Grace I Ebiekpi¹, Emmanuel C Otakagu², Mbang N Femi-Oyewo³, Stephen O Majekodunmi¹, Ema E Uduk¹, Emmanuel O Olorunsola¹

Abstract

Purpose: To formulate enteric-coated osmotic tablets for colon-targeted delivery of hydrocortisone. Methods: Nine core tablet batches were prepared with varying amounts of potassium chloride (osmogen), polyethylene glycol 4000 (solubilizing agent), starch (wicking agent), and microcrystalline cellulose (binder). The core tablets, each containing 20 mg hydrocortisone, were coated sequentially with a cellulose acetate (semi-permeable) membrane and Eudragit S-12,5-P/PEG 400 (enteric polymer) system. In vitro dissolution was assessed over a period of twelve hours across physiologically relevant pH conditions. Results: The enteric coating suppressed drug release to approximately 3 % during the initial two hours (pH 1.2), with only 3.4 – 5.1 % cumulative release after four hours at pH 4.5. Substantial release was initiated at pH 7.2, with the majority of hydrocortisone released during the final six-hour phase. Formulations B6 (containing 20 % osmogen and 1.67 % binder) and B7 (containing 13.33 % osmogen and 8.33 % binder) exhibited optimal colon-targeting, achieving 95.20 % and 95.30 % total release respectively. Release kinetics were predominantly first-order, with transport governed by non-Fickian (anomalous) diffusion. Conclusion: Enteric-coated osmotic tablets containing hydrocortisone provide a site-specific colonic delivery, with only minimal premature drug loss in the upper gastrointestinal tract.