Influence of Cytochrome P2B6 on Efavirenz Dose in HIV-infected Thai Patients

Influence of Cytochrome P2B6 on Efavirenz Dose in HIV-infected Thai Patients in a Prospective Randomized Controlled Trial: a Proof-of-concept Study

Genetic polymorphisms of cytochrome P450 2B6 (CYP2B6) are associated with lower rate of EFV metabolism and lead to high exposure, as well as a higher risk of neuropsychiatric adverse event especially homozygous variant CYP2B6 *6/*6. This trial was designed to compare the proportion of patients who had undetectable HIV RNA at 24 weeks after ART initiation between patient who did CYP 2B6 guided EFV dose and who did not.

Inclusion Criteria:

• Age ≥18 years old
• Anti-HIV positive
• Naïve to antiretroviral drugs
• Meet the criteria to start ART to Thai National guidelines
• Sign inform consent

Exclusion Criteria:

• Body mass index (BMI) >25 kg/m²
• Pregnant women or breastfeeding
• Received drugs that may have interaction with EFV e.g. rifampicin, fluconazole (400-800 mg), ergot alkaloid, midazolam, triazolam, ritonavir, carbamazepine, phenytoin, phenobarbitone, St John's Wort
• Having active opportunistic infections e.g. tuberculosis, cryptococcosis, histoplasmosis, penicillosis
• Hepatic dysfunction as indicated by:
• Transaminases >5-10 × the upper limit of normal
• ALP >5-10 × the upper limit of normal
• Total bilirubin >2.5-5 × the upper limit of normal