Praziquantel is an anthelmintic 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 and subsequently for clonorchiasis. 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. The dose for treating clonorchiasis is 25 mg/kg 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. Serious adverse events include transient clinical deterioration, cardiac arrhythmias, hypersensitivity reactions and rash.
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 been rarely associated with clinically apparent liver injury, which generally accompanied hypersensitivity reactions such as rash and fever. In a large retrospective survey from China, 2 of 25,000 treated patients were reported to have developed jaundice after praziquantel therapy, 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 strategies 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. Thus, mild acute liver injury can accompany systemic hypersensitivity reactions to praziquantel, but both the allergic reaction and the liver injury tend to be short-lived and resolve rapidly even without specific therapy.
Likelihood score: D (possible rare cause of clinically apparent liver injury usually as a part of a systemic hypersensitivity reaction).