Designing salvage antiretroviral regimens. Some basic guidelines and use of resistance testing

Treatment of HIV infection is rapidly changing from a hit-or-miss hodgepodge of unknowns, in which nearly anything beneficial was acceptable, to a true science based on reproducible principles. With this growth in complexity, HIV therapy has become a valid field of medicine. The potency of available agents, their success in suppressing the destructive nature of HIV infection, and the increasingly rapid pace of technology development in this area require that HIV-seropositive patients be treated by physicians specializing in the field. The growing but finite number of antiretroviral therapeutic agents demands that a thoughtful, strategic, long-term approach be formulated. The evolving science of antiretroviral resistance testing offers great promise for better shaping this approach, which is still less than straightforward. Potential interactions, some good and some bad, between mutations within HIV genes will profoundly affect therapy and are still to be defined. Declaring that a regimen has failed and choosing a new one to replace it is a complex task, particularly when all the factors involved are considered (e.g., rising viral load, declining CD4 count, patient adherence, patient preferences, drug interactions, adverse effects). Care of HIV-positive patients has always been an art, and now at last it is becoming a science.