Monpat ChamnanphonRattanaporn SukprasongAndrea GaedigkWeerawat ManosuthiPajaree ChariyavilaskulSupeecha WittayalertpanyaNapatrupron KoomdeeThawinee JantararoungtongApichaya PuangpetchChonlaphat SukasemRamathibodi HospitalChulalongkorn UniversityUMKC School of MedicineFaculty of Medicine Ramathibodi Hospital, Mahidol UniversityThailand Ministry of Public HealthSrinakharinwirot UniversityChildren's Mercy Kansas City2022-08-042022-08-042021-01-01Pharmacogenomics and Personalized Medicine. Vol.14, (2021), 915-926117870662-s2.0-85111767841https://repository.li.mahidol.ac.th/handle/20.500.14594/76352Purpose: Plasma efavirenz (EFV) concentrations within therapeutic levels are essential to successfully treat patients suffering from human immunodeficiency virus (HIV) type 1. In addition to the drug-metabolizing enzyme CYP2B6, other phase II drug-metabolizing enzymes and transporters may have an important role in the pharmacokinetics of EFV. Thus, the influence of phase II drug-metabolizing enzymes and drug transporters on plasma EFV levels was investigated in Thai HIV patients receiving EFV. Patients and Methods: Genotyping was performed by TaqMan® real-time PCR in 149 HIV-infected Thai adults, and plasma efavirenz concentration was measured by a validated high-performance liquid chromatography in 12 hours after dosing steady-state plasma sam-ples at week 12 and 24. Results: Patients with three or more copies of SULT1A1 had significantly lower median plasma EFV concentrations than those carrying two copies at week 12 (p=0.046) and SULT1A1*2 (c.638G>A) carriers had significantly lower median plasma EFV concentrations compared to those not carrying the variant at week 24 (p=0.048). However, no significant association was found after adjusting for CYP2B6 genotype. Conclusion: Genetic variation in a combination of SULT1A1*2 and SULT1A1 copy number may contribute to variability in EFV metabolism and thereby may impact drug response. The influence of a combination between the SULT1A1 and CYP2B6 genotype on EFV pharma-cokinetics should be further investigated in a larger study population.Mahidol UniversityBiochemistry, Genetics and Molecular BiologyPharmacology, Toxicology and PharmaceuticsArticleSCOPUS10.2147/PGPM.S306358