New safety data for the most commonly used drug to treat Chagas disease

The frequency of adverse reactions to benznidazole is high when treating chronic Chagas patients, although they were mostly mild effects, according to a study led by ISGlobal, an institution supported by the “la Caixa” Foundation, in collaboration with the Hospital Clinic of Barcelona. The results point to the need of finding drug combinations or dosages in order to maintain efficacy but decrease its toxicity.

Benznidazole is one of the two existing antiparasitic drugs for Chagas' disease treatment. However, it is a poorly tolerated drug and its use to treat chronic disease raises safety concerns. Knowledge about its toxicity profile is scarce and mostly based on post-marketing observational studies.

In order to provide a systemic evaluation of safety of benznidazole in chronically infected adults, the authors combined data from two prospective clinical trials performed in 2013 and 2016 at the Hospital Clinic of Barcelona, designed to assess the safety of the drug produced by ELEA Laboratories, Argentina. Adverse reactions were observed in 85 of the 99 participants, with an average of three adverse reactions per patient. Most adverse reactions (90%) were mild and appeared in the first month of treatment. The researchers also identified some unexpected adverse reactions that were not described previously, such as sleeping disorders and anxiety.

“These results confirm that, with the most widely used dosage and regimen, there is a high frequency of adverse reactions to benznidazole” says Maria Jesús Pinazo, ISGlobal researcher and study co-author. “Until we have something better, benznidazole will remain part of the treatment in the near future, so these results underline the urgent need to find ways to combine it with other drugs or use different dosages in order to achieve maximum efficacy with the minimum toxicity”, she adds.

About Chagas Disease

Chagas Disease is caused by the protozoan T. cruzi and is most frequently transmitted through an insect vector (the kissing bug). However, transmission from mother to child or through blood or organ donations can also occur. An estimated 6-7 million people worldwide are infected with T. cruzi and up to 20-30% of them could develop cardiac disease if left untreated.