Zalcitabine Dapsone

This drug is used cautiously in patients with peripheral vascular disease, neuropathy, chronic pancreatitis, or impaired liver function. Didanosine is a Pregnancy Category B drug and is used cautiously during pregnancy and lactation. There may be a decrease in the effectiveness of dapsone in preventing Pneumocystis carinii pneumonia when didanosine is administered with dapsone Use of didanosine with zalcitabine may cause additive neuropathy. Absorption of didanosine is decreased when it is administered with food. 

Drugs that may interact with zalcitabine include antacids, chloramphenicol, cisplatin, dapsone, didanosine, disulfiram, ethionamide, glutethimide, gold, hydralazine, iodoquinol, isoniazid, metronidazole, nitrofurantoin, phenytoin, ribavirin, vincristine, cimetidine, metoclopramide, amphotericin, aminoglycosides, foscarnet, antiretroviral nucleoside analogs, pentamidine, and probenecid. 

Buffering agents that are compounded with didanosine to counteract its degradation by gastric acid may interfere with the absorption of other drugs that require acidity (e.g., indinavir, delavirdine, ketoconazole, fluoroquinolones, tetracyclines, dapsone). An enteric-coated formulation Videx EC) that dissolves in the basic pH of the small intestine is not susceptible to these interactions. Ganciclovir and valganciclovir can increase blood levels of didanosine. The use of zalcitabine with didanosine is not recommended because that combination carries an additive risk of peripheral neuropathy. The combination of didanosine with stavudine increases the risk of pancreatitis, hepatotoxicity, and peripheral neuropa-... 

Other neurotoxic substances (isoniazid, metronidazole, dapsone, vincristine, pyridoxine, stavidine, zalcitabine, and others)... 

A pharmacokinetic study in 12 TUV-positive patients who were given zalcitabine 1.5 mg three times daily and dapsone 100 mg daily, alone or together, found that dapsone did not significantly affect the kinetics of the zalcitabine. However, zaleitabine deeieased the clearance of dapsone by 21%, increased its maximum serum levels by 19% and increased its half-life by 34%. These changes are relatively small and seem unlikely to have much clinical relevance, but until this is confirmed it would seem prudent to monitor the concurrent use of these two drugs. The UK manufacturer recommended caution with the combination because of the possibility of an increased risk of peripheral neuropathy the US manufacturer advised avoiding the combination where possible. ... 

Lee BL, Tauber MG, Chambers HF, Gamberto io J, Delahunty T. Zalcitabine (DDC) and dapsone (DAP) pharmacokinetic (PK) interaction in HIV-infected patients. Clin Pharmacol Ther (199 57, 186. 

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