Atripla is a fixed-dose combination tablet comprising 600mg efavirenz, 200mg FTC (emtricitabine) and 300mg tenofovir, manufactured jointly by Bristol-Myers Squibb and Gilead Sciences. Efavirenz is a non-nucleoside reverse transcriptase inhibitor (NNRTI), FTC is a nucleoside reverse transcriptase inhibitor (NRTI) and tenofovir is a nucleotide reverse transcriptase inhibitor (NtRTI). These drugs reduce the amount of HIV in the body and prevent the development of AIDS-defining illnesses.

The standard dose of Atripla is one tablet once a day. The manufacturers advise patients to take it on an empty stomach, before going to bed.

Atripla is the first combination tablet to be licensed that provides all the drugs needed for an anti-HIV regimen, achieving the goal of one tablet once a day to treat HIV infection. It was licensed in the United States for use in HIV-positive adults in July 2006. However, its approval in the European Union is not expected until late 2006, because a third company, Merck & Co., is responsible for producing efavirenz in some European countries.

Atripla's three component drugs are well known and are recommened for use in first-line therapy of patients with HIV-1 infection in British and United States treatment guidelines. Atripla is therefore likely to become a popular option for use in this patient group.

Atripla was licensed on the basis of data from Study 934, which compared efavirenz (Sustiva), FTC (Emtriva) and tenofovir (Viread) taken as separate drugs, to the combination of efavirenz and AZT (zidovudine) plus 3TC (lamivudine) as Combivir. In this study, more patients in the FTC and tenofovir arm achieved viral loads below 400 copies/ml after 48 weeks, largely due to fewer discontinuations due to drug side-effects. A study in HIV-negative subjects revealed that the triple combination tablet produces blood levels equivalent to the three drugs taken separately.

The main side-effects of Atripla are dizziness, nausea, diarrhoea, fatigue, headache and rash. It should not be used by women during the first three months of pregnancy, due to a risk of birth abnormalities caused by efavirenz. It should not be taken by patients with kidney problems (creatine clearance less than 50ml/min).

For more information on Atripla's component drugs, including drug interactions, side-effects and resistance, see efavirenz (Sustiva), FTC (emtricitabine, Emtriva) and tenofovir disoproxil (Viread).