Bulleyaconitine A is a sensitive substrate and competitive inhibitor of CYP3A4: One of the possible explanations for clinical adverse reactions

• Published in: Toxicology and applied pharmacology Vol. 445; p. 116024
• Main Authors: Li, Xiaocui, Ou, Xiaowen, Ni, Jiadong, Xu, Yihong, Zuo, Huilin, Fu, Yu, Yang, Caihua, Zhao, Zhongxiang, Li, Na, Zhou, Hua, Zhang, Rong, Liu, Zhongqiu, Fu, Ling, Zhu, Lijun
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.06.2022
• Subjects: Aconitine - analogs & derivatives; Aconitine - pharmacology; Adverse reaction; Animals; Bulleyaconitine A; Cytochrome P-450 CYP3A - metabolism; Cytochrome P450 enzymes; Drug Interactions; Drug-drug interactions; Human liver microsomes; Ketoconazole - pharmacology; Membrane Proteins - pharmacology; Metabolism; Mice; Microsomes, Liver - metabolism; Saccharomyces cerevisiae Proteins - pharmacology; KCZ; CYPs; MRT; AUC; LDH; MA; DDIs; Bulleyaconitine A; 1-OH MDZ; AC; MDZ; Adverse reaction; Cytochrome P450 enzymes; RLMs; CK; HLMs; S100B; Metabolism; MMP9; LD50; CLint; BLA; HA; Human liver microsomes; Drug-drug interactions
• ISSN: 0041-008X; 1096-0333
• DOI: 10.1016/j.taap.2022.116024

Bulleyaconitine A (BLA), a toxic Aconitum alkaloid, is a potent analgesic that is clinically applied to treat rheumatoid arthritis, osteoarthritis and lumbosacral pain. BLA-related adverse reactions occur frequently, but whether the underlying mechanism is related to its metabolic interplay with drug-metabolizing enzymes remains unclear. This study aimed to elucidate the metabolic characteristics of BLA and its affinity action and mechanism to drug-metabolizing enzymes to reveal whether BLA-related adverse reactions are modulated by enzymes. After incubation with human liver microsomes and recombinant human cytochrome P450 enzymes, we found that BLA was predominantly metabolized by CYP3A, in which CYP3A4 had an almost absolute advantage. In vitro, the CYP3A4 inhibitor ketoconazole noticeably suppressed the metabolism of BLA. In vivo, the AUC0-∞ values, cardiotoxicity and neurotoxicity of BLA in Cyp3a-inhibited mice were all obviously enhanced (P < 0.05) compared to those in normal mice. In the enzyme kinetics study, BLA was found to be a sensitive substrate of CYP3A4, and its characteristics were consistent with substrate inhibition (Km = 39.36 ± 10.47 μmol/L, Ks = 83.42 ± 19.65 μmol/L). BLA was further identified to be a competitive inhibitor of CYP3A4 with Ki = 53.64 μmol/L, since the intrinsic clearance (CLint) of midazolam, a selective CYP3A4 substrate, decreased significantly (P < 0.05) when incubated with BLA together in mouse liver microsomes. Overall, BLA is a sensitive substrate and competitive inhibitor of CYP3A4, and clinical adverse reactions of BLA may mechanistically related to the CYP3A4-mediated drug-drug interactions. •BLA is a sensitive substrate and competitive inhibitor of CYP3A4.•The toxicity of BLA may increase when CYP3A4 is inhibited.•Adverse reactions of BLA may mechanistically relate to CYP3A4-mediated DDIs.