Drug Interaction Report

MONITOR: Coadministration with inducers or mixed inducer/inhibitors of certain metabolic pathways may produce clinically meaningful reductions in the plasma concentrations of caspofungin. This assumption is based on results from regression analyses of patient pharmacokinetic data derived from a small number of patients who were administered the drugs efavirenz, nelfinavir, nevirapine, phenytoin, rifampin, dexamethasone, or carbamazepine prior to and/or concurrently with caspofungin. There are no data from formal drug interaction studies to evaluate these regression analyses, and it is not known which metabolic pathway involved in caspofungin clearance may be inducible.

MANAGEMENT: Caspofungin product labeling recommends that during coadministration with efavirenz, nelfinavir, nevirapine, phenytoin, rifampin, dexamethasone or carbamazepine, an increase in the daily dosage to 70 mg (following the usual 70 mg loading dose) should be considered in patients who are not clinically responding. While data are lacking for other drugs that are known to induce hepatic enzymes, the possibility of a similar interaction should be considered.

MONITOR: Isolated case reports have suggested that the ingestion of alcohol during griseofulvin therapy may rarely cause disulfiram-like reactions, flushing, tachycardia, or increased effects of alcohol. The mechanism is unknown.

MANAGEMENT: Patients should be advised of the possibility of increased adverse effects or a disulfiram-like reaction.

The recommended maximum number of medicines in the 'antifungal agents' category to be taken concurrently is usually one. Your list includes two medicines belonging to the 'antifungal agents' category:

• caspofungin
• Grisactin 500 (griseofulvin)

Note: In certain circumstances, the benefits of taking this combination of drugs may outweigh any risks. Always consult your healthcare provider before making changes to your medications or dosage.