ICAAC: Nevirapine and rifampicin can be safely used together

Nevirapine-based antiretroviral therapy may be a safe and effective option for patients who need to take anti-tuberculosis treatment containing rifampicin at the same time as their anti-HIV drugs, according to preliminary data from a study conducted in Thailand and presented to the 45^th Interscience Conference on Antimicrobial Agents and Chemotherapy in Washington DC on Friday.

In resource-limited settings, including Thailand, HIV treatment regimens containing nevirapine are often used at the same time as tuberculosis therapy including rifampicin. There are concerns that concentrations of nevirapine can be reduced if rifampicin is taken at the same time, but data on concomitant use of the two drugs is limited.

Therefore Thai and Dutch investigators designed a study comparing trough plasma levels of nevirapine in patients taking rifampicin at the same time as nevirapine, d4T and 3TC with trough plasma levels of nevirapine in individuals taking the same anti-HIV treatment regimen but who were not taking the anti-tuberculosis drug. Plasma levels of nevirapine were measured eight and twelve weeks after starting HIV and tuberculosis therapy. Data were also gathered to compare liver function at eight and twelve weeks, and virologic and immunologic response to HIV therapy at twelve weeks.

A total of 140 patients, equally divided between each treatment group, were recruited to the study. The patients had a mean age of 36 years, 68% were men and the median CD4 cell count was 33 cells/mm³ in the group receiving rifampicin and 29 in the nevirapine-only group.

Although a signficantly higher proportion of the rifampicin group had nevirapine plasma trough levels below 3.4mg/l, at eight and twelve weeks mean trough plasma levels of nevirapine were comparable between both groups of patients. 88% of patients in the rifampicin group with a nevirapine trough level below 3.4mg/l achieved a viral load below 400 copies/ml at week 24.

Nor did the investigators observe any difference in liver function, indicated by mean ALT levels between the two treatment groups at weeks eight and twelve (p = 0.67). In addition, patients taking rifampicin achieved a viral load below 50 copies/ml as quickly as patients only taking HIV therapy (p = 0.43), and both groups of patients experienced comparable changes in their median CD4 cell count after twelve weeks of treatment (p = 0.58).

“Nevirapine-based antiretroviral therapy may be an option for HIV-infected patients who receive rifampicin”, conclude the investigators. They caution, however, “further study of long-term virological and immunological outcomes is needed.”