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Benznidazole

Medically reviewed on August 12, 2018

Pronunciation

(benz NID a zole)

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Tablet, Oral:

Generic: 12.5 mg, 100 mg

Pharmacologic Category

  • Antiprotozoal, Nitroimidazole
  • Antitrypanosomal

Pharmacology

Inhibits the synthesis of DNA, RNA, and proteins within the T. cruzi parasite.

Absorption

Rapid (Bern 2007)

Metabolism

Unknown

Excretion

Urine and feces

Time to Peak

Median: 2 hours

Half-Life Elimination

~13 hours

Protein Binding

~44% to 60%

Use: Labeled Indications

Chagas disease: Treatment of Chagas disease (American trypanosomiasis) caused by Trypanosoma cruzi in pediatric patients 2 to 12 years of age.

Contraindications

Hypersensitivity to benznidazole, other nitroimidazole derivatives, or any component of the formulation; disulfiram within previous 2 weeks of benznidazole therapy; consumption of alcoholic beverages or products containing propylene glycol during and for at least 3 days after therapy with benznidazole

Dosing: Adult

Chagas disease (off-label use): Oral: 5 to 7 mg/kg/day in 2 divided doses for 60 days (Bern 2007; CDC 2017)

Dosing: Geriatric

Refer to adult dosing.

Dosing: Pediatric

Chagas disease:

Children 2 to 12 years of age: Oral: 5 to 8 mg/kg/day in 2 divided doses for 60 days

Adolescents (off-label use): Oral: Refer to adult dosing.

Dosing: Renal Impairment

There are no dosage adjustments provided in the manufacturer's labeling (has not been studied).

Dosing: Hepatic Impairment

There are no dosage adjustments provided in the manufacturer's labeling (has not been studied).

Administration

Administer with or without food, approximately 12 hours apart.

To make slurry using 12.5 or 100 mg tablets:

Place prescribed dose in a cup and add the specified volume of water (also refer to manufacturer's labeling):

12.5 mg tablets: 40 mL for 4 tablets, 50 mL for 5 tablets, or 60 mL for 6 tablets

100 mg tablets: 80 mL for 1 tablet, 120 mL for 1.5 tablets, or 160 mL for 2 tablets

Allow tablets to disintegrate over 1 to 2 minutes. Shake cup gently to mix and administer contents immediately. For 12.5 mg tablets, rinse cup with an additional 10 mL of water and administer entire amount. For 100 mg tablets, rinse cup with an additional 80 mL of water and administer entire amount; repeat this rinse with 80 mL and drink again.

Storage

Store at 20°C to 25°C (68°F to 77°F); excursions permitted to 15°C to 30°C (59°F to 86°F). Protect from moisture.

Drug Interactions

Alcohol (Ethyl): Benznidazole may enhance the adverse/toxic effect of Alcohol (Ethyl). A disulfiram-like reaction may occur. Avoid combination

Disulfiram: Benznidazole may enhance the adverse/toxic effect of Disulfiram. In particular, the risk for CNS toxicities such as psychosis may be increased. Avoid combination

Products Containing Propylene Glycol: Benznidazole may enhance the adverse/toxic effect of Products Containing Propylene Glycol. Avoid combination

Adverse Reactions

>10%:

Dermatologic: Skin rash (16%), skin lesion (11%)

Endocrine & metabolic: Weight loss (13%)

Gastrointestinal: Abdominal pain (25%), decreased appetite (5%)

1% to 10%:

Central nervous system: Headache (7%), peripheral neuropathy (2%)

Gastrointestinal: Nausea (5%), vomiting (5%), anorexia (<5%), diarrhea (4%)

Hepatic: Increased serum transaminases (5%)

Neuromuscular & skeletal: Arthralgia (<5%), tremor (2%)

<1%, postmarketing, and/or case reports: Acute generalized exanthematous pustulosis, ageusia, agranulocytosis, amnesia, arthritis, disorientation, dress syndrome, edema, epigastric pain, erythema multiforme, erythematous plaques, erythematous rash, exfoliation of skin, exfoliative dermatitis, eyelid edema, fatigue, fever, granulocytopenia, headache, hepatitis, hypoesthesia, increased serum alkaline phosphatase, increased serum bilirubin, insomnia, lack of concentration, lymphadenopathy, maculopapular rash, musculoskeletal pain, myalgia, paresthesia, pruritic rash, seizure, skin blister, swelling of extremities, thrombocytopenia, toxic epidermal necrolysis, toxic hepatitis, weakness, xerostomia

Warnings/Precautions

Concerns related to adverse effects:

• Carcinogenic/genotoxic: Carcinogenicity has been observed in mice and rats with nitroimidazole agents that are structurally similar to benznidazole in animal studies; it is unknown whether benznidazole is associated with carcinogenicity in humans. Genotoxicity (two-fold increase in chromosomal aberrations) of benznidazole has been demonstrated in one study of pediatric patients (11 months to 11 years) with Chagas disease.

• CNS effects: Paresthesia and/or peripheral neuropathy have been reported and may take several months to resolve; in general, these symptoms occur late in the course of treatment. Headache and dizziness have also been reported. Discontinue treatment if neurologic signs or symptoms occur.

• Dermatologic reactions: Serious skin and subcutaneous disorders (eg, acute generalized exanthematous pustulosis, toxic epidermal necrolysis, erythema multiforme, eosinophilic drug reaction) have been reported. Extensive skin reactions (eg, rash [maculopapular, pruritic macules, eczema, pustules, erythematous, generalized], allergic dermatitis, exfoliative dermatitis) have also been reported, most cases occurring after ~10 days of treatment; most rashes resolved with treatment discontinuation. Discontinue treatment at first evidence of a serious cutaneous reaction or skin reactions presenting with systemic signs/symptoms (eg, lymphadenopathy, fever, purpura).

• Hematologic effects: Bone marrow depression (eg, neutropenia, thrombocytopenia, anemia, leukopenia) that resolved after treatment discontinuation has been reported. Use benznidazole with caution and under strict medical supervision in patients with hematological manifestations of bone marrow depression. Monitor CBC, as well as total and differential leukocyte counts, prior to initiation, during treatment, and after discontinuation of treatment.

Concurrent drug therapy issues:

• Drug-drug interactions: Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information.

Other warnings/precautions:

• Ethanol use: Abdominal cramps, nausea, vomiting, headaches, and flushing have been reported with nitroimidazole agents that are structurally related to benznidazole and concomitant alcohol consumption (disulfiram-like reactions); avoid alcoholic beverages or products containing propylene glycol during and for at least 3 days after therapy.

Monitoring Parameters

CBC and total and differential leukocyte counts prior to initiation, during treatment, and after discontinuation; pregnancy test prior to initiation in female patients; signs of skin rash or neurologic signs/symptoms during treatment.

Pregnancy Considerations

Adverse events were observed in animal reproduction studies. Information related to the use of benznidazole for the treatment of acute Chagas disease in pregnant women is limited; treatment of chronic disease during pregnancy is not recommended.

Congenital transmission of Chagas disease may occur and the actual risk may depend on stage of maternal disease and geographic location (Bittencourt 1992). There are no specific recommendations for preventing vertical transmission of disease in women who are already pregnant. Because treatment is associated with a high risk of adverse events in adults and there is lack of data on possible teratogenic effects, treatment during pregnancy is not currently recommended (Carlier 2011). However, therapy with benznidazole prior to pregnancy in women who test positive for Trypanosoma cruzi antibodies may be used to prevent congenital transmission (Alvarez 2017; Carlier 2011).

Females of reproductive potential should have a pregnancy test prior to therapy. Effective contraception should be used during treatment and for 5 days after the last dose.

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Patient may experience abdominal pain, weight loss, nausea, vomiting, or lack of appetite. Have caregiver report immediately to prescriber burning or numbness feeling, headache, dizziness, swollen glands, signs of toxic epidermal necrolysis (red, swollen, blistered, or peeling skin [with or without fever]; red or irritated eyes; or sores in mouth, throat, nose, or eyes), signs of infection, bruising, bleeding, or severe loss of strength and energy (HCAHPS).

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for health care professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience, and judgment in diagnosing, treating, and advising patients.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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