Guar gum: A Potential Natural Hydrophilic Polymer
Pankaj S. Waghere1*, Malpani Amol2,
1Prin. K. M. Kundnani College of Pharmacy, Mumbai. Maharashtra, India.
2Roland Institute of Pharmaceutical Sciences, Berhampur. Orissa, India.
Hydrocolloids are naturally-occurring plant polysaccharide, in that gaur gum is most useful and validated natural plant polysaccharide. Guar gum and their derivatives are widely used in pharmaceutical dosage forms. Many are used as biodegradable polymeric materials to deliver active pharmaceutical ingredients. Natural polymers can be modified to obtain tailor-made materials for drug delivery systems and to compete with the synthetic biodegradable excipients available in the market. Natural polymers as a drug carrier material are of two types: polysaccharides and proteins. They found both in plants and animals providing several advantages over synthetic polymers.Gaur gums are preferred to those of synthetic origin due to their green, cost-effectiveness, nontoxic, easy availability and for suitable binder in tablet manufacture. The aim of this review is to provide an insight into the many potential applications of gaur gum as pharmaceutical natural excipients.
Reference Id: PHARMATUTOR-ART-1359
Natural polymers are defined as polymeric materials derived from plant exudates. In thousands of years back, most useful material in nature is natural polymer in various purpose for medicinal application but now a day new approach is the hydrophilic polymers as a plant source and they are derived in to three groups-
1) Natural polymers like polysaccharide
2) Semi-synthetic polymers like derived from cellulose
3) Synthetic polymers like based on vinyl and acrylic monomers.
Natural polymers A group of carbohydrate polymers of this class are obtained from plant exudates, gums, and extracts mainly include polysaccharides. They can absorb large quantities of water and swell. They find wide range of pharmaceutical applications that includes their use as binder, disintegrant in tablets, emulsifiers, suspending agents, and gelling agents and also as sustaining agents in solid dosages1.Pharmaceutical application most economically important are guar gum, having combination of galactose and mannose units.
Semi-syntheticpolymersImportant polymers in this class are known as cellulose ethers containing ethyl ether of cellulose where hydroxyl radicals of cellulose are replaced by ethoxy groups. Cellulose ethers are further classified into nonionic includes hydroxypropyl methylcellulose and anionic includes sodium carboxymethyl cellulose.
Synthetic polymersImportant polymers in this class are generally derived from vinyl and acrylic monomers. These polymers have a wide capacity to absorb water due to polar functional groups on their chain backbones. Some important synthetic polymers include cross-linked polyacrylamide, hydroxyethyl methacrylate, polyvinyl alcohol, polyacrylic acid, polyacrylate etc.
In recent years, considerable attention has been focused on hydrophilic polymers in Pharmaceutical sector, for example, its properties are of fundamental importance for the controlled release of drug in the gastrointestinal tract (GIT)2, as well as carrier for colon targeted for drug in the treatment of colorectal cancer3. The current demand for guar gum outstrips supply and guar being introduced into new emerging area. Taking into consideration that guar gum polymer is a cheap, easily available and non-toxic4. Gaur gum exhibits several favorable properties, such as biocompability and biodegradability5. Natural polysaccharides such as gaur gum are not digested in human stomach or small intestine, but are degraded in the colon by resident bacteria6. Guar gum is reported to be potential carriers for novel colon specific drug delivery7, 8. In pharmaceutical formulations, guar gum is used as a binder, disintegrant9-11 (see Table 1), suspending agent, thickening agent and stabilizing agent12, 13. Guar gum has been investigated as a potential adjuvant for swellable controlled drug delivery systems. Therapeutically, gaur gum has been used as part of the diet of patients with diabetes mellitus14, 15. It has also been used as an appetite suppressant in tablet form. Guar gum is new effective cancer chemopreventive and/or an anti-inflammatory activity has become an important worldwide strategy in cancer prevention16. It was also found to have the ability to bind toxic substances to carry them out of the body, and to significantly decrease the levels of blood sugar, cholesterol, triglycerides, and lipids in normal and diabetic rodents17, 18.
2. CHEMICAL STRUCTURE AND MANUFACTURING PROCESS OF NATURAL HYDROPHILIC POLYMER
2.1. Guar gum
2.1.1. Structure and properties
Guar bean have a large endosperm that contains galactomannan gum, a substance which forms a gel in water, commonly known as guar gum (Cyamopsis tetragonolobus, family Leguminosae).The gum consists of 85% guaran, a water soluble polysaccharide containing linear chains of (1→4)-β -D-mannopyranosyl units with α-D-galactopyranosyl units attached by (1→6) linkages19 (Figure. 1). The ratio of galactose to mannose is 1:2. Generally, galactomannans properties depend on their chemical structure, such as chain length, availability of cis-OH groups, steric hindrance, degree of polymerization and additional substitutions20 which resulted in considerable variations in their functional characteristics. Guar gum has five to eight times the thickening power of starch and has many uses in cosmetics, food product and pharmaceutical formulations. It was reported that guar gum was first used for food products in the United State in 194921. The largest market for guar gum (EU food additive code E412) is in the food industry. The most importance property as an ability to get hydrate rapidly in cold water to attain uniform and very high viscosity at relatively low concentrations. Apart from being the most effective emulsifier, thickener, binder, disintegrant and stabilizer decidesits application in the technology of a drug form. It is used in the production of ointments, hydrogels, for modification of solution viscosity, stabilization of emulsion and also as a binding agent in the production of tablets22.
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