dispersing agent.
ex:Tragacanth,Carboxymethyl cellulose
2. Thickening agent is added to aqueous solution in which drug has
to be dissolved
3. Mass is triturated in a mortar until a smooth product is obtained
4. When coloured drug to be incorporated glass mortar is used
5. Whole gum is preferred to powdered gum to get clear
preparation of uniform consistency
6. Remaining ingredients are added with stirring.

75. Example:
Rx
Icthammol
Tragacanth
Alcohol (90%)
Glycerine
Water
-20g
-5g
-10g
-2g
-qs 100g
Send 100g Icthammol jelly
Procedure:
1. Tragacanth + alcohol motor mucilage.
2. Icthammol + glycerine + water Drug solution
3. Drug solution + mucilage triturate
4. Add water qs 100g
5. Transfer into container, label & dispense.

76. PACKAGING OF SEMISOLIDS:
The semisolid preparations are stored in a well closed amber
colored container to protect against Temperature and Light.
1. Ointment jars: Glass and porcelain
Plastic
2. Collapsible plastic tubes