Zalcitabine Rifabutin

Ritonavir exhibits additive to synergistic effects against HIV when used in combination with reverse-transcriptase inhibitors such as zidovudine or zalcitabine. Ritonavir pro-dnces a large increase in the plasma concentration of amio-darone, astemizole, bepridil, bupropion, cisapride, clozapine, encainide, flecainide, meperidine, peroxicam, propafenone, propoxyphene, quinidine, rifabutin, and terfenadine. 

Items 6-7 A patient with AIDS has a CD4 count of 45/ xL. He is being maintained on a three-drug regimen of indinavir, zalcitabine, and zidovudine. For prophylaxis against opportunistic infections, he is also receiving cidofovir, fluconazole, rifabutin, and trimethoprim-sulfamethoxazole. 

Didanosine, stavudine and zalcitabine are not expected to interact with rifabutin, but rifabutin may modestly increase the clearance of zidovudine. An isolated case describes undetectable rifabutin levels in a patient taking antiretrovirals including buffered didanosine. 

The UK manufacturer of rifabutin suggests that no significant interaction would be expected between rifabutin and zalcitabine. ... 

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