Formulation Development, Statistical Optimization and Characterization of the Self-Microemulsifying Drug Delivery System (SMEDDS) of Irbesartan

Background: Irbesartan is an anti-hypertensive BCS class II drug exhibiting poor aqueous solubility, which makes it highly challenging for delivery through the oral route. Based on this fact, a self-microemulsifying drug delivery system (SMEDDS) was designed and characterized for augmenting the aqueous solubility and dissolution rate of irbesartan. Methods: Several blends of oil (Capmul MCM EP), surfactant (Tween 80) and co-surfactant (PEG 600) were screened from the preliminary solubility and pseudo-ternary phase diagram studies. Systematic optimization of the SMEDDS was carried out using 3-factor 3-level Box-Behnken design. Results: The optimized formulation was identified by numerical optimization technique, which revealed faster emulsification time, high percent transmittance and drug content, lower globule size < 100 nm, zeta potential and excellent thermodynamic stability. The optimal formulation unveiled more than 93.3% drug release in vitro within 60 minutes, while the pure drug exhibited only 20% drug release, respectively. Conclusion: Ex vivo permeability and in situ intestinal absorption of drugs was improved nearly 2 to 3- fold by the optimal SMEDDS formulation against the pure drug alone (p < 0.001). Overall, the proposed SMEDDS formulation of irbesartan exhibited a superior biopharmaceutical performance.