Praziquantel Rifampicin

Clinically important, potentially hazardous interactions with albendazole, aminoglutethimide, aspirin, bexarotene, carbamazepine, cyclophosphamide, dasatinib, diuretics, ephedrine, imatinib, itraconazole, lapatinib, live vaccines, lopinavir, methotrexate, phenobarbital, phenytoin, praziquantel, primidone, rifampicin, rifampin, temsirolimus, warfarin... 

The plasma levels of praziquantel were markedly reduced by rifampicin pretreatment, to undetectable levels in over half of the subjects in one study. It is predicted that rifampicin will reduce the efficacy of praziquantel. 

Pretreatment with rifampicin 600 mg once daily for 5 days markedly reduced the AUC and maximum level of a single 40-mg/kg dose of praziquantel in 10 subjects. Seven of the subjects had undetectable praziquantel levels (less than 12.5 nanograms/mL), and the other 3 had an 85% reduction in the AUC of praziquantel. The same subjects were then given three doses of praziquantel 25 mg/kg at intervals of 8 hours, alone, and after pretreatment with rifampicin. In this multiple-dose study, 5 of the 10 subjects had undetectable praziquantel levels, and the remainder had an 80% reduction in AUC. It was suggested that rifampicin induced the metabolism of praziquantel via cytochrome P450 isoenzyme CYP3A4. Although efficacy has not been assessed, the authors concluded that the levels of praziquantel after rifampicin pretreatment were less than those considered necessary for anthelmintic activity. They therefore recommend that the combination should be avoided, a stance which is also taken by one of the manufacturers of praziquantel. ... 

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