Dosing & Uses
Dosage Forms & Strengths
tablet
- 12.5mg
- 100mg (functionally scored)
Chagas Disease (Off-label)
CDC guidelines
- Treatment is strongly recommended for adults up to 50 years old with chronic infection who do not already have advanced Chagas cardiomyopathy
- For adults older than 50 years with chronic T cruzi infection, the decision to treat with antiparasitic drugs should be individualized, weighing the potential benefits and risks for the patient
- 5-7 mg/kg/day PO divided in 2 doses separated by ~12 hr x 60 days
- https://www.cdc.gov/parasites/chagas/health_professionals/tx.html
Dosage Forms & Strengths
tablet
- 12.5mg
- 100mg (functionally scored)
Chagas Disease
Indicated in children aged 2-12 years for treatment of Chagas disease (American trypanosomiasis) caused by Trypanosoma cruzi
<2 years: Safety and efficacy not established
2-12 years: 5-8 mg/kg/day PO divided in 2 doses separated by ~12 hr x 60 days
Also see Administration
Recommended weight-based doses
- <15 kg: 50 mg PO q12hr
- 15 kg to <20 kg: 62.5 mg PO q12hr
- 20 kg to <30 kg: 75 mg PO q12hr
- 30 kg to <40 kg: 100 mg PO q12hr
- 40 kg to <60 kg: 150 mg PO q12hr
- ≥60 kg: 100 mg PO q12hr
CDC guidelines
- Antiparasitic treatment is indicated for all cases of acute or reactivated Chagas disease and for chronic T cruzi infection in children up to age 18 years; congenital infections are considered acute disease
- <12 years: 5-7.5 mg/kg/day PO divided in 2 doses separated by ~12 hr x 60 days
- ≥12 years: 5-7 mg/kg/day PO divided in 2 doses separated by ~12 hr x 60 days
- https://www.cdc.gov/parasites/chagas/health_professionals/tx.html
Dosage Modifications
Not evaluated in patients with renal or hepatic impairment
Dosing Considerations
This indication is approved under accelerated approval based on the number of treated patients who became Immunoglobulin G (IgG) antibody negative against the recombinant antigens of T cruzi
Continued approval may be contingent upon verification and description of clinical benefit in confirmatory trials
Interactions
Interaction Checker
No Results

Contraindicated
Serious - Use Alternative
Significant - Monitor Closely
Minor

Contraindicated (2)
- disulfiram
benznidazole, disulfiram. Either increases toxicity of the other by aldehyde dehydrogenase inhibition. Contraindicated. Psychotic reactions have been reported in patients who were coadministered disulfiram and nitroimidazole agents (structurally related to benznidazole). Do not prescribe benznidazole to patients who have taken disulfiram within the last 2 weeks.
- ethanol
benznidazole increases toxicity of ethanol by aldehyde dehydrogenase inhibition. Contraindicated. Abdominal cramps, nausea, vomiting, headaches, and/or flushing may occur if alcoholic beverages or products containing propylene glycol are consumed during or following therapy with nitroimidazole agents (structurally related to benznidazole). Do not consume alcohol or products containing propylene glycol during and for at least 3 days after benznidazole therapy.
Serious - Use Alternative (6)
- axicabtagene ciloleucel
benznidazole, axicabtagene ciloleucel. Either increases effects of the other by immunosuppressive effects; risk of infection. Avoid or Use Alternate Drug.
- brexucabtagene autoleucel
benznidazole, brexucabtagene autoleucel. Either increases effects of the other by immunosuppressive effects; risk of infection. Avoid or Use Alternate Drug.
- ciltacabtagene autoleucel
benznidazole, ciltacabtagene autoleucel. Either increases effects of the other by immunosuppressive effects; risk of infection. Avoid or Use Alternate Drug.
- idecabtagene vicleucel
benznidazole, idecabtagene vicleucel. Either increases effects of the other by immunosuppressive effects; risk of infection. Avoid or Use Alternate Drug.
- lisocabtagene maraleucel
benznidazole, lisocabtagene maraleucel. Either increases effects of the other by immunosuppressive effects; risk of infection. Avoid or Use Alternate Drug.
- tisagenlecleucel
benznidazole, tisagenlecleucel. Either increases effects of the other by immunosuppressive effects; risk of infection. Avoid or Use Alternate Drug.
Monitor Closely (0)
Minor (0)
Adverse Effects
>10%
Abdominal pain (25%)
Rash or skin lesions (11-16%)
Weight decreased (13%)
1-10%
Nausea (5%)
Vomiting (5%)
Increased AST/ALT (5%)
Diarrhea (4%)
Dizziness (4%)
Peripheral neuropathy (2%)
Tremor (2%)
Postmarketing Reports
severe irreversible hepatotoxicity/acute liver failure (patients with Cockayne syndrome)
Warnings
Contraindications
Patients who have taken disulfiram within the last 2 weeks; psychotic reactions may occur
Patients with Cockayne syndrome
History of hypersensitivity reaction to benznidazole or other nitroimidazole derivatives; severe skin and soft tissue reactions reported
Cautions
Genotoxicity of benznidazole has been demonstrated in humans, in vitro in several bacterial species and mammalian cell systems, and in vivo in rodent
Carcinogenicity observed in mice and rats treated chronically with nitroimidazole agents which are structurally similar to benznidazole
Severe irreversible hepatotoxicity/acute liver failure with fatal outcomes reported after initiation of metronidazole, another nitroimidazole drug, structurally related to benznidazole in patients with Cockayne syndrome
Embryofetal toxicity may occur (see Pregnancy)
Skin disorders
- Serious skin and subcutaneous disorders reported, including acute generalized exanthematous pustulosis (AGEP), toxic epidermal necrolysis (TEN), erythema multiforme, and eosinophilic drug reaction
- Extensive skin reactions reported, such as rash (maculopapular, pruritic macules, eczema, pustules, erythematous, generalized, and allergic dermatitis, exfoliative dermatitis); most occurred after ~10 days of treatment; most rashes resolved with treatment discontinuation
- Discontinue drug for skin reactions presenting with additional symptoms or signs of systemic involvement (eg, lymphadenopathy, fever and/or purpura)
- Also see Contraindications
Central and peripheral nervous system effects
- Can cause paresthesia or symptoms of peripheral neuropathy that may take several months to resolve
- Headache and dizziness have been reported
- Immediately discontinue drug in cases where neurological symptoms occur; symptoms mostly occur late in the course of treatment
Hematological manifestations of bone marrow depression
- Hematological manifestations of bone marrow depression reported (eg, neutropenia, thrombocytopenia, anemia, leukopenia); typically resolves after discontinuing drug
- Patients with hematological manifestations of bone marrow depression must take benznidazole only under strict medical supervision
- Monitor complete blood count; total and differential leukocyte counts recommended before, during, and after therapy
Drug interaction overview
- Psychotic reactions reported with coadministration of disulfiram and nitroimidazole agents (structurally related to benznidazole); do not coadminister or use in patients who have taken disulfiram within the last 2 weeks (see Contraindications)
- Disulfiram-like reaction (abdominal cramps, nausea, vomiting, headaches, flushing) may occur if alcoholic beverages or products containing propylene glycol are consumed during or following therapy with nitroimidazole agents (structurally related to benznidazole); discontinue alcohol/propylene glycol use during and for at least 3 days following benznidazole therapy completion (see Contraindications)
Pregnancy
Pregnancy
Based on findings from animal studies, can cause fetal harm when administered to pregnant women
Obtain pregnancy test in females of reproductive potential before initiating treatment
Animal studies
- Benznidazole administered PO to pregnant rats and rabbits during organogenesis was associated with fetal malformations at doses ~1-3 times the maximum recommended human dose (MRHD) in rats (anasarca, anophthalmia, and/or microphthalmia) and doses ~0.3-1 times the MRHD in rabbits (ventricular septal defect)
Contraception
- Advise females of reproductive potential to use effective contraception during treatment and for 5 days after the final dose
Fertility
- Based on findings in rodents, may impair fertility in males of reproductive potential
- Unknown whether effects on fertility are reversible
Lactation
Present in human milk at infant doses of 5.5-17% of the maternal weight-adjusted dosage and a milk/plasma ratio ranging between 0.32.79
Because of the potential for serious adverse reactions and transmission of Chagas disease, advise patients that breastfeeding is not recommended during treatment
Pregnancy Categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk. C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done. D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk. X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist. NA: Information not available.Pharmacology
Mechanism of Action
Nitroimidazole antimicrobial; generates radical species in both aerobic and anaerobic conditions that are capable of damaging parasitic DNA
Inhibits DNA, RNA, and protein synthesis within the T cruzi parasite
Studies suggest benznidazole is reduced by a Type I nitroreductase (NTR) enzyme of T cruzi producing a series of short-lived intermediates that may promote damage to several macromolecules including DNA
Absorption
Peak plasma concentration: 2.4 mg/L
Peak plasma time: 2 hr (fasting); 3.2 hr (high-fat, high-caloric meal)
AUC: 41.8-44.1 mg·h/L
Distribution
Protein bound: 44-60%
Metabolism
Unknown pathway
Elimination
Half-life: 13 hr (single-dose in healthy volunteers)
Excretion: Urine and feces
Administration
Oral Preparation
Dosage based on body weight; 100-mg tablets are scored and can be split in half (50 mg) or quarters (25 mg) to enable precise dosing
Slurry preparation
- 12.5-mg and 100-mg tablets can be made into slurry as an alternative method of administration
- Place prescribed dose of 12.5-mg or 100-mg tablets into a cup and add specific volume of water per number of tablets
- Allow tablets to disintegrate in cup over ~1-2 minutes
- Shake contents of cup gently to mix
- Drink the contents of the cup (slurry of tablets with water) immediately
- Rinse the cup with an additional water, 10 mL (weight <30 kg) or 80 mL (weight ≥30 kg), and drink the whole amount; repeat rinse with 80 mL (weight ≥30 kg) and drink again
Weight <30 kg (prepare slurry with 12.5-mg tab)
- <15 kg: 50 mg (4 tab)/dose in 40 mL water
- 15 to <20 kg: 62.5 mg (5 tab)/dose in 50 mL water
- 20 kg to <30 kg: 75 mg (6 tab)/dose in 60 mL water
Weight ≥30 kg (prepare slurry with 100-mg tab)
- 30 to <40 kg: 100 mg (1 tab)/dose in 80 mL water
- 40 to <60 kg: 150 mg (1.5 tab)/dose in 120 mL water
- ≥60 kg: 200 mg (2 tab)/dose in 160 mL water
Oral Administration
May take with or without food
Storage
Store at controlled room temperature 20-25°C (68-77°F); excursions permitted to 15-30°C (59-86°F)
Keep bottle tightly closed and protect from moisture
Images
BRAND | FORM. | UNIT PRICE | PILL IMAGE |
---|---|---|---|
benznidazole oral - | 100 mg tablet | ![]() | |
benznidazole oral - | 12.5 mg tablet | ![]() |
Copyright © 2010 First DataBank, Inc.
Formulary
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