Design, Characterization, and Evaluation of Solid-Self-Nano-Emulsifying Drug Delivery of Benidipine with Telmisartan: Quality by Design Approach

The main purpose of this study was to design and develop a solid self-nanoemulsifying drug delivery system (S-SNEDDS) for the oral administration of benidipine (BD) and telmisartan (TEL) using the adsorption method with eucalyptus oil, Transcutol P, and Kolliphor EL via the Box-Behnken design approach. The prepared SNEDDS formulations were characterized using FTIR, DSC, SEM, and PXRD techniques and evaluated for zeta potential, refractive index, drug concentration, resistance to dilution, viscosity, and thermodynamic stability. Additionally, <i>in vitro</i> and stability studies were conducted. The results revealed that all prepared formulations (BT1-BT15) exhibited favorable zeta potential (17.2-28.39 mV) and polydispersity index (PDI) values (0.226-0.354). Among them, formulation BT11 demonstrated a desirable droplet size of 175.12 ± 2.70 nm, a PDI of 0.226, a zeta potential of -24.98 ± 0.18 mV, a self-emulsification time of 53.00 ± 2.10 s, a transmittance percentage of 99.6 ± 0.3%, and a drug release of 92.65 ± 1.70% within 15 min. BT11 exhibited significantly faster drug release compared to the commercially available product benidipine T (4 mg/40 mg) and the pure drugs BD and TEL, releasing more than 96% of both drugs in 0.1 N HCl within 60 min. Furthermore, BT11 demonstrated stability throughout the product's stability testing. These findings suggest that the oral S-SNEDDS formulation of BD and TEL can enhance the drugs' water solubility, potentially improving therapeutic outcomes and increasing patient compliance.