BIODEGRADABLE POLYMERS USE IN CONTROLLED DRUG
DELIVERY
Hira Ijaz*1, Junaid Qureshi 1
1
College of Pharmacy, Govt. College University Faisalabad, Pakistan
Corresponding Author’s Phone: +92-3457808041, E-mail:pharmacisthira@gmail.com
*
Co-authors E-mail: junaid872009@hotmail.com
Abstract
All pharmaceutical dosage forms contain many additives besides the active ingredients to
assist manufacturing and to obtain the desired effect of the pharmaceutical active ingredients.
The advances in drug delivery have simultaneously urged the discovery of novel excipients
which are safe and fulfill specific functions and directly or indirectly influence the rate and
extent of release and /or absorption. The plant derived gums and mucilages comply with
many requirements of pharmaceutical excipients as they are non-toxic, stable, easily
available, associated with less regulatory issues as compared to their synthetic counterpart
and inexpensive; also these can be easily modified to meet the specific need. Most of these
plant derived gums and mucilages are hydrophilic and gel- forming in nature. Recent trend
towards the use of plant based and natural products demands the replacement of synthetic
additives with natural ones. Many plant derived natural materials are studied for use in novel
drug delivery systems, out of which polysaccharides, resins and tannins are most extensively
studied and used. This review discusses about the majority of these plant-derived polymeric
compounds, their sources, extraction procedure, chemical constituents, uses and some recent
investigations as excipients in novel drug delivery systems.
1. Introduction
Polymers are macromolecules having very large chains contain a variety of functional
groups, can be blended with low and high molecular weight materials. Polymers are
becoming increasingly important in the field of drug delivery. Advances in polymer science
have led to the development of several novel drug delivery systems. A proper consideration
of surface and bulk properties can aid in the designing of polymers for various drug delivery
applications (Omanathanu et al., 2011). Polymers have been successfully investigated and
1
employed in the formulation of solid, liquid and semi-solid dosage forms and are specifically
useful in the design of novel drug delivery systems. Both synthetic and natural polymers have
been investigated extensively for this purpose. Synthetic polymers are toxic, expensive, have
environment related issues, need long development time for synthesis and are freely available
in comparison to naturally available polymers (Varshosaz et al., 2006). Polymers are
becoming increasingly important in pharmaceutical applications especially in the field of
drug delivery. Polymers range from their use as binders in tablets to viscosity and flow
controlling agents in liquids, suspensions and emulsions; can also be used as film coatings,
1. To disguise the unpleasant taste of a drug,
2. To enhance drug stability and
3. To modify the release characteristics.
Around sixty million patients benefit from advanced drug delivery systems today, receiving
safer and more effective doses of medicines that are needed to fight a variety of human
ailments, including life threatening diseases. Examples of pharmaceutical polymers and the
principles of controlled drug delivery are outlined in this communiqué/report (Davis et al.,
1998; Henry et al., 2002).
Drug delivery is the method or process of administering pharmaceutical compound to achieve
a therapeutic effect in humans or animals. Drug delivery technologies modify drug release
profile, absorption, distribution and elimination for the benefit of improving product efficacy,
safety, as well as patient compliance and convenience.
Biodegradable polymers can be defined as polymers that are degradable in vivo, either
enzymatically or nonenzymatically, to produce biocompatible or nontoxic by-products. These
polymers can be metabolized and excreted via normal physiological pathways. They are
classified into three groups, namely natural, semi synthetic, and synthetic, based on their
sources. Examples of commonly used natural biodegradable polymers are gelatin, alginate,
Biodegradable polymers are a newly emerging field. A vast number of biodegradable
polymers have been synthesized recently and some microorganisms and enzymes capable of
degrading them have been identified. In developing countries, environmental pollution by
synthetic polymers has assumed dangerous proportions. As a result, attempts have been made
to solve these problems by including biodegradability into polymers in everyday use through
slight modifications of their structures. Biodegradation is a natural process by which organic
chemicals in the environment are converted to simpler compounds, mineralized and
redistributed through elemental cycles such as the carbon, nitrogen and sulphur cycles.
2
The first disclosure of the use of a synthetic biodegradable polymer for the systemic delivery
of a therapeutic agent was made in 1970 by Yolles and Sartori. Since that time, a substantial
body of literature on drug release from bioerodible polymers has been generated as attention
turned to custom- synthesized biodegradable polymers.
Three basic approaches have been evolved:
(1) Erosion of the polymer surface with concomitant release of physically entrapped drug;
(2) Cleavage of covalent bonds between the polymer and drug, occurring in the polymer bulk
or at the surface, followed by drug diffusion
(3) Diffusion-controlled release of the physically entrapped drug, with bio-absorption of the
polymer delayed until after drug depletion (Joshi et al., 2012).
A range of materials have been employed to control the release of drugs and other active
agents. The earliest of these polymers were originally intended for other, non-biological uses,
and were selected because of their desirable physical properties, for example:

Poly (urethanes) : For elasticity and coatings

Poly (siloxanes) : Silicones for insulating ability

Poly (methyl methacrylate): For physical strength and transparency. It has a good
degree of compatibility with human tissue and can be used to create microfluidiclabon-achip devices.

Poly (vinyl alcohol): For hydrophilicity and strength. Used for Feminine hygiene and
adult incontinence products as a biodegradable plastic backing sheet.

Poly (vinyl pyrrolidone): For suspension capabilities. Mostly used as adhesives
(Sharma et al., 2011).
Some of the materials that are currently being used or studied for controlled drug delivery
include;

Poly(2-hydroxy ethyl methacrylate).

Poly(N-vinyl pyrrolidone).

Poly(methyl methacrylate).

Poly(vinyl alcohol).

Poly(acrylic acid).

Polyacrylamide.

Poly(ethylene-co-vinyl acetate).

Poly(ethylene glycol)

Poly(methacrylic acid).
3
Many of these materials are designed to degrade within the body, among them are;

Polylactides (PLA).

Polyglycolides (PGA).

Poly(lactide-co-glycolides) (PLGA).

Polyanhydrides.

Polyorthoesters.
1.1 Controlled-Release Mechanisms
Controlled drug delivery or modified release delivery systems may be defined as follows -:
The controlled release system is to deliver a constant supply of the active ingredient, usually
at a zero-order rate, by continuously releasing, for a certain period of time, an amount of the
drug equivalent to the eliminated by the body. An ideal Controlled drug delivery system is
the one, which delivers the drugs at a predetermined rate, locally or systematically, for a
specific period of time (Ummadi et al., 2013).
Controlled-release methodologies can be classified on the basis of the mechanism that
controls the release of the active agent from the delivery system: polymer erosion, diffusion,
swelling followed by diffusion or degradation. Any of these mechanisms may occur in
a given release system.
1.1.1 Polymer erosion:
The choice of a particular erosion mechanism is dictated by the specific application. The
various polymer erosion mechanisms are of 3 basic types;
Type I erosion
Type II erosion
Type III erosion
1.1.1.1 Type I erosion
Type I erosion involves hydrolysis of hydrogels and these are useful in the controlled release
of macromolecules entangled within their network structure.
1.1.1.2 Type II erosion
Type II erosion involves solubilization of water-insoluble polymers by reactions involving
groups pendant from the polymer backbone. Of particular interest are polymers that
solubilize by ionization of carboxylic acid groups, and the utilization of those systems is
described.
1.1.1.3 Type III erosion
Type III erosion involves cleavage of hydrolytically labile bonds within the polymer
4
backbone and four distinct polymer systems within this category are under development.
One system involves the diffusion of drugs from a reservoir through a bioerodible membrane,
another system utilizes microcapsules, a third system utilizes monolithic devices, and the
fourth system utilizes drugs chemically bound to a bioerodible polymer (Sharma et al., 2011).
1.1.2 Diffusion
Diffusion occurs when a drug or other active agent passes through the polymer that forms
the controlled-release device (Khullar et al., 1999).
The diffusion can occur on a macroscopic scale as through pores in the polymer matrix or on
a molecular level, by passing between polymer chains. For the diffusion-controlled systems,
the drug delivery device is fundamentally stable in the biological environment and does not
change its size either through swelling or degradation. In these systems, the combinations of
polymer matrices and bioactive agents chosen must allow for the drug to diffuse through the
pores or macromolecular structure of the polymer upon introduction of the delivery system
into the biological environment without inducing any change in the polymer itself (Nokanom
et al., 2006).
1.1.3 Swelling-controlled release systems
They are initially dry and, when placed in the body will absorb water or other body fluids and
swell. The swelling increases the aqueous solvent content within the formulation as well as
the polymer mesh size, enabling the drug to diffuse through the swollen network into the
external environment. Most of the materials used in swelling-controlled release systems are
based on hydrogels, which are polymers that will swell without dissolving when placed in
water or other biological fluids. These hydrogels can absorb a great deal of fluid and, at
equilibrium, typically comprise 60–90% fluid and only 10–30% polymer. One of the most
remarkable, and useful, features of a polymer's swelling ability manifests itself when that
swelling can be triggered by a change in the environment surrounding the delivery system.
Depending upon the polymer, the environmental change can involve pH, temperature, or
ionic strength, and the system can either shrink or swell upon a change in any of these
environmental factors. As many of the potentially most useful pH-sensitive polymers swell at
high pH values and collapse at low pH values, the triggered drug delivery occurs upon an
increase in the pH of the environment (Andreopoulos et al., 2001).
1.1.4 Degradation
Biodegradable polymer degrades within the body as a result of natural biological processes,
eliminating the need to remove a drug delivery system after release of the active agent has
5
been completed. Most biodegradable polymers are designed to degrade as a result of
hydrolysis of the polymer chains into biologically acceptable, and progressively smaller,
compounds (Poddar et al., 2010). Degradation may take place through bulk hydrolysis, in
which the polymer degrades in a fairly uniform manner throughout the matrix. For some
degradable polymers, most notably the poly-anhydrides and poly ortho-esters, the
degradation occurs only at the surface of the polymer, resulting in a release rate that is
proportional to the surface area of the drug delivery system. Once the active agent has been
released into the external environment, one might assume that any structural control over
drug delivery has been relinquished. However, this is not always the case. For transdermal
drug delivery, the penetration of the drug through the skin constitutes an additional series of
diffusional and active transport steps.
1.2 Biodegradability of Polymers
Biodegradable plastics normally refer to an attack by microorganisms on non water soluble
polymer-based materials (plastics). This implies that the biodegradation of plastics is usually
a heterogeneous process. Because of a lack of water solubility and the size of the polymer
molecules, microorganisms are unable to transport the polymeric material directly into the
cells where most biochemical processes take place; rather, they must first excrete
extracellular enzymes which de-polymerize the polymers outside the cells (Sharma et al.,
2011). Drug-polymer linkages should be designed to be hydrolysed by lysosomal enzymes,
being resistant to attack in other body compartments. There are many enzymes in lysosomes,
including proteases, nucleases and glycosidases. The extent of the active sites of enzymes and
the number of interactions that participate in the formation of an enzyme-substrate complex
require that an artificial substrate should contain features of the degradable sequences of the
physiological substrates. Thus, to introduce degradable bonds into carbon chain polymers, it
is necessary to combine them with peptide, saccharide, or nucleotide sequences. From these
possibilities, we have chosen oligopeptide side chains as suitable attachment/release sites.
Using this type of side chains, both their length, and structure” can be altered by changing the
sequences of amino acid residues (Kopeček et al., 1984).
2. POLYMERS IN PHARMACEUTICAL APPLICATIONS
2.1 POLYSSACHARIDES:
2.1.1 Tamarind gum
Tamarind gum contains xylo-glycon present in tamarind seed. It is a hydrophilic polymer and
had been limited for use as gelling thickening, suspending and emulsifying agents (Rao et al.,
1973; Nandi et al., 1975). It possesses properties like high viscosity, broad pH tolerance and
6
adhesivity (Rao et al., 1946; Kulkarni et al., 1997). In addition to these other important
properties of TSP have been mucoadhesivity, biocompatibility, high drug holding capacity
and identified recently. They include non- carcinogenicity high thermal stability (Burgalassi
et al.,1996; Indian Pharmacopoeia. 1996; Sano et al., 1996; Sujja et al., 1996). This led to its
application as excipient in hydrophilic drug delivery system. High patient compliance and
flexibility in developing dosage forms made the oral drug delivery systems the most
convenient mode of drug administration compared to other dosage forms. Of these, matrix
systems have gained widespread importance.
2.1.2 Okra gum:
Okra gum, obtained from the fruits of Hibiscus esculentus, is a polysaccharide consisting of
D-galactose, L-rhamnose (Agarwal et al., 2001: Tavakoli et al., 2004) and
L-galacturonicacid. Okra gum is used as a binder. In a study, okra gum has been evaluated as
a binder in paracetamol tablet formulations (Emeje et al., 2007). These formulations
containing okra gum as a binder showed a faster onset and higher amount of plastic
deformation than those containing gelatin. The crushing strength and disintegration times of
the tablets increased with increased binder concentration while their friability decreased.
Although gelatin produced tablets with higher crushing strength, okra gum produced tablets
with longer disintegration times than those containing gelatin. It was finally concluded from
the results that okra gum maybe a useful hydrophilic matrixing agent in sustained drug
delivery devices. In another study Okra gum was evaluated as a controlled release agent in
modified release matrices, in comparison with sodium carboxymethyl cellulose (NaCMC)
and hydroxypropylmethyl cellulose (HPMC), using paracetamol as a model drug. Okra gum
matrices provided controlled release of paracetamol for more than 6hr and the release rates
followed time-independent kinetics. The release rates were dependent on the concentration of
the drug present in the matrix. Okra gum compared favourably with NaCMC, and a
combination of Okra gum and NaCMC, or on further addition of HPMC resulted in near zero
order release of paracetamol from the matrix tablet. The results indicate that Okra gum
matrices could be useful in the formulation of sustained release tablets for up to 6hr.
2.1.3 Guar gum
Guar gum is one of the outstanding representatives of that new generation of plant gums. Its
source is an annual pod-bearing, drought -resistant plant, called Guar, or cluster bean
(Cyamopsistetragonolobus or C. psoraloides), belonging to the family Leguminosae. It has
been grown for several thousand years in India and Pakistan as a vegetable, and a forage
crop.
7
After having been removed from their pods the spherical, brownish seeds the size of a small
pea, are passed rapidly through a flame and thus loosened; hard seed hulls are then removed
in a scouring or "pearling operation (Chudzikowski, et al., 1971). Various grades are
available depending on colour (white to greyish), mesh size, viscosity
2.1.4Locust bean gum:
Locust bean gum from Ceratonia sifiquu has a mannose to galactose ratio of about 3.5-4.0
while this ratio for guar gum, from Cyamopsistetragonolobus, is about 1.8-2.0. It is known
that the galactose substituents are clustered mainly in doublets approximately randomly
spaced, the ‘hairy regions’, interspersed by longer regions of unsubstituted mannan backbone,
the ‘smooth regions’. These two types of galacto-mannans are employed by the food industry
as thickeners but they are generally considered not to form gels on their own although LBG
does at high concentrations under specific conditions, i.e. at low temperature or upon ageing.
The Xanthomonascampestris extracellular polysaccharide (xanthan gum), which has found
widespread technological application and has a cellulose backbone substituted on every
second residue with a charged tri-saccharide side chain. This side chain consists of two
mannose units separated by a glucuronic acid residue. The mannose residue attached to the
cellulosic backbone is variably acetylated and the terminal mannose can contain a pyruvate
group. Xanthan gum, which in itself is non-gelling, undergoes a temperature-induced
conformational transition from an ordered helical structure to a disordered one. This
transition temperature is strongly dependent on the salt content (Schorsch et al., 1997).
2.1.5 Psyllium seed husk
Psyllium seed husk (PSH) has a long and established record as a bowel regulator. More
recently, it has been demonstrated to lower blood cholesterol levels.
These physiological properties have been thought to be due to the extraordinary gel-forming
characteristics of this material. Over 50 years ago Laidlaw & Percival (1950) studied the
chemical features of some fractions of the whole seed, and in the late 1970s reported some
structural features of the carbohydrate extracted from the husk (Marlett et al., 2003).
Dietary fibers from psyllium have been used extensively both as pharmacological
supplements, food ingredients, in processed food to aid weight control, to regulation of
glucose control for diabetic patients and reducing serum lipid levels in hyperlipidemics.
Therapeutic value of psyllium is for the treatment of constipation, diarrhea, irritable bowel
syndrome, inflammatory bowel disease-ulcerative colitis, colon cancer, diabetes and
8
hypercholesterolemia and exploitation of psyllium for developing drug delivery systems
(Singh et al., 2007).
2.1.6 Sterculiafoetida:
Sterculia is a genus colloquially termed as tropical chestnuts (Sterculiafoetida). It contains a
mixture of D-galactose, L-rhamnose and D-galactouronic acid. The galctouronic acid
48 units are the branching points of the molecule. In an independent investigation Sterculia
foetida gum as a hydrophilic matrix polymer for controlled release preparation was evaluated.
Different formulation aspects considered were: gum concentration (10–40%), particle size
(75–420μm) and type of fillers. Tablets prepared with Sterculiafoetida gum were compared
with tablets prepared with Hydroxymethyl cellulose K15M. The release rate profiles were
evaluated through different kinetic equations: zero-order, first-order, Higuchi, Hixon-Crowell
and Korsemeyer Peppas models. Suitable matrix release profile was obtained at 40% gum
concentration. Higher sustained release profiles were obtained for Sterculiafoetida gum
particles in size range (Avachat, et al., 2011).
2.1.7 Honey locust gum:
Honey locust gum (HLG) obtained from Gleditsiatriacanthos (honey locust) beans (Üner et
al., 2004). Honey locust gum (HLG) was used to produce matrix tablets at different
concentrations (5% and 10%) by wet granulation method. Theophylline was chosen as a
model drug. The matrix tablets containing hydroxyethylcellulose and hydroxypropyl
methylcellulose as sustaining polymers at the same concentrations were prepared and a
commercial sustained release (CSR) tablet containing 200mg theophylline was examined for
HLG performance. No significant difference in in-vitro studies was found between
CSR tablet and the matrix tablet containing 10% HLG (Avachat, et al., 2011).
2.1.8 Tara gum
Tara gum is obtained from the endosperm of seed of Caesalpiniaspinosa, commonly known
as tara. It is small tree of the family Leguminosaeor Fabaceae. Tara gum is a white, nearly
odorless powder. It is produced by separating and grinding the endosperm of the mature
black color seeds .Tara gum is a potential replacement for locust bean gum for use as a
formulation aid, stabilizer, and thickener for food applications (Borzelleca, et al.,1993).
2.1.9 Aloe mucilage
The inner part of the leaves of Aloe vera (L.) Burm.f. (Aloe barbadensis Miller) contains
many compounds with diverse structures have been isolated from both the central
9
parenchyma tissue of Aloe vera leaves and the exudates arising from the cells adjacent to the
vascular bundles. The bitter yellow exudates contains 1, 8 dihydroxy anthraquinone
derivatives and their glycosides (Jani et al., 2008; Ross et al., 1999). The aloe parenchyma
tissue or pulp has been shown to contain proteins, lipids, amino acids, vitamins, enzymes,
inorganic compounds and small organic compounds in addition to the different
carbohydrates. Many investigators have identified partially acetylated mannan (or
acemannan) as the primary polysaccharide of the gel, while others found pectic substance as
the primary polysaccharide. Other polysaccharides such as arabinan, arabinorhamnogalactan,
galactan,
galacto-galacturan,
glucogalacto-mannan,
galacto-glucoarabinomannan
and
glucuronic acid containing polysaccharides have been isolated from the Aloe vera inner leaf
gel part (Malviya, et al., 2011).
2.1.10 Hakea gum:
Hakea gum a dried exudate from the plant Hakea gibbosa family Proteaceae. Gum exudates
from species have been shown to consist of L-arabinose and D-galactose linked as in gums
that are acidic arabino-galactans (type A). Molar proportions (%) of sugar
Constituents Glucuronic acid, Galactose, Arabinose, Mannose, Xylose is 12:43:32:5:8.
The exuded gum is only partly soluble in wate. Hakea gibbosa (Hakea) was investigated as a
sustained release and mucoadhesive component in buccal tablets. Tablet with drug
chlorpheniramine maleate (CPM) with either sodium bicarbonate or tartaric acid in a 1:1.5
molar ratio and different amount of Hakea were formulated using a direct compression
technique and were coated with hydrogenated castor oil (Cutina) on all but one face. The
resulting plasma CPM concentration versus time profiles was determined following buccal
application of the tablets in rabbits (James et al., 1993; Kokate et al., 2003).
2.1.11 Konjacglucomannan:
Konjacglucomannan, which is extracted from the tubers of Amorphophalluskonjacis a very
promising
polysaccharide
for
incorporation
into
drug
delivery
systems.
The
konjacglucomannan molecule consists of D-glucose and Dmannose linked by 13-14 linkage,
and the ratio of mannose to glucose has been reported as 1.6:1, while there is some branching
at the C-3 of the mannose unit . Since konjacglucomannan by itself forms very weak gels, it
has been investigated as an effective excipient in controlled release drug delivery devices in
combination with other polymers or by modifying its chemical structure.Matrix tablets
prepared from konjacglucomannan alone showed the ability to sustain the release of
cimetidine in the physiological environments of the stomach and small intestines but the
presence of mannanase (colon) accelerated the drug release substantially. Mixtures of
10
konjacglucomannan and xanthan gum in matrix type tablets showed high potential to sustain
and control the release of the drug due to stabilization of the gel phase of the tablets by a
network of intermolecular hydrogen bonds between the two polymers to effectively.
2.1.12MIMOSA PUDICA MUCILAGE
Mimosa pudica (family Mimosaceae), commonly known as sensitive plant, is a diffuse
Under shrub found widely in the tropical and subtropical parts of India. Seeds of
pudica yield mucilage, which is composed of d-xylose and d-glucuronic acid. Mimosa
seed mucilage hydrates and swells rapidly on coming in contact with water. During
earlier study in our laboratory, the disintegrating and binding properties of Mimosa seed
mucilage were evaluated. In the present work, we have isolated and characterize
Mimosa seed mucilage and evaluated its sustained-release properties employing
diclofenac sodium (DS) as a model drug. The matrix tablet of DS was formulated using
,wet granulation method and evaluated for appearance, weight variation, hardness
friability, in vitro drug release, swelling, and erosion behavior (Malviya, et al., 2011).
2.1.13 Hupu gum
Hupu gum or Gum kondagogu (GKG) is a naturally occurring polysaccharide derived as an
exudate from the tree (Cochlospermumgossypium). Basically it is a polymer of rhamnose,
galacturonic acid, glucuronic acid, b-D galactopyranose, a-D-glucose, b-D-glucose,
galactose, arabinose, mannose and fructose with sugar linkage. Hupu gum is also composed
of higher uronic acid content, protein, tannin and soluble fibers (Janaki et al., 2000).
2.1.14 Albizia gum
Albizia gum is obtained from the incised trunk of the tree Albiziazygia, family
Leguminosaeand is shaped like round elongated tears of variable color ranging from yellow
to dark brown. It consists of 1– 3-linked D-galactose units with some ß1-6-linked D-galactose
units. The genus Albizzia containing some twenty-six species is a member of the
Mimosaceae, a family which also includes the gum-bearinggenera Acacia and Prosopis. Only
two species of Albizia, A.zygia and A. sassa, are however known to produce gum. Albizia
gum has been investigated as a possible substitute for gum arabic as a natural emulsifier for
food (Ashton et al., 1975).
2.1.15 FENUGREEK mucilage
Trigonella Foenum-graceum, commonly known as Fenugreek, is an herbaceous plant of the
leguminous family. Fenugreek seeds contain a high percentage of mucilage (a natural gummy
11
substance present in the coatings of many seeds). 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 become slick when they are exposed to fluids
(Fulzele et al., 2003). The husk from the seeds is isolated by first reducing the size, and then
separated by suspending the size reduced seeds in chloroform for some time and then
decanting. Successive extraction with chloroform removes the oily portion which is then air
dried (Henry et al., 2002). A different extraction procedure is also reported to isolate the
mucilage from the husk. The powdered seeds are extracted with hexane then boiled in
ethanol. The treated powder is then soaked in water and mechanically stirred and filtered.
Filtrate is then centrifuged, concentrated in vacuum and mixed with 96% ethanol. This is then
stored in refrigerator for 4 hrs to precipitate the mucilage (Petropoulos et al., 2002)
2.1.16 Lepidiumsativum:
In a different study a gel forming husk powder obtained from Lepidiumsativum seeds was
used to prepare solid controlled release oral unit dose pharmaceutical composition,
comprising one or more of therapeutic agent/drug. The gel forming husk powder obtained
from Lepidiumstivum seeds are present in the range of 10 to 70 % of the total weight of
dosage form, the cross-linking enhancer selected from xanthan gum, karaya gum and the like
in amounts of between 3 to 10 % by weight of the dosage form to give a release profile
between 4 to 20 hours. The total excipients present are between 10 to 40 % by weight of the
total dosage form (Avachat et al., 2002).
2.1.17 Gum copal (GC)
Gum
copal
(GC)
is
a
natural
resinous
material
of
plant Burserabipinnata (family Burseraceae). It has been used as a raw material for varnish
because it produces glossy films with good weather protection properties. It has been used as
pigment binder in varnishes due to the excellent binding properties. It has been mainly used
as an emulsifier and stabilizer for the production of colour, paints, printing inks, aromatic
emulsions and meat preservatives. Interestingly, GC was also used as medicine for several
different ailments such as in the treatment of burns, headache, nose bleed, fever,
stomachache, and in the preparation of dental products and as remedy for loose teeth and
dysentery (Morkhade et al., 2006).
2.1.18 Gum damar (GD)
Gum
damar
(GD)
is
a
whitish
to
yellowish
natural
gum
of
plant ShoreaWiesneri (family Dipterocarpaceae). It contains about 40% alpha-resin (resin
that dissolves in alcohol), 22% beta resin, 23% dammarol acid and 2.5% water. It has been
12
mainly used as an emulsifier and stabilizer for the production of colour, paints, inks and
aromatic emulsions in food and cosmetic industries and also in the manufacture of paper,
wood, varnishes, lacquers, polishes and additives for beverages. It has been used for waterresistant coating and in pharmaceutical and dental industries for its strong binding properties.
In India, Sal damar has been widely utilized as an indigenous system of medicine. These
wide applications of GC and GD propose their strong hydrophobic nature, substantial binding
property and compatibility with the physiologic environment. Since matrix tablet is the
easiest approach to design the sustained drug delivery system, we were interested in
investigating the matrix-forming ability of GC and GD in tablets for sustained drug delivery
(Morkhade et al., 2006).
3 TANNINS
3.1 Bhara Gum
The gum obtained from Terminaliabellerica was investigated for its application as a release
rate retarding polymer. The natural materials have been extensively used in the field of drug
delivery for their easy availability, cost effectiveness ,eco-friendliness, capable of multitude
of chemical modifications, potentially degradable and compatible due to natural origin
(Shankar et al., 2008).
4 OTHERS:
4.1 Moi gum
The gum is obtained from Lanneacoromandelica (Houtt.) Merrill (Anacardiaceae). Moigum
is yellowish white color in fresh and on drying becomes dark. Gum ducts are present in
leaves, stems and fruits and are most abundant in the bark of the stem. Natural gum moi was
successfully evaluated as microencapsulating agent and release rate controlling material for
lamivudine. Microspheres were prepared by solvent evaporation technique. Effect of drug:
gum ratio on in vitro drug release profile was investigated. The rate limiting capacity of moi
gum was compared with guar gum as control by keeping all the parameters constant. The
gum produced microspheres having satisfactory size (24-32μm) and acceptable
morphological properties. Gum exhibited sustained action beyond 10 hr in comparison to
guar gum but the combination of both the gums in 1:1 ratio demonstrated an additional
sustained action (Avachat et al., 2011).
5 Conclusion
The use of natural gums for pharmaceutical applications is attractive because they are
economical, readily available, non-toxic, capable of chemical modifications, potentially
13
biodegradable and with few exceptions, also biocompatible. Natural gums can also be
modified to have tailor-made products for drug delivery systems and thus can compete with
the synthetic controlled release excipients available in the market. Though the use of
traditional gums has continued, newer gums have been used, some of them with exceptional
qualities.
6 ACKNOWLEDGEMENT
All praises and thanks are for the Almighty ALLAH, who is merciful, benevolent
and whose bounteous blessings enabled me to make a small contribution to the existing ocean
of computer knowledge. After the Almighty ALLAH, all praises and thanks are for the Holy
Prophet MUHAMMAD (Sallala Ho ElaheyWasallam) who is forever a model of guidance
and knowledge for humanity. I feel highly privileged to express my heartiest and ineffable
gratitude to my sincere and honorable teachers, for dynamic supervision, constructive
guidance and affectionate behavior throughout my studies. Special thanks for their guidance
would always be due.
Fig:1 Structure of Guar Gum
14
Fig:2 Structure of Locous Been Gum
Fig:2 Structure of Hupu Gum
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