Enhancing Oral Absorption of Orlistat through Gastroretentive Mucoadhesive Pellets: Formulation and Evaluation

Aim: The aim of this study was to develop gastroretentive mucoadhesive pellets of Orlistat to improve its oral bioavailability and enhance its absorption.  Methods: Orlistat pellets were prepared using Hydroxy Propyl Methyl Cellulose (HPMC) K100M, Sodium Carboxy Methyl Cellulose (NaCMC), Carbopol 934P, and Polyvinyl Pyrrollidone (PVP) K30 in varying ratios. Physical characteristics of the tablets were evaluated, and compatibility studies were performed between Orlistat and the excipients. Swelling index, mucoadhesion strength and drug release were measured for each formulation. Drug release kinetics and stability studies were carried out.  Results: The combination of HPMC K100M, NaCMC, Carbopol 934P and PVP K30 provided balanced release and mucoadhesion with F13 showing sustained release up to 16 hours. The calibration curve demonstrated a good linear relationship between Orlistat concentration and absorbance over the range of 10 to 50 ?g/ml. Swelling index increased with time and polymer concentration and mucoadhesion strength increased with polymer viscosity and concentration. Drug release from formulations containing HPMC K100M, NaCMC and Carbopol 934P were 12-14 hours, 10-12 hours and 8-11 hours, respectively. Combination polymers in F10-F13 provided balanced release and mucoadhesion, with F13 showing sustained release up to 16 hours. The drug release followed zero order kinetics with non-Fickian diffusion. Stability studies on the optimized F13 formulation showed no significant changes in appearance, hardness, mucoadhesion or drug release over 3 months.  Conclusion: The combination of HPMC K100M, NaCMC, Carbopol 934P and PVP K30 improved the oral bioavailability and absorption of Orlistat. The study demonstrated the importance of compatibility studies and the use of calibration curves for quantitative analysis. The findings provide valuable insights into the development of drug delivery systems for poorly bioavailable drugs.