Hualu Wu,1 Qian Liu,2 Yuxin Shen,1 He Qi,3 Jiade Zhao,3 Qiaoying Li,4 Hailun Xia,1 Ren-Ai Xu,1 Lu Shi1 

1Department of Pharmacy, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, People’s Republic of China; 2Department of Clinical Laboratory, Aerospace Center Hospital, Beijing, People’s Republic of China; 3College of Basic Medicine and Forensic Medicine, Henan University of Science and Technology, Luoyang, Henan, People’s Republic of China; 4Lishui Liandu District Adverse Drug Reaction Monitoring Station, Lishui, Zhejiang, People’s Republic of China

Correspondence: Lu Shi; Ren-Ai Xu, The First Affiliated Hospital of Wenzhou Medical University, Nanbaixiang Street, Wenzhou, 325000, People’s Republic of China, Tel/Fax +86 105 557 9706, Email shilu199004@163.com; xra@wmu.edu.cn

Purpose: The purpose of this study was to establish an in vitro incubation system and an in vivo model to investigate the potential kinetic interactions of macitentan with imperatorin and curcumin, and to validate the potential inhibitory mechanisms using molecular docking.
Methods: In vitro, the enzyme kinetic profile of macitentan was explored in rat liver microsomes (RLM) and human liver microsomes (HLM). Furthermore, molecular docking technique was used to study the sites of action of macitentan, imperatorin, and curcumin with CYP 3A4. In vivo, the pharmacokinetic parameters of macitentan were investigated in Sprague-Dawley (SD) rats administered the drug orally, both as a single agent and in combination with imperatorin and curcumin.
Results: In vitro, the results indicated that imperatorin and curcumin could inhibit the metabolism of macitentan, with IC50 values of 6.58 μM and 10.86 μM in RLM and 6.97 μM and 5.71 μM in HLM, respectively. And in the study of inhibition type, in RLM, the inhibition types of imperatorin and curcumin on macitentan were mixed and non-competitive, respectively; in HLM, the inhibition types of imperatorin and curcumin on macitentan were both mixed. Furthermore, additional molecular docking studies demonstrated that both imperatorin and curcumin occupied the CYP3A4 site. In vivo, the result showed significant increases in AUC(0-t), AUC(0-∞), Tmax, t1/2, and Cmax for macitentan while a decrease in CLz/F when combined with imperatorin. The metabolite ACT-132577 exhibited substantial increases in t1/2, Tmax, and Cmax. Combined with curcumin, the AUC(0-∞) and Tmax of macitentan were significantly increased, while CLz/F was significantly decreased. Conversely, the metabolite ACT-132577 exhibited a substantial decrease in CLz/F, accompanied by notable increases in AUC(0-∞) and Tmax.
Conclusion: In vitro and in vivo studies revealed that imperatorin and curcumin exhibited inhibitory effects on the metabolism of macitentan. Furthermore, molecular docking revealed that the metabolic inhibition of macitentan by imperatorin and curcumin occurred through binding to the site on CYP3A4. However, further investigation is necessary to ascertain whether this phenomenon will occur in humans.

Keywords: pharmacokinetics, molecular docking, UPLC-MS/MS, inhibition mechanism