Tolerability of postexposure antiretroviral prophylaxis for occupational exposures to HIV

A substantial body of evidence provides support (but not definitive proof of efficacy) for the use of antiretroviral agents as postexposure prophylaxis for occupational exposures to HIV in the healthcare workplace. Despite the lack of definitive evidence of the efficacy of these agents in this setting, over the past decade this intervention has become the standard of care for healthcare workers who sustain occupational exposures to HIV. Administration of these agents--even for a relatively short 28-day postexposure course--is often fraught with difficulty. All of the agents currently used for postexposure prophylaxis regimens have substantial adverse effects, and significant adverse effects occur in more than two-thirds of individuals electing prophylaxis. This manuscript reiterates current US Federal Government guidelines for the administration of postexposure prophylaxis, specifically noting that zidovudine plus lamivudine (with or without a protease inhibitor) remains the recommended regimen. The paper summarises the significant toxicities associated with nucleoside reverse transcriptase inhibitors (primarily nausea, vomiting, diarrhoea and bone marrow suppression), non-nucleoside reverse transcriptase inhibitors (rash, fever, gastrointestinal symptoms and hepatitis, including hepatic decompensation necessitating liver transplantation) and protease inhibitors (nausea, vomiting, diarrhoea, abdominal pain, hyperglycaemia, hyperlipidaemia, headache and anorexia). As a class, the antiretroviral agents have an extraordinary number of drug interactions. The non-nucleoside reverse transcriptase inhibitors and the protease inhibitors are metabolised through the cytochrome P450 pathway, and the effects of concomitant administration of protease inhibitors with other agents in the same class are discussed, as well as the effects of concomitant administration of protease inhibitors with non-nucleoside agents. The potential for numerous and medically risky drug interactions emphasises the importance of planning antiretroviral prophylaxis in consultation with practitioners or clinical pharmacists who are skilled in the use of these agents and knowledgeable about the potential for significant drug interactions that could either reduce the benefit of prophylaxis or increase the potential for toxicity. Another common problem encountered by individuals managing postexposure prophylaxis programmes relates to the administration of chemoprophylaxis to a pregnant healthcare worker who has sustained an occupational exposure to HIV. We address what is known about the potential for toxicity and emphasise the recently published warning concerning the deaths of pregnant women and their offspring from lactic acidosis while receiving regimens containing stavudine and didanosine.