On August 6, 2007, the U.S. Food and Drug Administration (FDA) approved Selzentry, a drug manufactured by Pfizer Inc., to help patients with the AIDS virus. The drug is intended for patients who are running out of options with current available treatments.

Selzentry, known chemically as maraviroc, is the first AIDS drug that works by blocking a CCR5 receptor, a crucial doorway the virus uses to enter white blood cells. Previous HIV drugs attacked the virus itself. The drug is expected to hit the market in September 2007.

In the past, researchers have found patients who lack a CCR5 doorway are somewhat resistant to HIV infections or are slow to develop AIDS if they do become infected. Approval of drugs used to block CCR5 receptors has been cautious, however, because of the side effects associated with this family of drugs.

Selzentry may cause liver damage (hepatoxicity), heart attacks or an increased risk of cancer. Other side effects include dizziness, upper respiratory infections and fever. The pill will come with a “black box” warning, the strongest available for prescription drugs, indicating a risk of serious injury or even death.

Dr. Debra Birnkrant, the FDA’s HIV drugs chief, said the benefits of the drug “clearly outweigh the risks.” But, she added, “That doesn’t mean there aren’t any risks.”

Selzentry will not be prescribed to newly-diagnosed HIV patients, but to patients whose virus is nearly resistant to today’s HIV drugs. Additionally, patients must have an HIV strain that uses the CCR5 pathway. The FDA estimates this will apply to about 50-60 percent of AIDS patients.

The twice-a-day pill would be used in addition to already prescribed HIV drugs, and will cost about $900 per month wholesale.

In a six-month study, patients who took Selzentry were twice as likely to see their virus levels reduced to the point that they were nearly unmeasurable.

In approving Selzentry, the FDA cited a need for additional treatment options for hard-to-treat patients. Nonetheless, the FDA is still requiring Pfizer to conduct additional research to assess long-term effects of the drug.

Source: Lauran Neergaard, “FDA approves novel drug AIDS patients,” Wral.com, August 6, 2007; “Pfizer wins U.S. approval for new HIV drug,” Reuters, August 6, 2007.