A Pharmacokinetic study of once daily Efavirenz 400 mg versus 600 mg in Thai HIV-1 infected subjects.

Efavirenz Pharmacokinetic evaluation supports once-daily dosing (T1/2 is 10-52 hours). The recommended dosage of efavirenz in combination with nucleoside reverse transcriptase inhibitor (NRTI) and/or protease inhibitor (PI) is 600mg orally, once daily.

In Thai populations, many ARV levels are very high. We believe that 600 mg efavirenz is too high for Thai people and would like to see the pharmacokinetic data and safety and efficacy of efavirenz at 400 mg.

Inclusion Criteria:

• Age > 18 years of age or older with HIV-1 infection
• Who are on stable PI-based highly active antiretroviral therapy and have HIV-1 RNA <50 copies/ml within 6 months.
• No active opportunistic infection.
• Sexually active subjects must be willing to use an effective form of birth control.
• Able to provide written informed consent.

Exclusion Criteria:

• Pregnant or breast-feeding females are excluded.
• Inability to understand the nature and extent of the study and the procedures required.
• ALT/ AST more than 5x upper limit
• Relevant history or current condition, illness that might interfere with drug absorption, distribution, metabolism or excretion.
• Use of concomitant medication that may interfere with the pharmacokinetics of efavienz
• History of sensitivity/idiosyncrasy to the drug or chemically related compounds which may be employed in the study.
• Active drug abuse