Concomitant administration of drugs that increase the activity of drug metabolizing liver enzymes (Cytochrome P450), e.g. antiepileptic drugs (phenytoin, phenobarbital and carbamazepine), dexamethasone, may reduce plasma levels of praziquantel.
Concomitant administration of rifampin should be avoided (see WARNINGS).
Concomitant administration of drugs that decrease the activity of drug metabolizing liver enzymes (Cytochrome P 450), e.g. cimetidine, ketoconazole, itraconazole, erythromycin may increase plasma levels of praziquantel.
Chloroquine, when taken simultaneously, may lead to lower concentrations of praziquantel in blood. The mechanism of this drug-drug interaction is unclear.
Grapefruit juice was reported to produce a 1.6-fold increase in the Cmax and a 1.9-fold increase in the AUC of praziquantel. However, the effect of this exposure increase on the therapeutic effect and safety of praziquantel has not been systematically evaluated.