Development and Evaluation of a pH-Responsive Nano suspension of Rivaroxaban for Enhanced Oral Delivery

Rivaroxaban, a Biopharmaceutics Classification System (BCS) Class II drug, exhibits poor aqueous solubility, leading
to variable oral bioavailability and suboptimal therapeutic performance. The present study aimed to develop and
evaluate a pH-responsive nanosuspension of rivaroxaban to enhance its solubility, dissolution rate, and intestinal drug
release. Nanosuspension was prepared using the antisolvent precipitation method combined with high-speed
homogenization and ultrasonication. Preformulation studies confirmed poor aqueous solubility and crystalline nature of
the drug. Compatibility studies using FTIR and DSC indicated no significant interaction between drug and excipients.
The optimized formulation exhibited a particle size of 182 nm with a low polydispersity index (0.24), indicating uniform
distribution. Zeta potential was found to be −32.6 mV, suggesting good physical stability. The formulation showed high
drug content (98.3%) and entrapment efficiency (88.3%). In-vitro dissolution studies demonstrated minimal drug release
in acidic conditions and significantly enhanced release (~96%) in intestinal pH, confirming pH-responsive behavior.
Stability studies indicated negligible changes in physicochemical parameters over time. The results suggest that the
developed nanosuspension is a promising strategy for improving the oral delivery of rivaroxaban and other poorly
soluble drugs.