Nevirapine, efavirenz and Kaletra regimens best for treatment naive

Michael Carter
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This article is more than 21 years old.

Initial HAART regimens including the NNRTIs efavirenz or nevirapine, or the boosted protease inhibitor Kaletra are most likely to achieve a sustained reduction in viral load below 500 copies/mL in HIV-positive treatment naive individuals, according to the results of an international observational study involving over 1,000 patients presented as a poster to the 43rd Interscience Conference on Antimicrobial Agents and Chemotherapy in Chicago on September 15th.

Investigators from the US HIV InsightTM study and the Dutch ATHENA cohort analysed data from 1,119 antiretroviral naive patients who started HAART between 1999 and 2002.

Five commonly used HAART regimens were compared. Three were based on protease inhibitors: nelfinavir (339 patients); indinavir boosted by low dose ritonavir (48 individuals); and, Kaletra (lopinavir with low dose ritonavir, 61 patients). The remaining two regimens examined in the study were NNRTI based, with 400 people taking nevirapine and 271 efavirenz.

Glossary

boosting agent

Booster drugs are used to ‘boost’ the effects of protease inhibitors and some other antiretrovirals. Adding a small dose of a booster drug to an antiretroviral makes the liver break down the primary drug more slowly, which means that it stays in the body for longer times or at higher levels. Without the boosting agent, the prescribed dose of the primary drug would be ineffective.

observational study

A study design in which patients receive routine clinical care and researchers record the outcome. Observational studies can provide useful information but are considered less reliable than experimental studies such as randomised controlled trials. Some examples of observational studies are cohort studies and case-control studies.

naive

In HIV, an individual who is ‘treatment naive’ has never taken anti-HIV treatment before.

treatment-naive

A person who has never taken treatment for a condition.

chemotherapy

The use of drugs to treat an illness, especially cancer.

Effectiveness was measured according to two outcomes: the time taken for HIV viral load to fall below 500 copies/mL; and, the subsequent time taken for virological failure to occur, assessed as two consecutive viral load measurements above 500 copies/mL.

Results were adjusted according to age, sex, previous NRTI use, year of entry to the study, HIV risk group, country of residence, and baseline CD4 cell count and viral load.

The investigators found that individuals prescribed regimens containing efavirenz, nevirapine or Kaletra, but not indinavir boosted by ritonavir, were significantly more likely to achieve a viral load below 500 copies than those starting a nelfinavir-containing regimen (Hazard Ratios [HR] compared to nelfinavir: 1.7, 95% CI, 1.4 - 2.2, p

Individuals taking the NNRTI-based regimens were significantly less likely than those taking either the nelfinavir or indinavir/ritonavir-containing regimens to experience virological failure (HR compared to nelfinavir: 0.38, 95% CI, 0.21 - 0.69, p=0.002, and 1.7, 95% CI 1.1 - 2.5, p=0.018 respectively). There was a trend for patients to experience failure later on Kaletra compared to nelfinavir, but given the small sample size testing for significance was not possible. There were no significant differences, however, in the time to virological failure between patients taking efavirenz, nevirapine or Kaletra.

The investigators conclude, that of the current common initial HAART regimens, those containing efavirenz, nevirapine and Kaletra offer treatment-naive patients the best opportunity to achieve and maintain HIV suppression.

References

Ghani AC et al. Comparison of the effectiveness of initial HAART regimens in a large observational database. 43rd ICAAC, abstract H-849, Chicago, September 14 - 17th, 2003.

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