Background: Giardia duodenalis is the most commonly detected parasite in the intestinal tract of humans and 5-nitroimidazole compounds, quinacrine and furazolidone have been used against giardiasis. However, cases refractory to treatment with these drugs are becoming more common worldwide.
Objective: To compare the efficacy and safety of mebendazole versus tinidazole in the treatment of giardiasis.
Research design and methods: 122 children (aged 5 to 15 years) of both sexes with confirmed Giardia duodenalis cysts or trophozoites in their stool samples were randomly separated into two groups of 61 individuals. Each group received either mebendazole 200 mg three times for 1 day or tinidazole 50 mg/kg in a single dose. The evaluation of the efficacy was based on parasitological response. Parents or legal guardians of each child were asked to provide three fecal samples on days 3, 5, and 7 after treatment completion. A child was considered to be cured if no Giardia trophozoites or cysts were found in any of the three post-treatment fecal specimens evaluated by direct wet mounts and/or after Ritchie concentration techniques.
Results: The frequency of cure was higher for tinidazole (81.97%) than for mebendazole (63.93%); the difference was statistically significant (p < 0.05). Transient abdominal pain was more common in children treated with mebendazole (p < 0.05), whereas loss of appetite, bitter taste, headache, vomiting, and nausea were more common in the tinidazole-treated group (p < 0.05).
Conclusions: Three doses of mebendazole, in a single day, are inferior to a single dose tinidazole in the treatment of giardiasis.