Benznidazole 100mg Tablets
It is used to treat Chagas disease.
Drug Class
Antiparasitic
Pharmacologic Class
Nitroimidazole derivative
Pregnancy Category
Not available
FDA Approved
Aug 2017
DEA Schedule
Not Controlled
Overview
What is this medicine?
Benznidazole is a medicine used to treat Chagas disease, an infection caused by a parasite. It works by killing the parasite. It's important to take this medicine exactly as prescribed by your doctor for the full duration, even if you start feeling better, to ensure the infection is fully cleared.
How to Use This Medicine
Taking Your Medication
To take this medication correctly, you can take it with or without food. If necessary, you can mix it with water to create a slurry, but be sure to follow the instructions provided by your doctor. If you have 100 mg tablets, they can be split to achieve the required dose, but only split them along the score line.
Storing and Disposing of Your Medication
To store your medication properly, keep it at room temperature in a dry place, avoiding the bathroom. Ensure the lid is tightly closed, and store all medications in a safe location, out of the reach of children and pets.
What to Do If You Miss a Dose
If you miss a dose, give it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not give two doses at the same time or take extra doses.
To take this medication correctly, you can take it with or without food. If necessary, you can mix it with water to create a slurry, but be sure to follow the instructions provided by your doctor. If you have 100 mg tablets, they can be split to achieve the required dose, but only split them along the score line.
Storing and Disposing of Your Medication
To store your medication properly, keep it at room temperature in a dry place, avoiding the bathroom. Ensure the lid is tightly closed, and store all medications in a safe location, out of the reach of children and pets.
What to Do If You Miss a Dose
If you miss a dose, give it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not give two doses at the same time or take extra doses.
Lifestyle & Tips
- Avoid alcohol during treatment and for at least 3 days after stopping Benznidazole, as it can cause severe nausea, vomiting, stomach cramps, and headache.
- Report any new or worsening symptoms to your doctor immediately, especially skin rashes, numbness or tingling in your hands or feet, unusual tiredness, fever, or yellowing of your skin or eyes.
Available Forms & Alternatives
Available Strengths:
Dosing & Administration
Adult Dosing
Standard Dose:
300 mg daily (150 mg twice daily) for 60 days
Condition-Specific Dosing:
Chagas disease:
300 mg daily (150 mg twice daily) for 60 days
Pediatric Dosing
Neonatal:
Not established (safety and efficacy not established in children less than 2 years of age)
Infant:
5 to 8 mg/kg/day orally in 2 divided doses for 60 days (for children 2 to 12 years of age)
Child:
5 to 8 mg/kg/day orally in 2 divided doses for 60 days (for children 2 to 12 years of age)
Adolescent:
5 to 8 mg/kg/day orally in 2 divided doses for 60 days (for children 12 to 18 years of age, up to a maximum of 300 mg/day)
Dose Adjustments
Renal Impairment:
Mild:
No specific dose adjustment recommended, but monitor for adverse reactions.
Moderate:
No specific dose adjustment recommended, but monitor for adverse reactions.
Severe:
No specific dose adjustment recommended, but monitor for adverse reactions. Use with caution.
Dialysis:
Not available. Benznidazole is not significantly removed by hemodialysis.
Hepatic Impairment:
Mild:
No specific dose adjustment recommended, but monitor for adverse reactions.
Moderate:
No specific dose adjustment recommended, but monitor for adverse reactions. Use with caution.
Severe:
No specific dose adjustment recommended, but monitor for adverse reactions. Use with caution.
Pharmacology
Mechanism of Action
Benznidazole is a nitroimidazole derivative. Its mechanism of action against *Trypanosoma cruzi* involves the reduction of its nitro group by parasite nitroreductases, leading to the formation of reactive metabolites. These metabolites cause oxidative stress, damage to macromolecules (DNA, RNA, proteins, lipids), and ultimately lead to parasite death. It is thought to interfere with DNA synthesis and other vital cellular processes in the parasite.
Pharmacokinetics
Absorption:
Bioavailability:
High (approximately 90%)
Tmax:
2-4 hours
FoodEffect:
Food does not significantly affect absorption.
Distribution:
Vd:
Approximately 0.7 L/kg
ProteinBinding:
Approximately 90-97%
CnssPenetration:
Yes (crosses the blood-brain barrier, achieving therapeutic concentrations in CSF)
Elimination:
HalfLife:
Approximately 10-13 hours (terminal half-life)
Clearance:
Approximately 0.05 L/hr/kg
ExcretionRoute:
Primarily renal (approximately 60% as metabolites, less than 1% as unchanged drug) and fecal (approximately 25% as metabolites).
Unchanged:
Less than 1%
Pharmacodynamics
OnsetOfAction:
Not directly applicable for antiparasitic effect, as it requires sustained exposure.
PeakEffect:
Not directly applicable for antiparasitic effect.
DurationOfAction:
Antiparasitic effect persists as long as therapeutic concentrations are maintained during the 60-day treatment course.
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If your child exhibits any of the following symptoms, contact their doctor or seek immediate medical attention:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin (with or without fever)
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Dizziness or headache
Severe skin reactions, including:
+ Toxic epidermal necrolysis (TEN)
+ Red, swollen, blistered, or peeling skin
+ Red or irritated eyes
+ Sores in the mouth, throat, nose, eyes, genitals, or any areas of skin
+ Fever
+ Chills
+ Body aches
+ Shortness of breath
+ Swollen glands
Nerve problems, such as:
+ Burning
+ Numbness
+ Tingling (these symptoms may take several months to resolve after stopping the medication)
Low blood cell counts, which can increase the risk of:
+ Infections
+ Bleeding problems
+ Anemia
+ Signs of infection, such as fever, chills, or sore throat
+ Unexplained bruising or bleeding
+ Feeling very tired or weak
Other Possible Side Effects
Like all medications, this drug can cause side effects. Many people experience no side effects or only mild ones. If your child experiences any of the following side effects, or if they bother your child or do not go away, contact their doctor:
Stomach pain
Weight loss
Upset stomach or vomiting
* Decreased appetite
This is not an exhaustive list of possible side effects. If you have questions or concerns about side effects, contact your child's doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If your child exhibits any of the following symptoms, contact their doctor or seek immediate medical attention:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin (with or without fever)
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Dizziness or headache
Severe skin reactions, including:
+ Toxic epidermal necrolysis (TEN)
+ Red, swollen, blistered, or peeling skin
+ Red or irritated eyes
+ Sores in the mouth, throat, nose, eyes, genitals, or any areas of skin
+ Fever
+ Chills
+ Body aches
+ Shortness of breath
+ Swollen glands
Nerve problems, such as:
+ Burning
+ Numbness
+ Tingling (these symptoms may take several months to resolve after stopping the medication)
Low blood cell counts, which can increase the risk of:
+ Infections
+ Bleeding problems
+ Anemia
+ Signs of infection, such as fever, chills, or sore throat
+ Unexplained bruising or bleeding
+ Feeling very tired or weak
Other Possible Side Effects
Like all medications, this drug can cause side effects. Many people experience no side effects or only mild ones. If your child experiences any of the following side effects, or if they bother your child or do not go away, contact their doctor:
Stomach pain
Weight loss
Upset stomach or vomiting
* Decreased appetite
This is not an exhaustive list of possible side effects. If you have questions or concerns about side effects, contact your child's doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Severe skin rash, blistering, or peeling skin
- Swelling of the face, lips, tongue, or throat
- Difficulty breathing or swallowing
- Numbness, tingling, burning, or weakness in hands or feet (signs of peripheral neuropathy)
- Unusual bleeding or bruising
- Persistent sore throat, fever, or signs of infection
- Yellowing of the skin or eyes (jaundice)
- Dark urine or pale stools
- Severe stomach pain, nausea, or vomiting
Before Using This Medicine
Before Your Child Takes This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
If your child is allergic to this medication, any of its components, or any other medications, foods, or substances. Please describe the allergy and the symptoms your child experienced.
If your child has Cockayne syndrome, as some individuals with this condition have developed liver problems while taking this medication. In some cases, these liver problems have been persistent or even fatal.
If your child has taken disulfiram within the past 14 days.
If your child is breastfeeding, as they should not breastfeed while taking this medication.
This is not an exhaustive list of all potential interactions with this medication. Therefore, it is crucial to discuss all of your child's medications (prescription, over-the-counter, natural products, and vitamins) and health conditions with their doctor and pharmacist. This will help ensure that it is safe to administer this medication in conjunction with other medications and health conditions. Never start, stop, or modify the dosage of any medication your child is taking without first consulting their doctor.
It is essential to inform your doctor about the following:
If your child is allergic to this medication, any of its components, or any other medications, foods, or substances. Please describe the allergy and the symptoms your child experienced.
If your child has Cockayne syndrome, as some individuals with this condition have developed liver problems while taking this medication. In some cases, these liver problems have been persistent or even fatal.
If your child has taken disulfiram within the past 14 days.
If your child is breastfeeding, as they should not breastfeed while taking this medication.
This is not an exhaustive list of all potential interactions with this medication. Therefore, it is crucial to discuss all of your child's medications (prescription, over-the-counter, natural products, and vitamins) and health conditions with their doctor and pharmacist. This will help ensure that it is safe to administer this medication in conjunction with other medications and health conditions. Never start, stop, or modify the dosage of any medication your child is taking without first consulting their doctor.
Precautions & Cautions
It is essential to inform all of your child's healthcare providers, including doctors, nurses, pharmacists, and dentists, that your child is taking this medication. If your child experiences any changes in weight, consult with their doctor, as their dosage may need to be adjusted.
Regular blood work and laboratory tests, as directed by the doctor, are crucial to monitor your child's health while taking this medication. Research has shown that a similar drug has been associated with an increased risk of cancer in mice and rats, although it is unclear if this medication poses the same risk to humans. If you have concerns, discuss them with your child's doctor.
For children of childbearing age, a pregnancy test is required before initiating this medication to confirm they are not pregnant. Additionally, studies in male rats have shown that this medication can cause fertility problems, which may resolve after discontinuing the drug. However, it is unknown if this medication will have a similar effect on human fertility.
If your child is sexually active or may become sexually active, it is crucial to be aware of the potential risks. This medication may harm an unborn baby if taken during pregnancy. To prevent this, your child should use effective birth control while taking this medication and for a specified period after the last dose. Consult with the doctor to determine the recommended duration of birth control use. If your child becomes pregnant while taking this medication, contact their doctor immediately.
Regular blood work and laboratory tests, as directed by the doctor, are crucial to monitor your child's health while taking this medication. Research has shown that a similar drug has been associated with an increased risk of cancer in mice and rats, although it is unclear if this medication poses the same risk to humans. If you have concerns, discuss them with your child's doctor.
For children of childbearing age, a pregnancy test is required before initiating this medication to confirm they are not pregnant. Additionally, studies in male rats have shown that this medication can cause fertility problems, which may resolve after discontinuing the drug. However, it is unknown if this medication will have a similar effect on human fertility.
If your child is sexually active or may become sexually active, it is crucial to be aware of the potential risks. This medication may harm an unborn baby if taken during pregnancy. To prevent this, your child should use effective birth control while taking this medication and for a specified period after the last dose. Consult with the doctor to determine the recommended duration of birth control use. If your child becomes pregnant while taking this medication, contact their doctor immediately.
Overdose Information
Overdose Symptoms:
- Exaggerated adverse effects, particularly peripheral neuropathy (e.g., severe paresthesias, motor weakness)
- Bone marrow depression
- Hepatotoxicity
What to Do:
There is no specific antidote for benznidazole overdose. Treatment should be symptomatic and supportive. Benznidazole is not significantly removed by hemodialysis. Contact a poison control center immediately (Call 1-800-222-1222 in the US).
Drug Interactions
Monitoring
Baseline Monitoring
Complete Blood Count (CBC) with differential
Rationale: To establish baseline and monitor for bone marrow suppression (leukopenia, neutropenia, agranulocytosis), a known adverse effect.
Timing: Prior to initiation of treatment
Liver Function Tests (LFTs) including AST, ALT, bilirubin
Rationale: To establish baseline and monitor for hepatotoxicity.
Timing: Prior to initiation of treatment
Neurological examination
Rationale: To establish baseline and monitor for peripheral neuropathy.
Timing: Prior to initiation of treatment
Routine Monitoring
Complete Blood Count (CBC) with differential
Frequency: Every 2-4 weeks during treatment, or more frequently if clinically indicated.
Target: Within normal limits; significant drops warrant dose interruption or discontinuation.
Action Threshold: Significant leukopenia, neutropenia, or agranulocytosis; consider dose interruption or discontinuation.
Liver Function Tests (LFTs)
Frequency: Every 2-4 weeks during treatment, or more frequently if clinically indicated.
Target: Within normal limits; significant elevations warrant dose interruption or discontinuation.
Action Threshold: Significant elevation of transaminases (e.g., >3x ULN with symptoms, or >5x ULN without symptoms); consider dose interruption or discontinuation.
Neurological assessment (e.g., sensory and motor function)
Frequency: Regularly during treatment, especially if patient reports symptoms.
Target: No new or worsening neurological symptoms.
Action Threshold: Development or worsening of peripheral neuropathy (e.g., paresthesias, numbness, weakness); consider dose reduction or discontinuation.
Skin examination
Frequency: Regularly during treatment.
Target: No new or worsening rash.
Action Threshold: Development of severe rash, exfoliative dermatitis, or signs of hypersensitivity (e.g., DRESS syndrome); discontinue immediately.
Symptom Monitoring
- Skin rash (erythematous, maculopapular, urticarial)
- Peripheral neuropathy (numbness, tingling, pain, weakness in extremities)
- Gastrointestinal symptoms (abdominal pain, nausea, vomiting, anorexia)
- Fatigue, malaise
- Fever
- Swollen lymph nodes
- Joint pain
- Signs of liver injury (jaundice, dark urine, persistent nausea/vomiting)
- Signs of bone marrow suppression (unusual bleeding/bruising, persistent infections, fever)
Special Patient Groups
Pregnancy
Benznidazole should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. There are no adequate and well-controlled studies in pregnant women. Animal studies have shown adverse effects on fetal development.
Trimester-Specific Risks:
First Trimester:
Potential for teratogenicity based on animal data; use only if clearly needed.
Second Trimester:
Potential for adverse effects; use with caution.
Third Trimester:
Potential for adverse effects; use with caution.
Lactation
It is not known whether benznidazole is excreted in human milk. Due to the potential for serious adverse reactions in breastfed infants, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
Infant Risk:
Not available; potential for serious adverse effects.
Pediatric Use
Approved for use in pediatric patients 2 years of age and older. Safety and efficacy have not been established in children younger than 2 years of age. Dosing is weight-based.
Geriatric Use
Clinical studies of benznidazole did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.
Clinical Information
Clinical Pearls
- Benznidazole is the only FDA-approved treatment for Chagas disease in the US.
- Treatment duration is typically 60 days and adherence is crucial for efficacy.
- Patients should be closely monitored for adverse effects, especially skin reactions, peripheral neuropathy, and bone marrow suppression, throughout the entire treatment period and for a period after discontinuation.
- Hypersensitivity reactions can be severe and may require immediate discontinuation.
- Peripheral neuropathy is a common and potentially dose-limiting adverse effect; monitor for symptoms and consider dose reduction or discontinuation if it develops.
- Advise patients to avoid alcohol due to the potential for a disulfiram-like reaction.
- Benznidazole tablets can be crushed and mixed with water for easier administration in pediatric patients or those with swallowing difficulties.
Alternative Therapies
- Nifurtimox (another nitrofurane derivative, also approved for Chagas disease)
Cost & Coverage
Average Cost:
Not readily available (orphan drug, specific pricing) per 30 tablets
Insurance Coverage:
Specialty Tier (often requires prior authorization due to orphan drug status and specific indication)
General Drug Facts
If your child's symptoms or health issues persist or worsen, it is essential to contact their doctor promptly. To ensure safe and effective treatment, never share your child's medication with others, and do not administer someone else's medication to your child. For detailed information about this medication, consult the patient information leaflet that may accompany it. If you have any questions or concerns, discuss them with your child's doctor, nurse, pharmacist, or other healthcare provider. Additionally, you can check with your pharmacist to see if there is a separate patient information leaflet available for this drug. In the event of a suspected overdose, immediately call the poison control center or seek medical attention. Be prepared to provide critical information, including the name of the medication taken, the quantity, and the time it was taken, to facilitate prompt and appropriate care.