Gellan Gum: A Case Study

Gellan gum is an anionic deacetylated exocellular polysaccharide secreted by Pseudomonas elodea with a tetrasaccharide repeating unit of one á-L-rhamnose, one â-D-glucuronic acid and two â-D-glucuronic acid residues 30. It has the propensity of gelation which is temperature reliant or cations induced .This gelation involves the formation of double helical junction zones followed by aggregation of the double helical segments to form a three-dimensional network by complexation with cations and hydrogen bonding with water 31. The formulation consisted of gellan solution with calcium chloride and sodium citrate complex. When administer orally, the calcium ions are released in acidic environment of stomach leading to gelation of gellan thus forming a gel in situ 32. In situ gelling gellan formulation as vehicle for oral delivery of theophylline is reported.Alginic acid

Alginic acid is consist of β-D-mannuronic acid and α-L-glucuronic acid residues joined by 1,4-glycosidic

Thermo reversible gels mostly prepared from poloxamers are predominantly used.[38] The suitability of poloxamer gel alone or with the addition of hydroxyl propyl methyl cellulose (HPMC), sodium carboxy methyl cellulose (CMC) or dextran was considered for epidural administration of drugs in vitro.[39] The compact gel depot acted as the rate limiting step and significantly extended the dural permeation of drugs in comparison with control solutions. J. M. Barichello et al. evaluated Pluronic F127 gels, which contained either insulin or insulin-PLGA nanoparticles with conclusion, that these formulations could be used as a controlled delivery system. Likewise, poloxamer gels were tested for intramuscular and subcutaneous administration of human growth hormone[42] or with the aim to develop a long acting single dose injection of