Drug-Silica-Cellulose Ternary Matrix for the Oral Delivery of Cyclosporine A: In vitro and in vivo evaluation

Purpose: Supersaturated formulations have been widely explored for improving the oral bioavailability of drugs by using mesoporous silica (MS) to generate supersaturation via molecular adsorption; however, this is followed by precipitation. Several precipitation inhibitors (PI) have been explored to prevent precipitation and maintain the drug in solution for a longer period. However, the combined approach of MS and PIs, the impact of MS and Silica, and the loading of high-molecular-weight neutral molecules such as Cyclosporine A (CsA) have not yet been explored. The present study aimed to explore the impact of MS and a hydroxypropyl methylcellulose (HPMC) matrix on the supersaturation and bioavailability of the neutral drug CsA.

Methods: A CsA-loaded mesoporous silica/HPMC ternary matrix and CsA-HPMC and CsA-MS controls were prepared, and physicochemical characterization was carried out. The ternary matrix and controls were investigated for the Non-sink Mini FaSSIF dissolution and biorelevant transfer studies. Furthermore, drug release modeling was performed using DDSolver, and pharmacokinetic studies were performed to assess the impact on oral bioavailability compared with the marketed formulation.

Results: The study suggested that the co-loaded CsA, HPMC, and MS demonstrated higher supersaturation than CsA-loaded silica and CsA-HPMC controls. A significant improvement in FaSSIF single medium (2-fold) and biorelevant transfer (3.37-fold) increase in the dissolution profile was observed for the co-loaded CsA-MS-HPMC samples. The in vitro dissolution profile was corroborated by pharmacokinetic studies, which showed a 1.19-fold higher oral bioavailability of CsA-MS-HPMC compared to that of CsA-MS and CsA-HPMC.

Conclusion: The pharmacokinetics indicated that CsA-MS-HPMC co-loaded samples demonstrated supersaturation and improved bioavailability compared with the physical mixture.