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International Journal of Universal Pharmacy and Bio Sciences 3(3): May-June 2014
INTERNATIONAL JOURNAL OF UNIVERSAL
PHARMACY AND BIO SCIENCES IMPACT FACTOR 1.89***
ICV 5.13*** Pharmaceutical Sciences REVIEW ARTICLE……!!!
NATURAL GELLING AGENTS: A REVIEW
Khushbu P.Shah1*, Dr Rashmi S. Srivastava
1, Ulhas G. Karle
2
1Mumbai Education Trust’s Institute of Pharmacy, Bandra (W), Mumbai, India.
2 Gayatri herbals Pvt .Ltd, Kalika towers, Kolbad road, Thane (W), Mumbai, India.
KEYWORDS:
Gelling agents,
Classification and
Properties, Screening of
Gelling agents.
For Correspondence:
Khushbu P.Shah*
Address:
M.PHARM Student,
Mumbai Education
Trust’s Institute of
Pharmacy,
MET Complex, Bandra
Reclamation,
Bandra (W), Mumbai
4000-50, India.
Email:
khushbushah590@gmail.
com
ABSTRACT
All pharmaceutical dosage forms contain many additives besides
the active ingredients to assist manufacturing and to obtain the
desired effect of the active ingredients. The advances in drug
delivery have simultaneously urged the excipients that are safe,
which directly or indirectly influence the rate and extent of release
and /or absorption of the drug. Today, the whole world is
increasingly interested in drugs and excipients of natural origin.
These excipients have advantages over synthetic ones since they
are more safe, biodegradable and available. This review discusses
about the majority of these gelling agents, their sources, chemical
constituents, and therapeutic uses as excipients in Pharmaceutical
drug delivery systems.
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INTRODUCTION
Gelling agent are hydrocolloidal substances that give thixotrophic consistency to the gel. These are
also known as solidifiers, stabilizer and thickening agents. They are widely used as excipients for
both conventional and novel dosage forms. Unfortunately the ‘Universal Gelling Agent’ doesn’t
exist yet. In recent years, there has been a tremendous development in natural products which are
needed to be used for a variety of purposes. The increasing interest in gelling agent of natural origin,
has led the pharmaceutical world to use most of them in the formulations. These excipients have
advantages over synthetic ones since they are safer, biodegradable and available .They can also be
modified in different ways to obtain tailor made materials for drug delivery systems and thus can
compete with the available synthetic excipients. Moreover, the tremendous orientation of pharma
world towards these naturally derived gelling agents has become a subject of increasing interest to
discover, extract and purify such compounds from the natural origin. Gelling agents of natural origin
are potent candidates that can be used in various pharmaceutical preparations and are one of the most
commonly used excipients for novel drug delivery system (NDDS). In this review, we have
described various natural gelling agents used in the pharmaceutical sciences. [1] [2] [4] [6]
NEED FOR NATURAL GELLING AGENT
a) Biodegradable – Naturally occurring polymers produced by all living organisms. They show
no adverse effects on the environment or human being.
b) Biocompatible and non-toxic – Chemically, nearly all of these plant materials are
carbohydrates in nature and composed of repeating monosaccharide units. Hence they are
non-toxic.
c) Safe and devoid of side effects – They are from a natural source and hence, safe and without
side effects.
d) Easy availability – In many countries, they are produced due to their application in many
industries. [1] [2] [3] [6]
The ideal Gelling agent has to meet a wide variety of specification.
It should posses properties such as thixotropic, non greasy, emollient and non-staining.
It should produce a reasonable solid-like nature during storage that can be easily broken
when subjected to shear forces generated by shaking the bottle, squeezing the tube, or during
topical application.
It should permit the incorporation of a large amount of drug.
It should not react, physically or chemically with the drug.
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Molecular weight, chemical functionality of gelling agent must allow diffusion and release of
the specific drug.
It should be easily manufactured and fabricated into the desired product and inexpensive.
It must be stable and must not decompose in the presence of drug and other excipients used
in the formulation, at high humidity conditions, or at body temperature.
Gelling agent and its degradation products must be nontoxic [1] [3] [4] [6]
Properties of Gelling Agent
1. Gelling agents are more soluble in cold water than hot water. Gelling agents like Acacia ,
Tragacanth have better solubility in cold water while Bentonite, Gelatin are more water
soluble in hot water
2. Gelling agents are used in concentration of 0.5 up to 10%
3. Gelling agents require a neutralizer or pH adjusting chemical to create the gel after the gelling
agent has been wetted in the dispersing medium
4. Most of these agents require 24-48 hours to completely hydrate and reach maximum viscosity
and clarity.
5. The viscosity of the gelling agents in the gelling layer is within range of about 1000 cps to
about 100,000 cps [2] [4] [5] [6]
Table No.1.Comparision of Gelling Agents Properties [10]
Gelling agent Compatibility Rheology Yield value Electrolyte stability
Aqueous Gelling Agents
Guar Gum
Cellulose Gum
Xanthan Gum
Hydorxy Ethyl Cellulose
Methycellulose
Carbomer
Acrylate Polmers
Polyetylene Glycol
Clay
Water
Water
Water
Water
Water
Water
Water
Water
Water
Thixotrophic
Pseudo plastic
Pseudo plastic
Pseudo plastic
Pseudo plastic
Pseudo plastic
Pseudo plastic
Newtonian
Thixotrophic
Yes
No
Yes
No
Yes
No
Yes
No
Yes
Yes
Yes
Yes
Yes
Yes
No
No
Yes
Yes
Non-Aqueous Gelling Agents
Polyethylenes
Trihydorxystearin (Organic)
Oragano Clays
Fumed Silisca
Oil
Oil
Oil
Oil
Oil
Pseudo plastic
Thixotrophic
Thixotrophic
Thixotrophic
Thixotrophic
Yes
Yes
Yes
Yes
Yes
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Disadvantages of Natural Gelling Agent
a) Microbial contamination – During production, they are exposed to external environment
and hence, there are chances of microbial contamination. However, this can be prevented by
proper handling and the use of preservatives
b) Batch to batch variation in formulation – Synthetic manufacturing is controlled procedure
with fixed quantities of ingredients while manufacturing of formulation using natural gelling
agent is dependent on environment and various physical factors.
c) The uncontrolled rate of hydration—Due to differences in the collection of natural
materials at different times, as well as differences in region, species, and climate conditions
the percentage of chemical constituents present in a given material may vary.
d) Slow Process – As the production rate is depends upon the environment and many other
factors, it can’t be changed. So natural gelling agent have a slow rate of production.
e) Incompatibility with Drug and Excipients – There are some Anionic gelling agents which
are incompatible with Cationic drug, preservatives or surfactant e.g. Sodium alginate
f) Heavy metal contamination – There are chances of Heavy metal contamination often
associated with herbal excipients. [1] [2] [5] [6] [8]
Few of the above mentioned disadvantages can be overcome by
Using proper techniques in processing of the gelling agents as per WHO guidelines
Detailed studies of physio-chemical incompatibility of such gelling agents with the
active pharmaceutical ingredients and other excipients in the formulation, use of
preservative and proper storage condition. [2][4]
Classification of Gelling Agents
A. Table no 2.CLASSIFICATION OF GELLING AGENTS ON THE BASIS OF
SOLUBILITY [1] [3] [4] [6]
PHARMACUTICAL GELLING AGENTS
AQUEOUS GELLING AGENTS
Cellulose and Its Derivatives
Gums
Clays
PEGS And Their Modifications
Synthetic Polymers
NON-AQUES GELLING AGENTS
Polyethylene’s
Organic
Organoclays
Silica’s
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B. Classification of Natural Gelling Agents On The Basis of Phyto-Chemical Occurance[1, 4-7, 10-20]
A. Table No 3. Classification of Gelling Agents (Polysacchrides Heteroglycans) [1] [4-7] [10-20]
GELLING AGENTS
PROTIENS
Gelatin
POLYSACCHARIDES/
HETEROGLYCAN
Acaia
Tragacanth
Locust bean gum
Guar gum
Pectin
Xanthan gum
Gellan gum
Chitosan
Agar
Sodium alginate
Carrageenan
MUCILAGE
Fenugreek Mucliage
Hibuscus Mucliage
Isabgul Mucilage
Aloe vera Mucilage (Gel)
MINERALS
Bentonite
Charge Source Chemical Nature Shape
Non-ionic seed
gums:
Guar, locust
bean,tamarind,xanth
an,galactomannans
.
Plant origin:
a) Shrubs/tree exudates -gum
arabica, gum ghatti,gum
karaya,gum tragacanth,
b) Seed gums-guar gum, locust
bean gum, starch, and amylase.
c) Extracts-pectin, larch gum.
d) Tuber and roots-potato,
starch.
Diheteroglycans:
Algins, carragennans,
galactomannans.
Branched:
Short branched :- guar
gum, locust bean gum
Marine/ Algal /Seaweed
Gums :-Alginates,
Carrageenans,Agar
Tri-heteroglycans:
Arabinoxylans, gellan,
xanthan.
Long branched :- karaya
gum, gum tragacanth, gum
Arabic
Anionic gums:
Arabic,karaya,
tragacant, gellan,
agar, algin,
carrageenans,
pectic acid.
Animal origin:-chitin and
chitosan, chondroitin sulfate,
hyaluronic acid.
Tetra-heteroglycans:
Gum arabic, psyllium seed
gum
Linear: amylase, pectin,
cellulose.
. Microbial origin:-Xanthan
Gum, Gellan gum
Penta-heteroglycans:
Ghatti gum, tragacanth.
Fragmented: gelatin,
collagen.
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1. GELATIN:-
Gelatin is a generic term for a mixture of purified protein fractions obtained either
by partial acid hydrolysis (type A) or by partial alkaline hydrolysis (type B) of
animal collagen. Gelatin may also be a mixture of both types.
Description:-
Appearance: - It appear as yellowish to slightly amber coloured, odourless and tasteless powder
Solubility: - Gelatin is practically insoluble in organic solvents, soluble in glycerine, acids and
bases. In water gelatin swells and softens gradually absorbing between 5 -10 times its own weight of
water. Gelatin is soluble in hot water, forming a gel on cooling to 35-40o C.
Chemical constituents: - The Gelatin protein fraction consists almost entirely of amino acid.
Therapeutically Gelatin is used in the preparation of wound dressing. Absorbable gelatin is
available as sterile film, ophthalmic film and sterile compressed sponge. Absorbable gelatin sponge
in Gel form is used as haemostatic during surgery [1] [5] [11-20]
2. ACACIA GUM:- (Gum Arabica, Indian Gum, Acacia)
The air dried gummy exudates from the stem and branches of Acacia senegal
Willd (Fam. Mimosoideae) and other species of African origin. It is also
known as Senegal gum.
Description:-
Appearance: - It appear as white or yellowish white thin flakes, odourless and mucilaginous in taste
Solubility: - The gum is freely soluble in equal weight of water to form a viscous and acidic
solution. Gum is insoluble in alcohol and other organic solvents.
Chemical constituents: - The chief chemical constituent is Arabian which is the mixture of
calcium, magnesium and potassium salts of Arabic acid
Therapeutically Acacia gum is used in the inflammation of intestinal mucosa. Due to its demulcent
properties it is used in various formulations of cough, diarrhoea and throat problems. It is also used
to cover inflamed surfaces such as burn. The gum is common ingredient in cosmetic formulations in
combination with tragacanth .The gum is use in concentration 10-15%. [1] [2] [5] [11-20]
3. TRAGACANTH GUM:- ( Tragacanth , Gum dragon)
Tragacanth is the air –dried gummy exudation obtained by incision from the
stems of Astragalus gummifer Labil. (White Gavan) or other Asiatic species of
Astragalus such as A. Kurdicus, A.adscendens and A.strobiliferus. (Fam.
Mimosoceae).
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Description:-
Appearance:- It appear as a white or yellowish white thin flakes, odourless and mucilaginous in
taste, it occurs as powdered form in various grades as per its qualities e.g. Ribbon 1-5 and Flakes 26-
28 ,55.
Solubility: - Practically insoluble in water, alcohol and other solvents. Although insoluble in water
tragacanth swells rapidly 10 times of its own weight of either cold or hot water
Chemical constituents: - The gum consists of a mixture of tragacanthin (water soluble portion) and
Bassorin (water insoluble polysaccharide). The insoluble portion swells to a gel and consists of 60-
70% of Basorrin
Therapeutically tragacanth is used in treatment of constipation it has demulcent and emollient
properties and is used in various cosmetic formulations like Hand lotions Tragacanth produce gel at
2-5% concentration which is acidic. It is stable at pH as low as 2. [1] [2] [4] [11-20]
4. Guar Gum:- (Cluster bean gum, Guar galactomannan , Jagur gum)
Guar Gum is seed gum produced from the powdered endosperm of the seeds of
Cyamopsis tetragaonolobus Linn, (Fam.Leguminoseae). The FDA has affirmed
guar gum as generally safe
Description;-
Appearance: - It appear as white or to yellowish-white powder, odourless and mucilaginous in taste
Solubility: - It is practically insoluble in organic solvents, in cold or hot water it disperses and swells
immediately to form a highly viscous and thixotrophic sol
Chemical constituents: - The water soluble fraction of Guar gum constitutes 85% of Guar gum and
is known as Guaran which is a galactomannan and protein is also present 5-7%.
Therapeutically, Guar gum has been used as bulk-forming laxative, appetite suppressant and in
peptic ulcer therapy. Guar gum is used in the treatment of Diabetes mellitus .Guar gum occurs as an
1% of guar gum is having same viscosity as to that of acacia, Guar gum has 5 to 8 times more
thickening power as compare to starch Guar gum is used as an ideal gelling agent in medicated tooth
paste, lotions, creams, and ointments. [1] [2] [3] [4] [5] [11-20]
5. LOCUST BEAN GUM:- ( Carob gum,Ceatonia)
The gum consists of the hydrocolloid from the powdered endosperm of the
seed of Ceratonia siliqua Linn. (Fam. Leguminosae), a tree native to the
Mediterranean region. Locust bean gum is a galactomannan and is similar to the guar gum.
Description:-
Appearance: - Gum appears as translucent white or yellow green in colour, odourless and
mucilaginous in taste
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Solubility: - The powdered gum swells in water to form a viscous mass, the viscosity is between 3-
11 cps and is insoluble in organic solvents.
Chemical constituents:-The Gum contains neutral polysaccharides 58% galactomannan, 29%
galactan and 3% petnosans. Protein and cellulose is also present
Therapeutically it is used as demulcent and adsorbent. In Food industry it is used as a substitute for
starch. [1] [2] [5] [11-20]
6. KARAYAGUM:- ( Sterculia, Indian tragacanth)
Sterculia is a dried gummy exudates of the tree Sterculia urens Roxb, S.villosa, S.
tomentosa, S.tragacantha (Fam. Sterculiaceae). It is the air-hardened product of the
viscous exudates from the trunk and branches of the plant.
Description:-
Appearance: - The best quality of Karaya gum is colourless; the lower grade shows a light pink to
very dark colour. The gum has a marked odour of vinegar and is mucilaginous in taste
Solubility: - The gum is insoluble in water but it swells considerably 60-100times in it.
Chemical constituents: - The gum consists of hetero-polysaccharides of sugar and uronic acids.
Therapeutically it is used as bulk laxative, denture adhesive in dental treatment [1] [5] [11-20]
7. GHATTI GUM :- ( Indian Gum, Ghati, Gutty)
Ghati gum is dried gummy exudates derived from the tree Anogeissus latifolea Roxb
(Fam. Combretaceae).
Description:-
Appearance: - The gum has light to dark brown colour, the light brown variety is the best, it is
odourless with mucilaginous taste.
Solubility: - The gum forms colourless viscous sol with water. A 5% solution in water has 50-400
cps viscosity
Chemical constituents: - The gum is calcium –magnesium salt similar to acacia.
The gum is edible hence it is given as a good tonic to woman after child birth [1] [2] [4] [5] [11-20]
8. POTATO STARCH:-
Starch consists of polysaccharide granules obtained from the tubers of Solanum
tuberosum Linn (Fam. Solanacae).
Description:-
Appearance: - It appears as slightly yellowish, odourless and mucilaginous in taste.
Solubility: - It is soluble in hot water at Gelatinisation range of 60 -70 0C allowing granules to swell,
this sol forms gel on cooling
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Chemical constituents: - Potato starch is fractionated into two structurally distinct polysaccharides
amylase (20%) and amylopectin (80%).
Therapeutically, starch is used as nutritive, demulcent, protective and as an absorbent. Starch gel is
used as an emollient skin and is also a base for enemas and suppositories .Antidote for iodine
poisoning [1] [2] [3] [11-20]
9. PECTIN:-
Pectin is the purified admixture of polysaccharide, obtained by carrying out the
hydrolysis in an acidic medium of the inner part of the rind of citrus peel, i.e.
Citrus limon or Citus auran tum (Fam. Rutaceae). Various sources of pectin are
listed in below table.
Table no.4: VARIOUS SOURCES OF PECTIN
Common name Botanical source Amount of pectin (%)
Lemon Citrus lemon 10-15
Orange Citrus aurantium 10-15
Apple Pyrus malus 10-12
Beets Beta Vulgaris 15-22
Papaya Carica papaya 9-12
Guava Psidium guyava 5-7
Sunflower heads Helianthus tuberosus 5
Appearance: - Pectin is a pale or cream coloured coarse or fine powder. It is odourless with
mucilaginous taste.
Solubility: - Pectin is insoluble in organic solvent but soluble in 20 parts of water. Different grades
of pectin are available based on it ‘Gelly- Grade’ is of 100,150 and 200 recommended for medicinal
and food usage. A 10 %( w/v) solution of pectin forms a gel on cooling, in acidic pH.
Chemical constituents: - Chemically, pectin is a neutral methoxy ester of pectic acid. Pectin is a
polyuronides and consists of mixture of pectic substances like protopectin, pectinic acid, and pectin
and calcium pectate. Gel strength depends on the degree of esertification. High methoxy pectin’s are
used in food industry; Low viscosity pectin’s have pharmaceutical applications.
Therapeutically, pectin is used as intestinal demulcent, treatment of indolent ulcers and deep
wounds, and a major component of anti-diarrhoeal formulation. It is used as haemostatic in cases of
haemorrhage. [1] [2] [6] [11-20]
10. SODIUM ALGINATE :- (Algin, Sodium poymannuronate)
Sodium alginate is the sodium salt of alginic acid, which is a purified
carbohydrate extracted from brown seaweed (algae) by the careful treatment with
sodium hydroxide.
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Description:-
Appearance: - It appears as yellowish white, cream or buff coloured, odourless and tasteless
powder.
Solubility: - Insoluble in organic solvents and strong acids, freely soluble in water. A 1% (w/v)
aqueous solution at 20oC may have a viscosity in the range of 20-400 cps.
Chemical constituents: - Alginic acid is a polyuronic acid composed of D- mannuronic acid and L-
glucouronic acid
Since Algin can absorb up to 300 times its own weight in water, therapeutically is used as lubricant and
moisturizer for body and skin care products[1] [2] [4] [11-20]
11. CARRAGEENAN
Carrageenan is a large polymer made up of galactose monomers. It is derived from
red seaweed (Rhodophyceae) found in the North Atlantic, mostly of genus
Chondrus crispus, Eucheuma cottonii and Eucheulma spinosum. Manufacture is by
hot water extraction under mild alkaline conditions followed by drying or precipitation. 0.5 -1 %
concentration is used for gel.
Appearance: - It appear as yellowish transparent, odourless, tasteless coarse or fine powder
Solubility: - Solubility in water depends on method of preparation, either hot or cold water. In order
to achieve good gels with reduced brittleness, increased solubility in water and intermediate freeze-
thaw stabilities, a blend of the three types is often used.
Chemical properties of different forms of carrageenan are depicted in below table 5.
Table no.5 : CHEMICAL PROPERTIES OF DIFFERENT FORMS OF
CARRAGEENAN
Properties Kappa Iota Lambda
Effect of
cations
Gels most strongly with
potassium ions
Gels most strongly with calcium
ions
Non-gelling
Type of gel Strong & brittle with
syneresis
Elastic & cohesive without
syneresis
Non-gelling
Water
solubility
Na salts are soluble in
hot or cold water, Ca &
K salts are soluble
above 60˚C
Na salts are soluble in hot or cold
water, Ca salts for a thixotropic
dispersion in cold water, K salts
are soluble above 60˚C
All salts are
soluble in hot
or cold water
Freeze-thaw
stability
Not stable Stable Stable
Chemical constituents: - Carrageenan contains a sulphate ester functional group and is capable of
forming helical structures with varying gelling properties. The three main types of carrageenan are
kappa, iota and lambda, each differing in the number of sulphate ester groups. The forms also differ
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in their gelling properties at room temperature. The use of carrageenan is limited by pH,
temperature, solubility and the presence of cations in the system.
Therapeutically, it is used as demulcent, emollient and Anti-Diarrhoeal .Carrageenan exhibits pseudo
plastic flow behaviour where increased shear rate decreases its viscosity but removal of the force
applied causes it to regain its initial viscosity[1] [2] [4] [5] [8] [11-20]
12. Xanthan gum :- (Corn Sugar Gum)
This gum is produced by a pure culture fermentation of carbohydrate with the
Xanthomonas Campestris and purified.
Description:-
Appearance: - It appear as cream coloured, odourless and free flowing powder
Solubility: - Soluble in cold and hot water giving highly viscous solution, which is stable towards
change in pH and also to heat. Viscosity is 1200-1600 cps for 1% w/v aqueous solution at 25oC.
Chemical constituent: - It is the sodium, potassium and calcium salt of D-glucose, D-mannose and
D-glucuronic acid, it also contains not less than 1.5% of pyruvic acid.
Xanthan gum exhibits a pseudoplastic flow behaviour which is directly proportional to the shear
rate. Aqueous solution is highly stable over a wide pH 4-10 range and temperature 10-60 o
C. [1] [2]
[7] [11-20]
13. Gellan gum:-
Gellan gum is an anionic, high molecular weight, deacetylated exocellular
polysaccharide gum produced as a fermentation product by a pure culture of
Sphingomonas elodea, the production organism is an aerobic, well
characterized, non-pathogenic, and gram-negative bacterium. Gellan gum acts
as a thickening or gelling agent and can produce textures in the final product
that vary from hard, non-elastic, brittle gels to fluid gels.
Descriptions:-
Appearance: - The gum appears as off-white powder, odourless and having bland taste. Gellan Gum
is available in a clarified form (KELCOGEL7) for foods and industrial products and a clarified form
of (GELRITE7) for microbiological media, plant tissue culture, and pharmaceutical applications.
Solubility: - Soluble in water, forming a viscous solution; insoluble in ethanol. It forms gels when
positively charged ions (i.e., cations) are added. Thus, the thickness and texture of gellan gum in
various products can be controlled by manipulating the addition of potassium, magnesium, calcium,
and/or sodium salts. In the same way, its melting temperature can be modified to either be below or
above 100° C
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Chemical constituents: - It has a tetrasaccharide repeat unit consisting of two glucose (Glc)
residues, one glucuronic acid (GlcA) residue, and one rhamnose (Rha) residue. These are linked
together to give a tetrasaccharide repeat unit. The native polysaccharide is partially esterified with L-
glycerate and acetate but the commercial product Gelrite®
has been completely de-esterified by
alkali Treatment.
Types of Gellan Gum:
It is available in two forms (high or low acyl content). The acyl groups have a profound influence on
gel characteristics.
The high acyl form produces soft very elastic and non-brittle gels, while the low acyl form produces
firm, non-elastic and brittle gels. They may be used alone or blended to give products with the
desired characteristics.
Gellan gum is one of the most interesting in situ gelling polymers that have been tested since it
seems to perform very well in humans. Gellan gum has high gel strength, an excellent stability,
process flexibility and tolerance, high clarity, excellent film former, low use level, thermally
reversible gel. [1] [2] [4] [5] [7] [11-20]
14. AGAR (Japanese Isinglass, Chinese, Isinglass or Vegetable Gelatin)
A polysaccharide complex extracted from the agarocyte of algae of the
Rhodophyaceae. Predominant agar-producing genera are Gelidium, Gracilaria,
Acanthopeltis, Ceramium, Pterocladia found in the Pacific and Indian Oceans.
Description:-
Appearance: - Agar appears as transparent, odourless, tasteless strips or coarse or fine powder.
Solubility: - It is insoluble in cold water .alcohol and slowly soluble in hot water to a viscid solution.
A 1% sol forms a stiff gel on cooling.
Chemical constituents: - Its chemical constituent can be separated into a neutral gelling fraction,
Agarose and a sulphated non –gelling fraction, Agaro-pectin
Therapeutically used as cathartic, in nutrient media for bacterial culture [1] [2] [4] [5] [6] [11-20]
15. CHITOSAN (Soluble Chitin)
Chitosan is a polysaccharide extracted from the shells of crustaceans, such as shrimp,
crab and other sea crustaceans, including Pandalus borealis and cell walls of fungi.
Description:-
Appearance: - chitosan appears as white coloured crystalline powder; it is odourless
and tastes less.
Solubility:- Chitosan is insoluble in water, organic solvents and aqueous bases and is soluble after
stirring in acids such as acetic, nitric, hydrochloric, perchloric and phosphoric acids Chitosan in
dilute acetic acid (1.25%0 has very high viscosity 120 cps.
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Chemical constituents: - It is a linear randomly distributed, hetero polysaccharide consisting of (1-
4) linked 2-acetamido-2-deoxy-D-glucopyranose and 2-amino-2-deoxy-Dglycopyranose units. It is
prepared by deacetylation of chitin.
Chitosan is considered one of the most valuable natural gelling agents for biomedical and
pharmaceutical applications due to its biodegradability, biocompatibility, antimicrobial, non-toxicity,
and anti-tumour properties. [1] [2] [5] [6] [11-20]
16. Fenugreek mucilage
Fenugreek, Trigonella Foenum-graceum, is an herbaceous plant of the (Fam.
Leguminoseae) Fenugreek seeds contain a high percentage of mucilage (a
natural gummy substance present in the coatings of many seeds).Mucilage is
extracted by multiple maceration of seeds.
Description:-
Appearance: - Mucilage appears as amorphous powder off white- cream yellow in colour with no
characteristic odour and tasteless
Solubility: - Mucilage although it does not dissolve in water, mucilage forms a viscous tacky mass
when exposed to fluids. Like other mucilage- containing substances, fenugreek seeds swell up and
forms viscous colloidal solution when they are exposed to fluids. Its swelling Index is 9. Its viscosity
(0.15 W/V Solution) is 1.4849 cps. . Gelling concentration lies between 2.5-3.5% w/v
Chemical constituents: - Mucilage contains polysaccharide galactomannan. The ripe seeds have
numerous applications in cosmetic and traditional medicine system of India.
Therapeutically, Mucilage is used as demulcent, emollient and tonic. [1] [2] [3] [5] [11-20]
17. Aloe Vera Mucilage:-
Aloe Vera mucilage is obtained after eliminating the outer most tissue of the
leaf of various species of Aloe such as Aloe berbadensis and Aloe vera
(Fam. Lilaceae).
Description:-
Appearance: - Aloe Vera mucilage appears as a clear gel with characteristic odour and bitter taste.
Aloe gel is often commercialised as powdered concentrate.
Solubility: - Aloe Vera dissolves slowly in water forming a viscous solution and is insoluble in
organic solvents
Chemical constituents: - The gel consists primarily of water (>98%) and polysaccharides.
Acemannan is considered the main functional component of aloe Vera and is composed of a long
chain of acetylated mannose. It also contains amino acids, vitamins, minerals and enzymes.
Important anthraquinones, emodin and aloin are also present.
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Traditionally, aloe Vera gel is used both, topically (treatment of wounds, minor burns, and skin
irritations) and internally to treat constipation, coughs, ulcers, diabetes, headaches, arthritis,
immune-system deficiencies. [1] [2] [5] [7] [8] [9] [11-20]
18. Isabgul mucilage:-
Psyllium seed mucilage, also known as ispaghula, isabgol, or simply as
psyllium, are portions of the seeds of the plant Plantago ovata, (Fam.
plantaginaceae), a native of India and Pakistan.
Appearance: - It appears as colourless fibrous material, which is odourless and has a bland taste.
Solubility: - They are soluble in water, forms a clear colourless mucilaginous gel by absorbing
water.
Chemical constituents:-Gel forming fraction of the alkali extractable polysaccharides is composed
of arabinose, xylose and traces of other sugars.
Therapeutically, used from the times of ayurveda as laxative to relive constipation. It also used for
the treatment of diarrhoea, crohns disease (inflammatory bowel ulcerative colitis disease), colon
cancer, obesity in children and adolescents high cholesterol and diabetes. [1] [2]
[5] [6] [9] [11-20]
19. Bentonite
A colloidal native hydrated aluminium silicate found in the mid west of the
U.S.A and Canada.
Appearance: - It appears as a cream to buff coloured fine powder, odourless and have an earthy
taste.
Solubility: - Bentonite is insoluble in water and organic solvents. It has the property of forming
highly viscous gel with not less than ten times its weight of water.
Chemical constituents: - Consist principally of montmorillonite, aluminium trioxide; silicone
dioxide .usually contains some magnesium iron the property of forming gel is increased by addition
of small amount of alkaline substances. [1] [2] [5] [11-20].
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TABLE NO.6 :- NATURAL GELLING AGENTS SCREENING
Sr .no Gelling Agent Appearance Viscosity Spreadabiltiy Stability
1. GELATIN + + + + +
2. ACAIA + + + + + + + +
3. TRAGACANTH + + + + + + + + +
4. GUAR GUM + + + + + + +
5. LOCUST BEAN
GUM
+ + + + + + + +
6. KARAYA GUM + + + + + + +
7. GHATI GUM + + + + +
8. POTATO STARCH + + + + +
9. PECTIN + + + + + + + + + + +
10. SODIUM
ALGINATE
+ + + + + + + + + + +
11. CARRAGEENAN + + + + + + + + + + +
12. XANTHAN GUM + + + + + + + + + + +
13. GELLAM GUM + + +
+ + + + + +
14. AGAR + + + + + + + +
15. CHITOSAN + + + + + + + + + + + +
16. FENUGREEK
MUCILAGE
+ + + + + + + + + + +
17. ALOE VERA
MUCILAGE
+ + + + + + + + + + + +
18. ISABGOL
MUCILAGE
+ + + + + ++ + + + +
19. BENTONITE + +
+ + +
+++ excellent , ++ very good & + good.
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TABLE NO .7 : NDDS APPLICATION OF GELLING AGENTS
Sr.no Name Of
Gelling
Agent
NDDS
Application
Pharmaceutical Research References
1. Gelatin Ophthalmic
films
A study was designed to investigate the potency of BHA-
GEL-GA-GEN pellet as gentamicin (GEN) delivery
system matrix which has been cross-linked with
glutaraldehyde (GA) 0.5%.
[1] [3] [21]
[22] [23]
2. Acaia Osmotic drug
delivery
Sustained release of ferrous sulphate was achieved for 7 h
by preparing gum Arabic pellets
[1] [3] [21]
[22] [24]
3. Tragacant
h
Sustained
Release Agent
Tragacanth when used as the carrier in the formulation of
1- and 3-layer matrices produced satisfactory release
prolongation either alone or in combination with other
polymers
[1] [3] [21]
[22] [25]
4. Guar Gum Colon-targeted
drug delivery,
cross-linked
microspheres
Guar gum, in the form of three-layer matrix tablets, is a
potential carrier in the design of oral controlled drug
delivery systems for highly water-soluble drugs such as
trimetazidine dihydrochloride.
[1] [3] [21]
[22] [26]
5. Locust
Bean Gum
Controlled
release agent
The gum was used to produce matrix tablets at different
concentrations (5% and 10%) by wet granulation method
using theophylline as a model drug
[1] [3] [21]
[22]
6. Karaya
Gum
Mucoadhesive
and
Buccoadhesive
It has been shown that mucoadhesive tablets prepared by
karaya gum for buccal delivery, had superior adhesive
properties as compared to guargum and was able to
provide zero-order drug release.
[1] [3] [21]
[22][27]
7. Ghati
Gum
Suspending
agent
Gum ghatti is used for development, evaluation and
optimization of sustained release mucoadhesive matrix
tablets of domperidon
[1] [3] [21]
[22] [27]
8. Potato
Starch
Gelling agent
and super
disintegrant for
Oro
Dispersible
tablets
Potato starch extract is used as an alternative serum
separator gel and its effects on glucose testing
[1] [3] [21]
[22]
9. Pectin Beads, floating
beads, colon
drug delivery,
micro
particulate
delivery,
transdermal
delivery,
Hydrogels
Recently pectin has been grafted with poly (N-
isopropylacrylamide) and studied as a potential carrier for
colon targeted drug delivery of theophylline
[1] [3] [21]
[23]
10. Sodium
Alginate
Bioadhvesive
microspheres,
nanoparticles,
microencapsula
tion
Bioadhesive sodium alginate microspheres of metoprolol
tartrate for intranasal systemic delivery were prepared to
avoid the first-pass effect, as an alternative therapy for
injection
[1] [3] [21]
[23]
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CONCLUSION:-
Natural Gelling agents play an important role in the Pharmaceutical drug delivery system. While
selecting gelling agents care should be taken regarding its toxicity and compatibility. This review,
gives an idea about the gelling agents of natural origin that can be potential substitute for the
synthetic gelling agents.
TABLE NO .7 : NDDS APPLICATION OF GELLING AGENTS Continue……….
Sr.No Name Of
Gelling
Agent
NDDS Application Pharmaceutical Research References
11. Carrageenan Hydrogel beads Hydrogel beads are prepared from a mixture of cross-
linked κ-carrageenan with potassium and cross-linked
alginate. These beads were introduced as novel carriers
for controlled drug delivery systems
[1] [3] [16]
[21] [23]
12. Xanthan
Gum
Bioadhvesive
microspheres,
nanoparticles,
microencapsulation
A controlled delivery system for propranolol
hydrochloride using the synergistic activity of LBG and
xanthan gum was studied
[1] [3] [21]
[23] [16]
13. Gellam
Gum
Ophthalmic drug
delivery,
Beads,hydrogels,
floating in-situ
gelling,controlled
release beads
The Nasal In-situ gel of gellan gum for Radix bupleri
was more efficacious
[1] [3] [21]
[22]
14. Agar Gel bead Formulation and evaluation of agar beads containing
phenobarbitone sodium was studied
[1] [3] [21]
[22] [27]
15. Chitosan Colon specific drug
delivery
,microspheres,
carrier for
protein as
nanoparticles.
Chitosan is a safe absorption enhancer which improve
mucosal (nasal, peroral) delivery of hydrophylic
macromolecules such as peptide and protein drugs and
heparins
[1] [3] [21]
[22] [15]
16. Fenugreek
Mucilage
Controlled Release
Agent
Mucilage derived from the seeds of fenugreek evaluated
as a matrix formulation containing propranolol
hydrochloride.
[1] [3] [21]
[22] [18]
17. Aloe Vera
Mucilage
Sustained Release
Agent
A controlled delivery system of glibenclamide using
aloe mucilage was studied
[1] [3] [21]
[23]
18. Isabgol
Mucilage
Hydrogels ,colon
drug delivery,
gastro-retentive
drug delivery.
A pH sensitive novel hydrogels using
N,N,methylenebisacrylamide as crosslinker and
ammonium persulfate (APS) as initiator for model drugs
(tetracycline insulin and tyrosine), for colon specific
drug delivery systems
[1] [3] [21]
[22]
19. Bentonite Opthalmic flims Controlled release of carbofuran from an alginate-
bentonite formulation. water release kinetics and soil
mobility.
[1] [3] [21]
[22]
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