- Have been treated with anti-HIV drugs for more than 6 months. Patients must be taking the anti-HIV drugs regularly for at least 4 weeks before they enter the study. Patients must be taking anti-HIV drugs regularly for at least 8 weeks if they have changed from taking protease inhibitor (PI) anti-HIV drugs to non-PI anti-HIV drugs. Any combination without a PI must lower the patient's HIV viral levels, as determined by the patient's physician.