Formulation of mucoadhesive gastric retentive drug delivery using thiolated xyloglucan

Tamarind seed xyloglucan is a polymer reported to possess mucoadhesive property. In the present work, role of cysteine derivative of tamarind seed polysaccharide (thiomer) to enhance the mucoadhesion and its influence on drug permeation has been studied. The xyloglucan was first chemically modified to carboxymethyl derivative which was further converted to thiomer by conjugation with cysteine in presence of a coupling agent, EDAC. The matrix tablets of simvastatin prepared using thiomer demonstrated drug release retardation, increased mucoadhesion force and increased ex vivo permeation, the same were proportional to the increase in the amount of thiomer. The in vivo residence of thiomer placebo was more than 7 h in rabbit. Pharmacokinetic evaluation in rabbits indicated higher AUC for the formulation with highest content of thiomer and level 'A' correlation could be established from the generated dissolution and bioavailability data.