Praziquantel is an antihelmintic agent with activity against a broad spectrum of trematodes and cestodes that is used predominantly in the therapy of schistosomiasis, liver flukes, and cysticercosis. Praziquantel therapy has been reported to cause serum aminotransferase elevations during therapy, but clinically apparent liver injury after its use is rare if it occurs at all.
Praziquantel (praz" i kown' tel) is a heterocyclic prazino-isoquinoline derivative with a broad spectrum of activity against several trematodes (Fasciola, Schistosoma) and cestodes (Taenia). Praziquantel is believed to act by interference with tegument calcium transport, resulting in paralysis of the parasitic worms with subsequent loss of adherence to tissue, degradation and expulsion. Praziquantel was approved for use in the United States in 1982 for schistosomiasis. Praziquantel is also commonly used in veterinary medicine. Praziquantel is available for human use in tablets of 600 mg generically and under the brand name Biltricide. The typical dose for treating schistosomiasis in adults is 20 mg/kg (depending upon the species) three times over one day. Side effects are common but transient, and include abdominal discomfort, nausea, vomiting, vertigo, muscle aches, drowsiness, headaches and fatigue, some of the symptoms being due to its effects on the parasites.
Praziquantel therapy has been associated with elevations in serum aminotransferase levels in up to 27% of patients, but these abnormalities were self-limiting. Praziquantel has not been associated with clinically apparent liver injury. In a large retrospective survey from China, 2 of 25,000 treated patients were reported to have developed jaundice, but no specific information about the two cases was provided. There have been few studies of long term therapy with praziquantel, and most controlled trials of this agent have used one day courses without serum aminotransferase monitoring. However, millions of people have been treated with praziquantel as a part of large scale control stategies in China where schistosomiasis Japonica is endemic. The combination of praziquantel preventive therapy and snail control has resulted in marked decreases in the prevalence of infection in the population with no evidence of significant toxicity.
Mechanism of Injury
Praziquantel is extensively metabolized by the liver via the cytochrome P450 system and might cause hepatic injury as a result of a toxic intermediate of its metabolism. Plasma levels of praziquantel are affected by inducers (rifampin decreases drug levels) and inhibitors of P450 activity (cimetidine, ketaconazole and erythromycin can reduce drug levels).
Outcome and Management
Praziquantel is usually well tolerated and clinically apparent liver injury due to its use must be very rare if it occurs at all.
REPRESENTATIVE TRADE NAMES
Praziquantel – Biltricide®
Product labeling at DailyMed, National Library of Medicine, NIH
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References updated: 22 January 2014
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Ferrajolo C, Capuano A, Verhamme KM, Schuemie M, Rossi F, Stricker BH, Sturkenboom MC. Drug-induced hepatic injury in children: a case/non-case study of suspected adverse drug reactions in VigiBase. Br J Clin Pharmacol 2010; 70: 721-8. PubMed Citation (World wide pharmacovigilance database contained 9036 hepatic adverse drug reactions in children, there were no antihelmintic agents listed among the top 40 implicated medications).
Drugs for parasitic infections. Treat Guidelines Med Ltr 2010; 8: 31-20. Not in PubMed. (Brief description of drugs for parasitic infections in adults and children as well as a table of their major side effects; praziquantel is the drug of choice for schistosomiasis, liver flukes (Clonorchis sinesis and others), and intestinal tapeworm; side effects can include abdominal pain, diarrhea, fatigue, nausea, drowsiness, fever and rash).
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strategies in China. Parasitol Res 2013; 112: 909-15. PubMed Citation (Summary of results of approaches to decreasing schistosomiasis japonica infection in China with discussion of success and safety of praziquantel prophylaxis in the general population; no mention of hepatotoxicity).
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