Indinavir: a review of its use in the management of HIV infection.

Abstract

Indinavir is a protease inhibitor used in the treatment of patients with HIV infection. Combination antiretroviral therapy with indinavir plus 2 nucleoside reverse transcriptase inhibitors (NRTIs) is associated with greater reductions in viral load, greater increases in CD4+ cell counts, and reduced morbidity and mortality when compared with 2 NRTIs alone. In the landmark clinical trial ACTG 320, the rate of progression to AIDS or death (primary end-point) among zidovudine-experienced patients treated with indinavir, zidovudine and lamivudine was approximately half that of patients who received only zidovudine plus lamivudine (6 vs 11%; p < 0.001). The durability of an indinavir-containing regimen was demonstrated in Merck protocol 035, an ongoing trial in which a significant proportion of patients had sustained viral suppression for up to 3 years. Merck protocol 039, also an ongoing trial, showed a greater effect on surrogate markers of HIV disease progression with indinavir-based triple therapy than with zidovudine plus lamivudine or indinavir monotherapy in patients with advanced disease (median baseline CD4+ count 15 cells/microL). Numerous additional clinical trials have established the beneficial antiviral and immunological effects of indinavir in both antiretroviral-naive and -experienced patients with HIV infection. Indinavir is associated with various drug class-related adverse events, including gastrointestinal disturbances (e.g. nausea, diarrhoea), headache and asthenia/fatigue. A lipodystrophy syndrome has been commonly reported with indinavir and other protease inhibitors combined with NRTIs, but it has also been reported in many protease inhibitor-naive patients, and a definitive causal link has not been established between the syndrome and protease inhibitors. Nephrolithiasis may develop in about 9% of patients receiving indinavir but does not appear to be associated with other protease inhibitors; <0.5% of patients receiving indinavir discontinue the drug because of nephrolithiasis, which may be the extreme end of a continuum of crystal-related renal syndromes. Additional renal problems (e.g. nephropathy) have been reported in small numbers of patients receiving indinavir. In summary, indinavir is a protease inhibitor with well documented efficacy when used as part of combined therapy in patients with HIV infection. Both US and UK treatment guidelines continue to recommend protease inhibitor-based regimens including indinavir as a first-line option. Indinavir is being studied as a twice daily and once daily regimen with a low dosage of ritonavir as a way to alleviate tolerability, drug interaction and patient compliance/adherence issues. Indinavir-containing triple therapy has demonstrated positive effects not only on surrogate markers of disease progression, but also on clinical end-points of mortality and morbidity in patients with HIV disease. Protease inhibitors are a significant advance in the care of patients with HIV infection, and, in an era of evidence-based medicine, indinavir represents an important component of antiretroviral treatment strategies.