Causality and Severity of Adverse Reactions and Biochemical Changes to Benznidazole Treatment in Patients with Chronic Chagas Disease.

Background: Chagas disease (CD) is a serious public health problem in Latin America. Benznidazole (BNZ) is used for the treatment of CD and, despite its wide use, little information is available about its toxicity and mechanisms of adverse drug reactions (ADR).

Objectives: To identify and classify clinical and laboratory adverse reactions caused by BNZ in terms of causality and severity.

Methods: Prospective cohort study from January 2018 to December 2021. Treatment follow-up included visits and biochemical tests (complete blood count, liver and kidney function tests) before, during and after treatment. ADR were classified according to causality and severity. In the statistical analysis, the significance level was set at p<0.05.

Results: Forty patients with chronic CD were included. A high prevalence of ADR was observed 161 ADR in 30 patients [90%]; of these, 104 (64.6%) were classified as possible and 57 (35.4%) as probable. The ADR were classified as moderate and mild. Of the 40 patients, nine (22.5%) discontinued treatment. ADR associated with treatment discontinuation and interventions were those that affected the dermatological system, central and peripheral nervous system and sense organs such as ageusia. Mild hematological and biochemical changes such as lymphopenia were observed after 30 days of treatment.

Conclusion: Many patients were able to complete the treatment even with ADR, which can be attributed to the successful follow-up strategy with symptomatic treatment and counseling, leading to patient's awareness of symptoms and treatment adherence.