Abstract

OSMOTIC TABLET FOR COLON SPECIFIC DRUG DELIVERY

Rajneesh Kumar*, Dr. Awani Kumar Rai, Prof (Dr.) Ranjit Singh

ABSTRACT

A microbially triggered colon-targeted osmotic pump (MTCT-OP) was developed based on both the gellable property at acid conditions and colon-specific biodegradation of pectin. The SEM indicated that the pectin was accessible to enzymic degradation which allowed the in situ formation of delivery pores for releasing drug under conditions that may be expected to pertain in the colon, the number of pore being dependent on the initial level of pore former in the membrane. Dexamethasone release from the developed formulation was inversely proportional to the osmotic pressure of the release medium. The parameter of membrane permeability complied well with literature data, confirming that osmotic pumping mechanism was the major principle of drug release. The effects of different formulation variables were studied to select the optimal formulation. Drug release was directly proportional to the initial level of pore former. Level of pH modifier (citric acid) affected the viscosity of chitosan solution, resulting in the change of osmotic pressure in the core tablets. The amount of chitosan in core formulation had a profound effect on the amount of drug release. An optimal core formulation that benefited from suspending and osmotic effect of chitosan has been developed. The enteric-coating membrane could prevent CA membrane containing pore former (pectin) from forming pore or rupture before SCF dissolution procedure, and no significant difference in release profiles could be found when the level of enteric-coating membrane differed. MTCT-OP exhibited gastric and small intestine resistance but were susceptible to bacterial enzymatic attack, and the potential of MTCT-OP as a carrier for drug delivery to the colon was confirmed in simulated physiological GIT conditions. Thus the developed system was found to be a potential system for targeting and controlling the release of dexamethasone to the colon.

Keywords: Chitosan, dexamethasone, eudragit L-100-55, osmotic tablet.