Raltegravir effectively decreases HIV viral loads after 24 weeks of use among HIV-positive people who have not responded to other treatments, according to a study published in the April 14 online edition of the journal Lancet. Raltegravir works by blocking an HIV enzyme called integrase. Integrase is one of the three enzymes necessary for HIV to replicate in the body, and integrase inhibitors stop HIV from inserting its genes into uninfected DNA. The other two enzymes necessary for viral replication, reverse transcriptase and protease, already are targeted by a variety of antiretrovirals.
According to an FDA review of raltegravir released ahead of the independent panel's meeting, the drug is effective at treating HIV-positive people who have shown resistance to available treatments. The most common side effects were rash and increased levels of creatine in the blood, according to the review. Other potential side effects include liver injuries and cancer. In clinical trials, a higher number of cancers was found among people taking raltegravir than among those taking a placebo, but the difference could be because of a lower rate of cancer among people in the placebo group, FDA said.
Merck previously said that the drug will be used in combination with standard oral antiretrovirals by HIV-positive people who have developed resistance to their current treatments. Raltegravir will be sold under the brand name Isentress. According to Amy Rose, a Merck spokesperson, the treatment will cost about $9,850 per patient annually. People living with HIV who are prescribed the drug will take two 400-milligram tablets daily in combination with other antiretrovirals chosen by their physicians, the San Francisco Chronicle reports. Robert Rode, marketing vice president at Merck, said the new pills should be available in as few as two weeks.
According to Rode, Merck has been providing raltegravir at no cost to 6,000 people worldwide -- including 3,400 in the U.S. -- while it waited for FDA marketing approval. He added that the company has a program in place to "make this product available globally". Merck has promised to study the drug for at least five years to monitor any side effects that might not have appeared in initial clinical trials, Reuters reports.
Source: Kaiser Family Foundation