For the first time, the federal government has issued guidelines on attempting to avoid HIV infection after accidental exposure to the virus outside of the health care workplace.
The Centers for Disease Control and Prevention-issued guidelines call for a 28-day course of a three-drug regimen of highly active antiretroviral therapy, but only if a high-risk exposure occurred within 72 hours of treatment initiation (MMWR 2005;54[RR02]:1–20).
The guidelines define high-risk exposures as those that occur through unprotected sex, condom breakage or slippage, sexual assault, the sharing of injection-drug equipment, or an accident with a source known to be HIV-infected.
If the HIV status of the source is unknown, physicians and patients should make decisions on nonoccupational postexposure prophylaxis (nPEP) on a case-by-case basis, taking into account the specific circumstances of the possible exposure and the risk of infection.
NPEP is not recommended for negligible exposure risks or for exposures that occurred more than 72 hours prior to treatment.
Prophylaxis is also not recommended for people whose behaviors result in frequent, recurrent exposures to HIV, such as those who often have unprotected sex with HIV-infected partners, or injection drug users who often share equipment.
NPEP is intended to be a “safety net,” similar to the prophylaxis that has long been available to health care workers and others who have been exposed to HIV in an occupational setting, Ronald O. Valdiserri, M.D., said during a press teleconference sponsored by the Centers for Disease Control and Prevention.
“It is clearly not a morning-after pill,” he said, pointing out the exacting nature of the 28-day regimen and its potential side effects.
The CDC guidelines are supported by a number of studies, including a recent feasibility study of 700 patients who were evaluated 12 weeks after nPEP was initiated. Of the 700, 7 individuals seroconverted, investigator Michelle Roland, M.D., reported.
Six of the seven seroconverters reported other high-risk encounters in the 6 months before nPEP; three of the seven reported ongoing high-risk behavior even after starting nPEP, suggesting that the failure of nPEP in these patients may not have been entirely due to medication failure.
Adherence to the treatment was fairly good, Dr. Roland said. During week 1, 84% of patients reported no missed doses during the prior 4 days; 78% reported no missed doses during week 2 and week 4.
While stating that no specific multidrug regimen has been shown to be superior to any other in the nPEP population, the guidelines list two preferred regimens and nine alternatives.
The drugs in the preferred nonnucleoside reverse transcriptase inhibitor (NNRTI)-based regimen are efavirenz plus either lamivudine or emtricitabine plus either zidovudine or tenofovir. Efavirenz should be avoided in pregnant women or women of childbearing potential.
The drugs in the preferred protease-inhibitor (PI)-based regimen are lopinavir and ritonavir (coformulated as Kaletra) plus zidovudine plus either lamivudine or emtricitabine.
The 28-day regimen will cost approximately $600–$1,000 depending on the specific drugs prescribed, according to Dr. Valdiserri, deputy director of CDC's National Center for HIV, STD, and TB Prevention.
The federal guidelines come well after some states—including California, Massachusetts, and Rhode Island—instituted their own nPEP guidelines. But Dr. Valdiserri rejected the notion that the federal government has been dragging its feet on issuing guidelines.
He noted that the CDC convened an expert panel in 1998, and the panel concluded that, at that time, there was insufficient evidence on the effectiveness of nPEP.
A second expert panel in 2001 did recommend nPEP based on new data from human and animal studies, but it has taken several more years for the guidelines to make their way through the bureaucracy.
The full set of recommendations, including dosages, side effects, and other prescribing information for 20 antiretroviral drugs and combination formulations, can be found at www.cdc.gov/mmwr/mmwr_rr.html
