Emtricitabine-tenofovir disoproxil fumarate (Truvada), a combination of two nucleoside analog HIV-1 reverse transcriptase inhibitors, has been approved by the Food and Drug Administration (FDA) as the first drug to be used to prevent HIV infection. Truvada was previously approved to treat HIV infection. Clinical trials of uninfected individuals who engage in sexual activity with one or more HIV-infected partners have shown that Truvada effectively reduces the risk of becoming HIV infected. This use of the drug is termed preexposure prophylaxis. According to the FDA label, other factors that place a person at high risk for contracting HIV and make her or him a candidate for prophylaxis with Truvada include engaging in sexual activity within a high-prevalence area or social network and one or more of the following:

* inconsistent or no condom use

* diagnosis of sexually transmitted infections

* exchange of sex for commodities (such as money, food, shelter, or drugs)

* use of illicit drugs or alcohol dependence

* incarceration

* a partner (or partners) of unknown HIV-1 status with any of the factors listed above

The drug should be used as part of a multifaceted approach to preventing HIV transmission, which should include safe sex practices, risk reduction counseling, and regular HIV testing. The Centers for Disease Control and Prevention (CDC) estimates that "only one-quarter of Americans with HIV currently have their virus suppressed to the levels needed to maintain their own health and prevent transmission to others" (read the CDC fact sheet on the use of Truvada for this indication at http://1.usa.gov/esua27). It further states that if preexposure prophylaxis is used "strategically and effectively, [it] could be cost-effective and may help reduce the continuing toll of HIV infection in this nation."

Truvada's label carries a boxed warning that there's a risk of drug resistance with use of Truvada for preexposure prophylaxis in the presence of undiagnosed HIV-1 infection. For this reason it's important that the patient's HIV status be determined prior to the initiation of prophylactic Truvada therapy. Patients with HIV shouldn't receive Truvada for this purpose. Patients who currently have, or within the last month have had, symptoms of an acute viral infection (fever, malaise, and body aches) may have been exposed to HIV. Initiation of drug therapy must be deferred for at least one month, when another HIV-1 test should be performed to confirm that the patient is HIV negative. Once therapy is started, patients need to be screened at least every three months to confirm that they remain HIV free. Additional boxed warnings on the label include the risk of lactic acidosis and severe hepatomegaly with steatosis (fatty liver), which could be fatal, and posttreatment acute exacerbation of hepatitis B. The label also warns that the drug can cause or worsen renal impairment, shouldn't be used with other drugs containing emtricitabine or tenofovir disoproxil fumarate, decreases bone mineral density, causes body fat redistribution or accumulation, and may produce immune reconstitution syndrome. The most common adverse effects of Truvada when used as HIV prophylaxis are headache, abdominal pain, and weight loss.

Because Truvada poses the risks of serious and potentially fatal adverse effects, the drug's manufacturer, Gilead, will provide training and education regarding safe use of the drug to providers prescribing Truvada for preexposure prophylaxis. Prescribers will be required to have patients sign an agreement prior to initiating HIV prophylaxis that informs them of safety risks and the importance of daily adherence to the drug regimen, frequent HIV-1 testing, and screening for sexually transmitted infections. The signed form will become part of the patient's permanent medical record.

Nurses who prescribe Truvada or work with patients taking it should confirm that they've received testing and are HIV negative. Nurses should also confirm that patients don't have hepatitis B or a creatinine clearance below 60 mL per minute. Nurses should instruct patients to take the drug once daily and not to take more than one dose at a time. Effectiveness of the prophylaxis is lost if the drug isn't taken daily. The importance of returning for follow-up testing every three months to confirm that a patient's HIV status remains negative should also be emphasized. To report suspected adverse reactions to Truvada, nurses can contact Gilead Sciences, at (800) 445-3235, or the FDA's MedWatch program, at (800) 332-1088 (FDA-1088) or http://www.fda.gov/medwatch.

To read the complete prescribing information, go to http://1.usa.gov/OF4q9w.