Drug Interactions Among Anti-HIV Agents

Summary

This study examined the interactions of various drugs used to treat HIV infection in order to design larger studies of possible combinations for people who continue to have high viral levels despite combination therapy. HIV-infected patients 18 years of age and older who have a viral load of at least 500 copies/mL; who have received 20 weeks of protease inhibitor therapy, with the same protease inhibitors in combination therapy for the last 12 weeks; and who have never been treated with abacavir, amprenavir or efavirenz were enrolled. All patients will receive 600 milligrams a day of efavirenz (a non-nucleoside reverse transcriptase inhibitor); 300 mg twice daily of abacavir (a nucleoside analog); and 1200 mg twice a day of amprenavir (a protease inhibitor). In addition to these drugs, six patients will receive 500 mg twice a day of ritonavir (a protease inhibitor); six patients will receive 200 mg twice a day of ritonavir; and 10 will receive 1250 mg twice a day of nelfinavir (a protease inhibitor). Patients in the two ritonavir groups (500-mg and 200-mg dose groups) took abacavir and amprenavir for one week and then come to the clinic for blood tests to measure drug levels before taking their morning pills and at 1/2, 1, 2, 4, 8, and 12 hours after taking the medicines. They will then add ritonavir to their treatment regimen. After one week, they will return for blood tests as before. They will then add efavirenz to their regimen and had bloods drawn again after another 1 or 2 weeks. Patients in the nelfinavir group took abacavir, amprenavir and nelfinavir for one week and then have blood sampling as described above for the ritonavir group. They will then add efavirenz to the regimen and repeat the blood tests again after another 1 or 2 weeks. Participants are being seen in the clinic for follow-up only if they wish to continue to participate and if the regimen appears to offer clinical benefit.

Timeline

Start

1998-08

Primary completion

—

Completion

2003-08

Publications

• Background Livington DJ, Pazhanisamy S, Porter DJ, Partaledis JA, Tung RD, Painter GR. Weak binding of VX-478 to human plasma proteins and implications for anti-human immunodeficiency virus therapy. J Infect Dis. 1995 Nov;172(5):1238-45. doi: 10.1093/infdis/172.5.1238.
• Background Faletto MB, Miller WH, Garvey EP, St Clair MH, Daluge SM, Good SS. Unique intracellular activation of the potent anti-human immunodeficiency virus agent 1592U89. Antimicrob Agents Chemother. 1997 May;41(5):1099-107. doi: 10.1128/AAC.41.5.1099.
• Background Winslow DL, Garber S, Reid C, Scarnati H, Baker D, Rayner MM, Anton ED. Selection conditions affect the evolution of specific mutations in the reverse transcriptase gene associated with resistance to DMP 266. AIDS. 1996 Sep;10(11):1205-9. doi: 10.1097/00002030-199609000-00005.

Drugs

Indications