Background: Neuropsychiatric side effects (NPSEs) occur in a significant proportion of subjects after initiation of efavirenz (EFV) and may limit its use in certain patients.

Objectives: To evaluate the incidence and severity of NPSEs and antiviral efficacy of EFV given as a stepped dosage over 2 weeks versus the usual dosage.

Methods: Randomized, double blind, multicentric clinical trial in which a progressive dosage (arm A: 200 mg qd for 6 days, 400 mg qd for 7 days and 600 mg qd from day 14 forward) was compared with conventional administration (arm B: 600 mg qd from the first day). All patients received additional treatment with 2 NRTIs.

The incidence and intensity of NPSEs and sleep disorders were assessed using a Likert-type scale specifically designed. Efficacy was assessed by percent of virological failures.

Inclusion Criteria:

• Age older than 18 years
• HIV-1 infection
• Women of child-bearing age: negative pregnancy test
• Ability to understand and sign a written consent form

Exclusion Criteria:

• Pregnancy..
• Illegal drug or methadone use.
• Major psychiatric disease antecedents or starting new psychotropic agents in the last 4 weeks
• Concomitant treatment with rifamycins, protease inhibitors or drugs which interfere the pharmacokinetic of efavirenz.
• Hepatic insufficiency