In vitro and in vivo assessment of cytochrome P450-mediated herb-drug interaction of Ssang-hwa-tang

► SHT showed inhibitory activity toward CYP1A2. ► SHT-induced CYP1A2 inhibition was mixed reversible inhibition. ► Hepatic expression/activity of CYP2E1 increased as a result of SHT extract treatment. ► Fermentation using Lactobacillus strains attenuated the SHT-induced CYP1A2 inhibition.