Drug interactions between efavirenz and itraconazole

9 February 2009. Related: PK and drug interactions.

This is a case report of the interaction between itraconazole and efavirenz in a woman with disseminated histoplasmosis and HIV-1 infection.

Previous data in healthy volunteers have shown a decrease of about 40% in exposure of itraconazole and its active metabolite (hydroxyitraconazole) and a recommendation to consider alternative antifungal treatment. Here the authors recommend that by the use of therapeutic drug monitoring of both efavirenz and itraconazole individual optimization of dosage can be made so that a change in therapy is not necessary. In this case the patient had a good clinical response and obtained therapeutic concentrations with a regimen including efavirenz 400 mg once daily and itraconazole 800 mg once daily.

Reference:

Huet E et al. Therapeutic monitoring is necessary for the association itraconazole and efavirenz in a patient with AIDS and disseminated histoplasmosis. AIDS, 2008, 22(14): 1885-1886.
http://www.hiv-druginteractions.org/frames.asp?new/Content.asp?ID=403

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