Chapter 5 - Drug Interactions with Antimicrobial Agents

Abstract

This chapter presents antibacterial, antifungal, and antiviral agents combinations and their interaction. The variety of chemical families represented as having antibacterial, antifungal, or antiviral activities are legion. The antifungal agents are amphotericin, flucytosine, griseofulvin, nystatin, and terbinafine. The combination of flucytosine/amphotericin interaction is mutual potentiation of antifungal action. The combination of Rifampicin/flucytosine interaction is the rifampicin increase in the rate of metabolism, and flucytosine reduces its efficacy. The antiviral agents are acyclovir, amantadine hydrochloride, famciclovir, foscarnet sodium, zidovudine, and ganciclovir. Foscarnet can produce renal damage, in some cases so serious that the patients have required dialysis. The most common side-effects of ganciclovir are hematalogical and include neutropoenia and thrombocytopenia. Some degree of neutropenia occurs in 40% of patients treated. The manufacturer recommends that ganciclovir should not be used with dapsone, pentamidine, flucytosine, vincristine, vinblastine, and adriamycin. Zidovudine should be used with caution with any agent, which is potentially nephrotoxic, such as pentamidine, dapsone, amphotericin, fluocytosine, ganciclovir, interferon, vincristine, vinblastine, and doxorubicin. Experience of drug interaction potential is limited, but the manufacturer warns that phenytoin blood levels should be monitored because reports are contradictory in most of the cases studied.