A variety of situations, either accidental or linked to high-risk behaviour, raise concerns about potential
infection from contact with the blood or genital secretions of a person who may be HIV-infected. Antiretroviral post-exposure prophylaxis is offered to prevent establishment of
HIV infection. As of 2011, what is the evidence for the efficacy of antiretroviral post-exposure prophylaxis? Under what circumstances is this treatment justified? To answer these questions, we reviewed the available evidence, based on the standard Prescrire methodology. The evidence for the efficacy of rapidly initiated prophylaxis following exposure comes mainly from one case-control study on health professionals injured while treating HIV-positive patients. Treatment with
zidovudine for 3 to 4 weeks was associated with a risk of
HIV seroconversion that was 5 times lower than among those not treated. The main clinical practice guidelines recommend the use of antiretroviral treatments that are already well established for chronic
HIV infection as post-exposure prophylaxis. A typical regimen combines
HIV-protease inhibitors (ideally
lopinavir +
ritonavir) with a fixed-dose combination of two
nucleoside (or
nucleotide)
reverse transcriptase inhibitors (
emtricitabine +
tenofovir or
lamivudine +
zidovudine). Certain antiretrovirals are best avoided as first-choice
therapy due to their adverse effects:
abacavir due to the risk of serious
allergic reactions;
atazanavir due to the risk of
jaundice and
torsades de pointes. Non-
nucleoside reverse transcriptase inhibitors (such as
efavirenz) frequently cause adverse cutaneous and neurosensory adverse effects, especially during the first weeks of treatment. The main adverse effects of antiretrovirals are gastrointestinal. Diarrhoea is common with
lopinavir. Antiretrovirals interact with many other drugs.
HIV-protease inhibitors reduce the efficacy of hormonal
contraceptives. The Iopinavir +
ritonavir +
zidovudine +
lamivudine combination has been used for a long time to treat pregnant women. No evidence of teratogenicity has been shown.The antiretrovirals
atazanavir,
emtricitabine,
nelfinavir,
nevirapine and
tenofovir can also be used but there is less experience with their use during pregnancy. Post-exposure treatment should be started as soon as possible: wash and rinse the
wound; initiate antiretroviral
therapy within 48 to 72 hours, without waiting to obtain all the information required for risk assessment; reassess the
infection risk 2 to 4 days later. Risk assessment should be based on the type and circumstances of exposure, and the source person's serological HIV status and viral load if the individual is known to be HIV-infected and receiving treatment.This information should be obtained urgently or estimated on the basis of
HIV infection is still possible despite post-exposure prophylaxis.Therefore, in order to avoid transmitting the virus to others, anyone exposed and potentially infected should be advised against unprotected sex or blood donation for 3 months, until serological evidence has been obtained that they have not been infected. In practice, the many situations in which the risk of
infection is uncertain should be managed on a case-by-case basis, with the patient's involvement, weighing the probability of HIV transmission against the adverse effects of a one-month course of antiretroviral
therapy.