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

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. 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. 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. 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.