Benznidazole is an antiparasitic medication used in the treatment of Chagas disease. While it is highly effective in early disease this decreases in those who have long-term infection. It is the first-line treatment given its moderate side effects compared to nifurtimox. It is taken by mouth.Side effects are fairly common. They include rash, numbness, fever, muscle pain, loss of appetite, and trouble sleeping. Rare side effects include bone marrow suppression which can lead to low blood cell levels. It is not recommended during pregnancy or in people with severe liver or kidney disease. Benznidazole is in the nitroimidazole family of medication and works by the production of free radicals.Benznidazole came into medical use in 1971. It is on the World Health Organizations List of Essential Medicines. As of 2012, Laboratório Farmacêutico do Estado de Pernambuco, a government run pharmaceutical company in Brazil was the only producer. Medical uses
Benznidazole has a significant activity during the acute phase of Chagas disease, with a success rate of up to 80%. Its curative capabilities during the chronic phase are, however, limited.
Some studies have found parasitologic cure (a complete elimination of T. cruzi from the body) in children during the early stage of the chronic phase, but overall failure rate in chronically infected individuals is typically above 80%.Some studies indicate treatment with benznidazole during the chronic phase, even if incapable of producing parasitologic cure because it reduces electrocardiographic changes and delays worsening of the clinical condition of the patient.Benznidazole has proven to be effective in the treatment of reactivated  T. cruzi  infections caused by immunosuppression, such as in people with AIDS or in those under immunosuppressive therapy related to organ transplants. Children
Benznidazole can be used in children, with the same 5–7 mg/kg per day weight-based dosing regimen that is used to treat adult infections. A formulation for children up to two years of age is available. It was added to the WHO Essential Medicines List for Children in 2013. Children are found to be at a lower risk of adverse events compared to adults, possibly due to increased hepatic clearance of the drug. The most prevalent adverse effects in children were found to be gastrointestinal, dermatologic, and neurologic in nature. However, the incidence of severe dermatologic and neurologic adverse events is lower in the pediatric population compared to adults. It use for Chagas in children was approved by the FDA in the US in 2017. Pregnant women
Studies in animals have shown that benznidazole can cross the placenta. Due to its potential for teratogenicity, use of benznidazole in pregnancy is not recommended.