Self-nanoemulsifying drug delivery system (SNEDDS) mediated improved oral bioavailability of thymoquinone: optimization, characterization, pharmacokinetic, and hepatotoxicity studies

Thymoquinone (TQ) is an antioxidant, anti-inflammatory, and hepatoprotective compound obtained from the black seed oil of Nigella sativa. However, high hydrophobicity, instability at higher pH levels, photosensitivity, and low oral bioavailability hinder its delivery to the target tissues. A self-nanoemulsifying drug delivery system (SNEDDS) was fabricated using the microemulsification technique to address these issues. Its physicochemical properties, thermodynamic stability studies, drug release kinetics, in vivo pharmacokinetics, and hepatoprotective activity were evaluated. The droplet size was in the nano-range (< 90 nm). Zeta potential was measured to be -11.35 mV, signifying the high stability of the oil droplets. In vivo pharmacokinetic evaluation showed a fourfold increase in the bioavailability of TQ-SNEDDS over pure TQ. Furthermore, in a PCM-induced animal model, TQ-SNEDDS demonstrated significant (p<0.05) hepatoprotective activity compared to pure TQ and silymarin. Reduction in liver biomarker enzymes and histopathological examinations of liver sections further supported the results. In this study, SNEDDS was demonstrated to be an improved oral delivery method for TQ, since it potentiates hepatotoxicity and enhances bioavailability.