Bhawna Gauri, Dimple Chopra, Shailendra K Singh, Lovekesh Nagpal
ABSTRACT
The objective of our study was to develop single-unit colon targeted drug delivery system of tinidazole using pH dependent methacrylic acid polymers and/or time dependent polymeric combination, which slowly release the drug to colon. Lactose-based tinidazole placebo tablets were coated using various ratios of two co-polymers, Eudragits®L100 and Eudragits®S100 (weight by weight) (w/w) 4:0, 3:1, 2:2, 1:3 and 0:4 respectively by coating method and Ethylcellulose and shellac 5:0, 2.5:2.5, 1:4, 0:5. The tablets were evaluated for various in process quality control parameters, in-vitro drug release studies and in-vivo gamma scintigraphic studies. The in-vitro drug dissolution data obtained from coated tablets demonstrated that dissolution rate of the coated tablets was dependent on (i) polymer combination ratio (ii) pH of media (iii) coating levels of the tablets. The transit profiles in two healthy volunteers by gamma scintigraphy demonstrated that the tablets were able to pass through the stomach and small intestine intact and could safely reach the distal end of the small intestine, where the system began to release the drug contained in the core tablet. For both of the volunteers, disintegration of the tablets occurred in the ascending colon, which had highlighted the potential of this system for colonic drug delivery. The result also demonstrated that the formulation can be adjusted to deliver the drug at any target site of the intestinal region of the gastrointestinal tract on the basis of pH variability. So, it concluded that colon targeted drug delivery system prepared herein, by means of regular coating techniques, were able to achieve site-specific drug delivery targeting to the colon following oral administration and provide a promising strategy to control drug release targeting the desired lower gastrointestinal region.
Keywords: Colon targeting, tinidazole, Gamma Scintigraphy, pH dependent system, time dependent system, In vivo study