Clinical study evaluating efficacy of praziquantel in clonorchiasis.

In 74 patients with clonorchiasis, the efficacy and safety of praziquantel was evaluated in a two-phase study: a double-blind, randomized controlled trial of praziquantel versus placebo (42 patients) and an open study (32 patients). All but one of the patients were Laotians. The intensity of clonorchiasis was light in 85% (63 of 74) and moderate in 15% (11 of 74) of the patients. Cure based on our established criteria was noted in 67 of 67 patients (100%) treated with praziquantel at a dose of 75 mg/kg per day. In contrast, four patients (20%) in the placebo group, each with light infection, ceased passing eggs and were, according to our established protocol, considered spontaneous cures (P less than 0.0001). Adverse effects of praziquantel were transient and included nausea and vomiting (15%), vertigo (12%), hepatomegaly (4.5%), headache (1.5%), rash (1.5%), and hypotension (1.5%). Of 20 patients who received placebo, 1 (5%) developed transient skin rash, fever, and chills. Clinically minor and transient, but statistically significant, changes in hemoglobin, total protein in serum, and levels of uric acid, cholesterol, and bilirubin in serum were noted. Results of this study showed that praziquantel is safe, well tolerated, and effective and should be considered as the drug of choice for treatment of clonorchiasis. In moderate infections, a second course of praziquantel therapy may be necessary to eliminate infection.