The Centers for Disease Control and Prevention has published a recommendation report on the use of antiretroviral drugs to prevent human immunodeficiency virus (HIV) infection after injection-drug use, sexual, and accidental exposure. “Antiretroviral Postexposure Prophylaxis After Sexual, Injection-Drug Use, or Other Nonoccupational Exposure to HIV in the United States” was released January 21, 2005, and is available online at http://www.cdc.gov/mmwr/mmwr_rr.html. The report summarizes information about the use of nonoccupational postexposure prophylaxis and lists guidelines for its use.

Recent data from human and animal studies, case reports, and documentation of the use of nonoccupational postexposure prophylaxis prompted the U.S. Department of Health and Human Services to update its recommendation for the use of nonoccupational postexposure prophylaxis in patients who seek treatment within 72 hours of high-risk exposure to a person known to be HIV positive.

According to the authors, when highly active antiretroviral therapy (HAART) is prescribed within 48 to 72 hours of nonoccupational exposure to HIV and continued for 28 days, the likelihood of transmission may be reduced. The earlier the nonoccupational postexposure prophylaxis is administered, the higher the chance that it will interrupt transmission.

The authors state that no specific antiretroviral medication or combination is optimal for nonoccupational postexposure prophylaxis. However, preferred regimens include efavirenz and lamivudine or emtricitabine with zidovudine or tenofovir (as a nonnucleoside-based regimen) and lopinavir and ritonavir (co-formulated in one tablet) and zidovudine with either lamivudine or emtricitabine. No evidence suggests that a three-drug HAART regimen is more effective than a two-drug regimen. When the source person is available for interview, his or her medication history and most recent viral load measurement should be considered when choosing medications for nonoccupational postexposure prophylaxis. This could help prevent prescription of medications to which the virus is already resistant.

According to the report, all patients seeking treatment after HIV exposure should be tested for antibodies at baseline, four to six weeks, three months, and six months. Patients should be informed about the signs and symptoms of acute retroviral infection and should be asked to return for evaluation if these occur. Physicians who provide nonoccupational postexposure prophylaxis also should monitor patients’ liver function, renal function, and hematologic parameters.

When a patient’s risk of transmission from contact is small or when more than 72 hours have passed since exposure, nonoccupational postexposure prophyl axis is not recommended. However, when a patient seeks treatment more than 72 hours after exposure, but the risk of virus transmission is severe, physicians may decide that the potential benefit of nonoccupational postexposure prophylaxis is greater than the potential risk of complications from antiretroviral therapy.