In Vitro and in Vivo Evaluation of Okra Polysaccharide - Based Colon - Targeted Drug Delivery Systems

Colon targeted tablet formulation was developed using okra polysaccharide (Abelmuschus esculentus) as a microbially triggered material and also as the carrier. Okra polysaccharide was isolated from Abelmuschus esculentus and used for tablet formulation with Ibuprofen as model drug. The matrix tablets with four different proportions of the okra (20%, 30%, 40% & 50%) with 1% ethyl cellulose in all the four formulations and the formulations were coded as WO1, WO2, WO3, & WO4. In all the formulations constant 100 mg Ibuprofen were incorporated. The formulations were evaluated for their hardness, weight variation, friability, and drug content and were characterized by FTIR. Matrix tablets were subjected to in vitro drug release studies. The release studies were carried out for 2 hours in pH 1.2, 3 hours in pH 7.4 phosphate buffer and for 10 hours in pH 6.8 PBS. The % Release of these formulations i.e. WO1, WO2, WO3 & WO4 were found to be 20.75, 18.48, 13.37 & 11.99 respectively at 5 hour. The fifth matrix tablet (WO5) with 10% ethyl cellulose, 40% okra polysaccharide and 100 mg ibuprofen was formulated. The % cumulative release of this formulation (WO5) was found to be 4.59 at 5 hour. Among the above, WO3 was chosen as the optimized formulation for further studies. The in vitro dissolution studies were carried out with pH 1.2, pH 7.4 and the study continued in pH 6.8 PBS with rat cecal matter at 6th hour in simulated colonic fluid in order to mimic conditions from mouth to colon. The post five hour studies were carried out without rat cecal also as a control. The observation made was that the maximum release was 98.09% at 10th hour with rat cecal matter and a mere 32.70 % and 46.98% without rat cecal matter at 8 and 10 hour respectively. These findings were confirmed by in vivo investigation using X-ray images of rabbits ingested with okra matrix tablets (WO5) containing barium sulphate as contrast medium instead of Ibuprofen. The tablet began to disintegrate at 8 hour of tablet ingestion. These observations drive us to conclude that the okra polysaccharide under investigation has the potential to carry the drug almost intact to the intended site i.e. Colon where it undergoes degradation due to the presence of anaerobic microbes there. Thereby both the aims contemplated are achieved.