Management of HIV-infected patients with multidrug-resistant virus.

Treatment-experienced patients with HIV may harbor virus that has accumulated several mutations conferring decreased susceptibility to one or more antiretroviral drugs. For clinicians treating these patients, identifying a tolerable antiretroviral regimen with a reasonable chance of a durable virologic effect represents a major challenge. The first priority is to identify and correct the mechanisms responsible for previous treatment failure. Resistance testing and drug level monitoring may be useful in this setting. The patient's history of antiretroviral drug tolerability, comorbidities, and concomitant medications should be considered. Patients embarking on multiple-drug regimens will require close monitoring for adherence, toxicities, and drug-drug interactions. The guiding principle when constructing a rescue or salvage regimen is to achieve a cumulative activity score greater than 2, recognizing that some agents will have only partial activity. Some new drugs are available that may be helpful if used carefully with an active background regimen.