Also known as maraviroc, the drug is the first in a new class of oral HIV medicines. While older AIDS drugs keep the HIV virus from entering healthy immune cells, Selzentry is the first drug designed to target the virus itself.
The medicine is the first in a new class that blocks the CCR5 receptor, a chemical portal used by HIV to get into healthy cells. The drug changes the shape of the entryway, making it impossible for HIV to get in.
The U.S. Food and Drug Administration has approved Selzentry for use in patients who have tried other medicines and for those for whom a diagnostic test has confirmed that their HIV strain is linked to the CCR5 receptor. About 50 percent to 60 percent of patients who have been treated with other AIDS drugs meet that definition, says the FDA.
Patients will have to get a test, available from Monogram Biosciences Inc. of South San Francisco, California, to determine whether the drug could target their type of HIV. The test, called Trofile, is 90 percent accurate.
Meanwhile, the FDA informs that Selzentry will come with a "black box" warning, the strongest for prescription drugs, about the risk of liver toxicity.
The drug's label also will mention the possibility of heart attacks under a list of warnings and precautions, the agency added.
Till date, the most common problems reported in studies of patients who took Selzentry include cough, fever, upper respiratory tract infections, rash, abdominal pain and dizziness.
An elated Pfizer expects Selzentry to be available next month.
From study results by the company, it was seen that about 45 percent of patients who took maraviroc had their HIV virus suppressed to undetectable levels. The same was true for 23 percent who got a placebo. All patients also were treated with a cocktail of the best available drugs and had tried other regimens.
Selzentry's safety and effectiveness has not been established in adults or children who have never been treated with other HIV drugs, the FDA says, nor in pregnant women.
The move has sent Pfizer shares to their biggest gain, more than a year. Analysts say it may generate $145 million in sales next year. The drug will cost about $900 a month wholesale, comparable to other HIV treatments, Pfizer said.
``This is an important new product for many HIV-infected patients who have not responded to other treatments and have few options,'' says Steven Galson, the director of the FDA's Center for Drug Evaluation and Research.
Maraviroc will be given to patients as an oral pill to be taken twice a day.