The US Food and Drug Administration (FDA) announced yesterday it has approved Pfizer’s new antiretroviral drug, maraviroc (brand name Selzentry), for use in adults with HIV, the virus that causes AIDS. The approval is for adults who have not responded to other HIV treatments.
Maraviroc is a new type of drug designed to slow the progress of HIV and was fast tracked for review by the FDA. Experts said that this offers a new alternative to the thousand of Americans who need a new treatment for HIV.
The drug should be on sale next month said New York based Pfizer in a prepared statement.
The FDA has approved the drug for use in combination with other antiretrovirals for patients who have CCR5-tropic HIV-1, have already been treated with other HIV drugs, and who show high levels of HIV in their blood (who have a “high viral load”). The drug will be in oral form, to be taken twice a day, said a Pfizer spokesperson according to Bloomberg yesterday.
Unlike many HIV drugs that fight HIV from inside infected white blood cells, maraviroc works by blocking entry to uninfected cells via one of HIV’s preferred access points, the CCR5 co-receptor, which normally binds to proteins and other ligands of the immune system.
About 50 to 60 per cent of patients who have already been on other antiretrovirals have HIV strains that use the CCR5 co-receptor as a penetration route to uninfected white cells.
Dr Steven Galson, director of FDA’s Center for Drug Evaluation and Research said that:
“This is an important new product for many HIV-infected patients who have not responded to other treatments and have few options.”
The drug carries a boxed warning about possible liver toxicity (hepatoxicity), and there is also a reference to heart attack risk in the Warnings and Precautions section.
The FDA reviewed the data from two double-blind, placebo controlled trials covering over 1,000 patients who had been treated with other HIV drugs and tested for evidence of CCR5 tropic HIV-1 in their blood before being given maraviroc.
The FDA pointed out that maraviroc’s safety and effectiveness has not been proved in adults and children who have never been treated with anti HIV drugs before, and neither has it been tested on pregnant women.
The FDA advises HIV positive women not to breastfeed, whether they are using antiretrovirals or not.
Side effects of maraviroc include cough, fever, musculoskeletal symptoms, infections of the upper respiratory tract, rash, pain in the abdominal area, and dizziness.
Written by: Catharine Paddock