Praziquantel Phenobarbital

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... 

Inducers of hepatic CYPs such as carbamazepine and phenobarbital reduce the bioavaUabihty of praziquantel. Dexamethasone reduces the bioavailability of praziquantel, but the mechanism is not understood. Under certain conditions, praziquantel may increase the bioavailability of albendazole. 

A patient with neuroeysticercosis taking phenytoin and phenobarbital for a seizure disorder had no response to praziquantel (four courses in doses of up to 50 mg/kg daily). Praziquantel 50 m g daily and dexamethasone 12 mg daily were started and, after one week, cimetidine 400 mg four times daily was added. The patient s serum praziquantel levels more than doubled with the addition of cimetidine (maximum serum levels raised from 350 to 826 nanograms/mL) and the AUC rose about fourfold, and became similar to that found in control subjects taking praziquantel alone. The patient showed marginal improvement, and continued to slowly improve over the following 4 months. ... 

Phen 4oin, phenobarbital and carbamazepine markedly reduce the serum levels of praziquantel, but whether this results in neu-rocysticercosis treatment failures is unclear. A case report suggests that the addition of cimetidine , (p.236) may control this interaction. 

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