Formulation Development, Optimization, and Characterization of Cilnidipine-Loaded Self-microemulsifying Drug Delivery System

Abstract

Cilnidipine, a 2, 4-dihydropyridine antihypertensive, is poorly bioavailable and belongs to Biopharmaceutical Classification System Class II. The present study was carried out to develop and evaluate a cilnidipine-loaded self-microemulsifying drug delivery system (SMEDDS) using food grade oil for enhanced pharmacokinetic parameters. The SMEDDS was prepared by low-energy method. A pseudo-ternary phase diagram was developed using triacetin, Tween 20, and Transcutol HP as oil, surfactants, and cosurfactants, respectively. The statistically optimized formulation was obtained and was evaluated for relevant in vitro characterizations. Globule size, zeta potential, and polydispersity index (PDI) of the optimized formulation were found to be 9.045 nm, −2.32 mv and 0.203, respectively, indicating stable and uniformly distributed microemulsion nature of the formulation. Developed SMEDDS of viscosity 31 cps was found to be clear in 500 times dilution in water and phosphate buffer pH 1.2. Selection of the optimized SMEDDS was followed by various formulation characteristics, including goat intestinal membrane permeability. The in vitro dissolution study of optimized SMEDDS exhibited much better result as compared to the marketed tablet of cilnidipine.