Studies in vitro show that caspofungin acetate is not an inhibitor of any enzyme in the cytochrome P450
(CYP) system. In clinical studies, caspofungin did not induce the CYP3A4 metabolism of other drugs. Cancidas is
not a substrate for P-glycoprotein and is a poor substrate for cytochrome P450 enzymes.
Clinical studies in healthy volunteers show that the pharmacokinetics of CANCIDAS are not altered by itraconazole,
amphotericin B, mycophenolate, nelfinavir, or tacrolimus. CANCIDAS has no effect on the pharmacokinetics of
itraconazole, amphotericin B, or the active metabolite of mycophenolate.
CANCIDAS reduced the blood AUC0-12 of tacrolimus (FK-506, PrografÒ3) by approximately 20%, peak blood concentration (Cmax) by 16%, and
12-hour blood concentration (C12hr) by 26% in healthy subjects when tacrolimus (2 doses of 0.1 mg/kg 12
hours apart) was administered on the 10th day of CANCIDAS 70 mg daily, as compared to results from a control period
in which tacrolimus was administered alone. For patients receiving both therapies, standard monitoring of tacrolimus
blood concentrations and appropriate tacrolimus dosage adjustments are recommended.
In two clinical studies, cyclosporine (one 4 mg/kg dose or two 3 mg/kg doses) increased the AUC of caspofungin by
approximately 35%. CANCIDAS did not increase the plasma levels of cyclosporine. There were transient increases in
liver ALT and AST when CANCIDAS and cyclosporine were co-administered.
A drug-drug interaction study with rifampin in healthy volunteers has shown a 30% decrease in caspofungin trough
concentrations. Patients on rifampin should receive 70 mg of CANCIDAS daily. In addition, results from regression
analyses of patient pharmacokinetic data suggest that co-administration of other inducers of drug clearance
(efavirenz, nevirapine, phenytoin, dexamethasone, or carbamazepine) with CANCIDAS may result in clinically meaningful
reductions in caspofungin concentrations. It is not known which drug clearance mechanism involved in caspofungin
disposition may be inducible. When CANCIDAS is co-administered with inducers of drug clearance, such as efavirenz,
nevirapine, phenytoin, dexamethasone, or carbamazepine, use of a daily dose of 70 mg of CANCIDAS should be