A Survey on Mucoadhesive Thermoreversible Drug Delivery System with special Emphasis on Recto-Anal Region for the Treatment of Internal Hemorrhoids

Abstract

The concept of combination of thermo reversibility and mucoadhesion has achieved a much valuable interest in various fields of pharmaceutics. Mucoadhesive drug delivery systems interact with the mucus layer covering the mucosal epithelial surface, and mucin molecules and increase the residence time of the dosage form at the site of absorption. Thermoreversible gels are the hydrogels that are liquids at room temperature but undergo gelation when in contact with body fluids or change in pH. A major problem faced by conventional formulation in various routes of administration viz. nasal, ocular, vaginal, rectal, etc is drainage of instilled formulation, poor patient compliance as in the case of vaginal and rectal delivery system. Also, blurred vision and irritation to mucosa is observed in the case of ocular and nasal delivery respectively. The drainage of the formulation results in inaccurate dose delivery thus decreasing the bioavailability of the drug which demands an increase in the frequency of the administration. To overcome these limitations, there is need of novel delivery system such as thermoreversible mucoadhesive insitu gel which provides an ease of administration and improved patient compliance as these smart delivery system is free flowing liquid at ambient temperature and gels at physiological temperature which is higher than the LCST (low critical solution temperature) of thermoreversible polymer. The combined effect of mucoadhesion and thermoreversible property will enhance prolongation of residence time of dosage form and the accuracy of the dose in body cavity respectively, leading to increased bioavailability of the drug. This review focuses on benefits of mucoadhesive thermoreversible system of drug delivery through rectum for the treatment of internal hemorrhoids.