Author(s): Andrade RA, Evans RT, Hamill RJ, Zerai T, Giordano TP
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Abstract BACKGROUND: Itraconazole is the preferred drug for chronic maintenance therapy in HIV-infected patients with disseminated histoplasmosis. Unfortunately, few clinical data exist confirming a presumed interaction between itraconazole and nonnucleoside reverse transcriptase inhibitors (NNRTIs). OBJECTIVE: To determine whether serum itraconazole concentrations are affected by the type of antiretroviral therapy (NNRTI or protease inhibitor [PI]) being taken concomitantly. METHODS: This retrospective cohort identified patients on antiretroviral therapy and itraconazole for disseminated histoplasmosis between January 2003 and December 2006 at a large HIV clinic in Houston, TX. Available laboratory values were abstracted from medical records. RESULTS: Thirteen itraconazole concentrations from 10 patients were available for analysis: 7 patients were on concomitant PIs, 4 on concomitant NNRTIs, and 2 on antiretroviral regimens containing both PIs and NNRTIs. Six of the itraconazole concentrations during concomitant PI treatment were therapeutic (>1.0 microg/mL), in contrast with none in patients taking an NNRTI. All patients taking concomitant NNRTIs had undetectable serum itraconazole concentrations (<0.05 microg/mL). Two patients switched from NNRTI-based to PI-based antiretroviral regimens and subsequently reached therapeutic itraconazole concentrations. Although limited by small sample size, this study provides the largest clinical data among HIV-infected patients demonstrating that coadministration of an NNRTI and itraconazole results in significant decreases in itraconazole blood concentrations, likely by inducing the CYP3A4 enzyme system. CONCLUSIONS: Itraconazole concentrations should be monitored in patients taking concomitant NNRTIs. PI-based highly active antiretroviral therapy (HAART) may be preferred over NNRTI-based HAART when itraconazole is used to treat HIV-infected patients with disseminated histoplasmosis.
This article was published in Ann Pharmacother
and referenced in Journal of AIDS & Clinical Research