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.