benznidazole

General

Pronunciation:
benz-nid-a-zole

Ther. Class.
antiprotozoals

Pharm. Class.
imidazoles

Indications

Chagas disease.

Action

Disrupts DNA, RNA, and protein synthesis in susceptible organisms.

Therapeutic Effect(s):

Resolution of infection.

Spectrum:

Active against Trypanosoma cruzi.

Pharmacokinetics

Absorption: Rapidly and completely absorbed following oral administration.

Distribution: Unknown.

Metabolism and Excretion: Metabolic pathway unknown; excreted in urine and feces.

Half-life: 13 hr.

TIME/ACTION PROFILE (plasma levels)

ROUTEONSETPEAKDURATION
POunknown2 hr12 hr

Contraindication/Precautions

Contraindicated in:

  • Hypersensitivity to benznidazole or other nitroimidazole derivatives (cross-sensitivity may occur);
  • Current or previous use (in past 2 wk) of disulfiram;
  • Concurrent use of products containing alcohol or propylene glycol;
  • OB: May cause fetal harm; avoid use during pregnancy;
  • Lactation: Avoid breast feeding.

Use Cautiously in:

  • Rep: Women of reproductive potential;
  • Pedi: Children <2 yr and >12 yr (safety and effectiveness not established).

Adverse Reactions/Side Effects

CNS: dizziness, headache

Derm: ACUTE GENERALIZED EXANTHEMATOUS PUSTULOSIS, EOSINOPHILIC DRUG REACTION, ERYTHEMA MULTIFORME, TOXIC EPIDERMAL NECROLYSIS, rash, urticaria

GI: abdominal pain, ↓ appetite, diarrhea, ↑ liver enzymes, nausea, vomiting

GU: ↓ fertility (males)

Hemat: anemia, eosinophilia, leukopenia, neutropenia, thrombocytopenia

Metabolic: ↓ weight

MS: arthralgia

Neuro: peripheral neuropathy, tremor

* CAPITALS indicate life-threatening.
Underline indicate most frequent.

Interactions

Drug-Drug

  • Concurrent use with disulfiram may result in psychotic reactions; concurent use and use of disulfiram in past 2 wk contraindicated.
  • Disulfiram-like reaction may occur with ingestion of products containing alcohol or propylene glycol; use during and ≥3 days after therapy contraindicated.

Route/Dosage

PO (Children 2–12 yr and ≥60 kg) 200 mg every 12 hr for 60 days.

PO (Children 2–12 yr and 40–59 kg) 150 mg every 12 hr for 60 days.

PO (Children 2–12 yr and 30–39 kg) 100 mg every 12 hr for 60 days.

PO (Children 2–12 yr and 20–29 kg) 75 mg every 12 hr for 60 days.

PO (Children 2–12 yr and 15–19 kg) 62.5 mg every 12 hr for 60 days.

PO (Children 2–12 yr and <15 kg) 50 mg every 12 hr for 60 days.

Availability

Tablets: 12.5 mg, 100 mg

Assessment

  • Assess for signs and symptoms of skin reactions (rash with maculopapular, pruritic macules; eczema; pustules; erythematous, generalized, and allergic dermatitis, exfoliative dermatitis) periodically during therapy. Usually occurs after 10 days of therapy and resolves with discontinuation.
  • Assess for signs and symptoms of peripheral neuropathy (paresthesia, burning, tingling, numbness) in hands or feet periodically during therapy. If symptoms occur discontinue immediately.

Lab Test Considerations: Obtain pregnancy test before starting therapy.

  • May cause anemia and leukopenia.

Potential Diagnoses

Implementation

  • PO Administer twice daily, approximately 12 hrs apart, without regard to food. Tablets may be split in half or quarters for doses <100 mg.
    • Weight <30 kg: May be made into slurry by placing prescribed number of 12.5 mg tablets into cup and adding water. For patients <15 kg, 50 mg dose, place 4 tablets in 40 mL water. For patients 15 kg to <20 kg, 62.5 mg dose, place 5 tablets in 50 mL water. For patients 20 kg to <30 kg, 75 mg dose, 6 tablets, place 6 tablets in 60 mL water. Allow tablets to disintegrate over 1–2 min, shake gently to mix. Drink slurry immediately, then rinse cup with 10 mL water and drink whole amount. Weight ≥30 kg: May be made into slurry by placing prescribed number of 100 mg tablets into cup and adding water. For patients 30 kg to <40 kg, 100 mg dose, place 1 tablet in 80 mL water. For patients 40 kg to <60 kg, 150 mg dose, place 1.5 tablet in 120 mL water. For patients ≥60 kg, 200 mg dose, place 2 tablets in 160 mL water. Allow tablets to disintegrate over 1–2 min, shake gently to mix. Drink slurry immediately, then rinse cup with 80 mL water and drink whole amount. Repeat rinse with 80 mL of water and drink again.

Patient/Family Teaching

  • Instruct patient and parents to take benznidazole as directed for 60 days.
  • Caution patient to avoid intake of alcoholic beverages or preparations containing alcohol during and for at least 3 days after treatment with benznidazole. May cause a disulfiram-like reaction (flushing, nausea, vomiting, headache, abdominal cramps).
  • Rep: May be teratogenic. Advise female patient to use effective contraception during and for at least 5 days after last dose and to avoid breast feeding during therapy. Inform male patients that benznidazole may impair fertility.

Evaluation/Desired Outcomes

Resolution of signs and symptoms of Chagas disease.

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