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May 8, 2008
Higher-Dose Kaletra Plus Rifampicin Creates Liver Toxicity
Taking Kaletra (lopinavir/ritonavir) at doses higher than generally recommended in conjunction with the tuberculosis (TB) medication rifampicin causes serious side effects including vomiting and liver toxicity, say the authors of a study published in the May 11 issue of AIDS.
A third of all people with HIV worldwide are also infected with TB. Unfortunately, one of the most effective TB drugs, rifampicin, interacts with a majority of the antiretroviral (ARV) drugs—notably protease inhibitors—available in the developing world, where TB incidence is most high. Rifampicin causes the body to produce more of a liver enzyme that processes the ARV drugs, resulting in lower blood levels of those HIV medications. Current guidelines from the World Health Organization (WHO) recommend that doctors prescribe either Sustiva (efavirenz) or Viramune (nevirapine) along with rifampicin, but given the ease with which HIV can become resistant to these drugs, alternatives are desired.
Hanneke Nijland, MSc, from the Radboud University Nijmegan Medical Centre in the Netherlands, and colleagues enrolled 40 HIV-negative study volunteers to determine whether an increased dose of Kaletra along with rifampicin would be safe while also ensuring that the blood levels of Kaletra remained in the recommended range. The protocol for the study involved having volunteers first take 600 mg of rifampicin once a day for six days and then adding either three or four Kaletra tablets twice a day—twice the standard dose—for 10 more days.
Nijland’s team, however, stopped the study after the first group of 11 volunteers had been studied for eight days. This was because nearly all the volunteers were experiencing vomiting and nausea; measurements of liver function were also showing signs of significant toxicity.
The authors call for more research to be done on the interaction of Kaletra and rifampicin, but in people living with HIV who also have tuberculosis, as opposed to HIV-negative volunteers who do not have tuberculosis. Nijland’s team also recommends that the two drugs not be used together in the meantime unless no other options are available, and in that case, to carefully monitor liver function.
