1. Dr. Mehwish Qayyum
Pharm.d
Ms.Drug design and discovery (University of Surrey)
Senior lecturer
MAGMAS AND GELS

2. Gels
 Are semisolid systems consisting of either
suspensions made up of small inorganic
particles or large organic molecules in a liquid
vehicle rendered jelly like by the addition of a
GELLING AGENT.
 Sometimes called JELLIES

3.  High degree of physical/chemical cross
linking may be involved
 interlacing/ internal friction
 Resulting into high viscosity
 Responsible for semi-solid state

4. Terminologies related to gel
 Imbibition:
 Taking up of a certain amount of liquid without a
measureable increase in volume
 Swelling:
 Taking up of a liquid by gel with an increase in volume
 Syneresis
 Form of instability in which separation of solvent phase
occurs coz of elastic contraction of polymeric molecules
 Thixotropy
 A phenomenon in which if gel is agitated it may become
fluid and remain in solid state only after remaining
undisturbed for a period of time i.e sol gel transfer

5.  Examples of Gelling Agents
 1. Carbomers 910; 934; 934P; 940;
941;1342
 2. Carboxymethylcellulose; natural gums
 *0.5 to 2.0% concentration in water

6. Classes of Gel
 2 phase systems - separation between the insoluble matter and liquid
vehicle is observed. This type contains inorganic materials also small
particles distribute them in liquid in the form of
floccules(inorganic)(magma)
Example: Al(OH)3 Gel
 Single phase gel - consist of organic macromolecules uniformly
distributed throughout the liquid where no apparent boundary is
seen(organic)
Example: Na CMC and Tragacanth Gel(twisted mated strands wound
together by stronger vander waals forces to form crystalline and
amorphous regions)
 Continuous phase - commonly aqueous where alcohol and gels may be
use as continuous phase (organogels)
Example: Mineral oil + polyethylene resin = oleaginous ointment base
 Hydrogels
 Include ing that are dispersible as colloidals they include organic
hydrogels natural and synthetic gums e.g silica and methyle cellulose

7. Types of Gel
 Type 1-Heterogels
 Irreversible system
 3-dim structure
 Held by covalent bonds
 Show synerisis
 Type 2-Commonly used gels
 Heat reversible
 Held by h-bonds
 Gelling is influenced by pH additives
 Show synerisis

8.  Characteristics of Gels
 Gels may be thicken on standing, forming a
THIXOTROPE, and must be shaken before use
to liquefy the gel and enable pouring –
Aluminum Hydroxide Gel
 Because of high degree of attraction between
the dispersed phase and water medium, the gels
remain fairly uniform upon standing and does
not readily settle

9. Preparation of gels and
magmas:
Prpeared by freshly Desired gelatinous ppt
precipitating the dispersed results when solutions of
phase in order to achieve a inorganic agents react to
fine degree of subdivision of form an insoluble chemical
the particles and gelatinous having a high attraction for
character to those particles water.
As the microcrystalline
particles of ppt develop they
strongly attract water to
yield gelatinous particles
which for gel ppt

10. Preparation of gels and
magmas
Coz of high degree of attraction
Other magma and gels may be In addition to water vehicle
b/w disperse phase and the aq
prepared by +ion in water of other agents such as propylene
medium in both magmas and
inorganic chemical and hydrated glycol, hydroxy propyl cellulose
gels these prep remain fairly
form constitutes the dispersed etc may be used tto enhance gel
uniform on standing with little
phase of dispersion formation
settling of disperse phase
On long standind synerisis may Label should have statement
be seen but on little shaking shake well before use freezing
uniformity is re established must be avoided

11.  Preparation of Gels
1. By freshly precipitating the disperse phase upon
reacting an inorganic agents, a gelatinous
precipitate results
 Example: Preparation of Al(OH)3 gel is by
reacting Al(Cl)3 + Na2CO3
NaHCO3

12.  Preparation of Gels
2. By direct hydrating the inorganic material in
water
 Al2O3 + H2O Al(OH)3
 Examples: Aluminum Hydroxide Gel; Alugel;
Amphogel; Ce-lu-gel; Cremalin; Hydroxal;
Vanogel; Aluminum Phosphate Gel
(Phosphagel) - Antacid

13. Polyvinyl alcohols are used for gel preparation
in skin formulations when they are applied
these alcohol evaporate leaving a thin layer
on skin

14. Examples of Gel
 Clobetasol propionate- Termovate Gel
Dermatologic: Antipruritic

15. Example of Gel
 Acetic acid- Aci-jel
Vaginal: Restoration and maintenance of
acidity

16. Example of Gel
 Progesterone- Crinone Gel
Vaginal: Bioadhesive gel; Progesterone
supplement and replacement

17. Uses of gel
 Lubricant for catheters
 Bases for patch testing
 NaCl gel for electrocardiography
 Floucinonide Gel for anti- inflammatory
corticosteriod
 Na Fluoride & Phosphoric acid gel – dental
care prophylactic
 Tretionoin Gel for treatment of acne
 Prostaglandin Gel – intravaginal

18.  Gels and Magmas
 Are considered colloidal dispersion since they
contain particles of colloidal dimensions
 APPROPRIATE NAMES (COLLOIDAL DISPERSION)
 SOLS – term to designate a dispersion of solid in
either a liquid, solid or gas dispersion medium
 A. Prefix HYDRO – water as dispersion medium
so called HYDROSOL
 B. Prefix ALCO – alcohol as the dispersion
medium so called ALCOSOL
 C. AEROSOL – dispersion of solid or liquid in
gaseous phase

19. Examples Of Topical Gels
 1. Erythromycin and benzoyl peroxide topical
gel - Benzamycin
 2. Clindamycin Topical gel - Cleocin T Topical
Gel
 3. Benzoyl Peroxide Gel - Desquam-X 10 Gel -
acne vulgaris
 4. Hydroquinone Gel - Solaquin Forte Gel -
bleach for hyperpigmented skin
 5. Salicylic Acid Gel - Compound W Gel -
keratolytic
 6. Desoximetasone Gel - Topicort - anti-
Inflammatory, antipruritic agent

20.  Examples of Topical Gel
 Active Ingredient Proprietary Gelling agent Route and Use
1. Acetic acid Aci-jel Tragacanth, acacia Vaginal: restoration and
maintenance of acidity
2. Becaplermin Regranex Gel Na CMC Dermatologic
3. Benzoly peroxide Desquam-X Gel Carbomer 940 Acne vulgaris
4. Clindamycin Cleocin T Gel Carbomer 934P Acne vulgaris
5. Clobetasol Termovate Gel Carbomer 934 Antipruritic
6. Cyanocobalamin Nascobal Methylcellulose Nasal: hematologic
7. Desoximetasone Topicort Gel Carbomer 940 Anti-inflammatory;
antipruritic
8. Metronidazole Metro-Gel Carbomer 934P Vaginal-bacterial
9. Progesteron Crinone Gel Carbomer 934P Progesterone
supplement
10. Tretinoin Retin –A Hydroxypropyl Acne vulgaris
cellulose

21.  TRANSDERMAL PREPARATIONS
 Ointments, creams, gels designed to deliver a drug
systematically by addition of PENETRATION
ENHANCERS to the topical vehicle
 Examples of Penetration Enhancers
 Dimethyl sulfoxide (DMSO), ethanol, propylene
glycol, glycerin, polyethylene glycol, urea, dimethyl
acetamide, sodium lauryl
sulfate, poloxamers, Spans, Tweens, lecithin, and
terpenes
 Example: PLURONIC lecithin organogel (PLO) –
Pluronic (Poloxamer) F127 gel (usually 20% to 30%
concentration)