Nanostructured Sphingosomes for Carisoprodol Delivery: Optimization Using 23 Factorial Experimental Design

Objective: To develop and optimize a new sphingosomal formulation of carisoprodol to enhance entrapment efficiency, prolong the drug release for 24 h, leading to a reduction in dosing frequency and enhanced patient compliance. Methods: The sphingosomes containing 90 mg of carisoprodol were prepared as per a 23 factorial design by employing ceramide, cholesterol, and PEG (polyethylene glycol) by the thin-film method. The particle size, zeta potential, entrapment efficiency, and release parameters (percent drug released in 24 h) of the sphingosomes were investigated using an ANOVA (analysis of variance) with a 23 factorial design. This formulation encapsulates carisoprodol in sphingolipid-rich lipid vesicles to achieve sustained release, enhanced stability, and site-specific delivery, particularly for skeletal muscle pain and spasms. Results: All the formulations were prepared using ceramide, cholesterol, and PEG and evaluated for particle size, zeta potential, entrapment efficiency, and In vitro drug release. The particle sizes of the sphingosomes range from 150.3±1.31 nm to 2631.7±2.31 nm, while the zeta potential varies from -46.3±0.12 mV to 1.5±0.15 mV. Entrapment efficiency ranges from 50±0.75% to 93±1.35%. In vitro diffusion profiles of carisoprodol formulations were analysed using various kinetic models, and the release characteristics of formulations F-1 to F-8 were determined. Conclusion: The optimized Carisoprodol-loaded sphingosomes (F2) exhibited high entrapment efficiency, sustained drug release for 24 h, reduced dosing frequency, and enhanced patient compliance. These results demonstrate the potential of sphingosomes as an innovative drug delivery system for carisoprodol.