Usage
Furazolidone is a synthetic nitrofuran derivative with broad-spectrum antibacterial and antiprotozoal activity. It is primarily prescribed for the treatment of:
- Bacterial and protozoal diarrhea and enteritis caused by susceptible organisms, including Escherichia coli, Salmonella, Shigella, Proteus, Aerobacter aerogenes, Vibrio cholerae, and Giardia lamblia.
- Giardiasis
- Cholera
- Colitis
Pharmacological Classification: Antibiotic, Antiprotozoal
Mechanism of Action: Furazolidone interferes with several bacterial enzyme systems, primarily those involved in carbohydrate metabolism, ultimately leading to bacterial cell death. It inhibits the activity of various enzymes necessary for microbial growth and survival.
Alternate Names
While Furazolidone is the generic name, the brand name Furoxone is discontinued. Generic versions are available.
How It Works
Pharmacodynamics: Furazolidone exhibits bactericidal and antiprotozoal activity by interfering with multiple microbial enzyme systems, including those involved in carbohydrate metabolism. This action disrupts crucial metabolic pathways, ultimately causing microbial death. It is effective against various bacterial and protozoal pathogens within the gastrointestinal tract.
Pharmacokinetics:
- Absorption: Furazolidone is poorly absorbed from the gastrointestinal tract, which is advantageous for treating localized infections in the gut.
- Metabolism: It is rapidly and extensively metabolized, primarily through nitro-reduction to the aminofuran derivative.
- Elimination: The majority of the drug and its metabolites are excreted in the urine, with some elimination occurring via the feces.
Mode of Action: Furazolidone inhibits several microbial enzyme systems, disrupting their function at the cellular level. It interferes with bacterial and protozoal carbohydrate metabolism.
Receptor Binding, Enzyme Inhibition or Neurotransmitter Modulation: It acts as a weak monoamine oxidase inhibitor (MAOI).
Elimination Pathways: Primarily renal excretion, with some fecal elimination.
Dosage
Standard Dosage
Adults: 100 mg four times daily for 5-7 days. In some cases, treatment might extend up to 10 days for giardiasis.
Children:
- 1 month to 4 years: The dose is based on body weight (5mg/kg/day or 2.3mg/lb/day).
- 5 years and older: 25 to 50 mg four times daily.
Pediatric Safety Considerations: Furazolidone is not recommended for infants under one month of age due to the risk of hemolytic anemia.
Special Cases:
- Elderly Patients: Dosage adjustment may be necessary based on renal function.
- Patients with Renal Impairment: Dose reduction is necessary in patients with moderate to severe renal impairment.
- Patients with Hepatic Dysfunction: No specific dose adjustment is explicitly stated, but caution is advised.
- Patients with Comorbid Conditions: Use cautiously in patients with G6PD deficiency.
Clinical Use Cases
Furazolidone’s clinical use is generally confined to the treatment of bacterial and protozoal gastrointestinal infections as described above. It is not typically used in settings like intubation, surgical procedures, mechanical ventilation, ICU use, or emergency situations.
Dosage Adjustments
Dose adjustments are necessary in patients with renal impairment and for G6PD deficiency.
Side Effects
Common Side Effects
- Nausea
- Vomiting
- Headache
- Malaise
- Dizziness
- Brownish discoloration of urine
Rare but Serious Side Effects
- Hypersensitivity reactions (hypotension, urticaria, fever, arthralgia, rash)
- Hemolytic anemia (particularly in patients with G6PD deficiency)
- Pulmonary reactions
Long-Term Effects
No specific long-term side effects have been reported.
Adverse Drug Reactions (ADR)
Hypersensitivity reactions and hemolytic anemia are the most significant ADRs.
Contraindications
- Hypersensitivity to furazolidone or other nitrofurans.
- Infants under one month of age.
- Concomitant use of alcohol or within four days of furazolidone therapy.
- Concomitant use with MAOIs.
Drug Interactions
- Alcohol (disulfiram-like reaction).
- MAOIs (risk of hypertensive crisis).
- Tyramine-containing foods (risk of hypertensive crisis).
- Indirect-acting sympathomimetic amines.
- Certain antidepressants (e.g., tricyclics, SSRIs).
Pregnancy and Breastfeeding
Pregnancy Safety Category: C (Animal studies have shown adverse effects on the fetus, but there are no adequate and well-controlled studies in pregnant women. The drug should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.)
Breastfeeding: Furazolidone is not recommended during breastfeeding. It is unknown if it is excreted in breast milk, and the risk to infants under one month is significant due to the potential for hemolytic anemia.
Drug Profile Summary
- Mechanism of Action: Interferes with bacterial and protozoal enzyme systems.
- Side Effects: Nausea, vomiting, headache, malaise, hypersensitivity reactions, hemolytic anemia.
- Contraindications: Hypersensitivity, infants under one month, concomitant alcohol use, MAOIs.
- Drug Interactions: Alcohol, MAOIs, tyramine-containing foods, sympathomimetics, some antidepressants.
- Pregnancy & Breastfeeding: Not recommended.
- Dosage: Adults: 100 mg four times daily; Children: weight-based dosing (see above).
- Monitoring Parameters: Monitor for signs of hemolytic anemia, especially in patients with G6PD deficiency.
Popular Combinations
Furazolidone is sometimes used in combination with other antibiotics for H. pylori eradication, such as in a quadruple therapy containing a proton pump inhibitor, bismuth, and another antibiotic like tetracycline or metronidazole.
Precautions
- General Precautions: Screen patients for G6PD deficiency before administering. Avoid alcohol during and for four days after treatment.
- Pregnant Women: Not recommended.
- Breastfeeding Mothers: Not recommended.
- Children & Elderly: Not for use in infants under one month. Dosage adjustment may be needed in the elderly.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Furazolidone?
A: Adults: 100 mg four times daily. Children: weight-based dosing (see Dosage section). Infants under one month: Not recommended.
Q2: What are the common side effects?
A: Nausea, vomiting, headache, malaise, brown discoloration of urine.
Q3: What are the serious side effects?
A: Hemolytic anemia (especially in patients with G6PD deficiency), hypersensitivity reactions.
Q4: Can Furazolidone be used during pregnancy?
A: Not recommended. Category C drug.
Q5: Can Furazolidone be used during breastfeeding?
A: Not recommended.
Q6: What are the contraindications for Furazolidone?
A: Hypersensitivity to furazolidone, infants under one month of age, concurrent alcohol use, MAOIs.
Q7: What should patients avoid while taking Furazolidone?
A: Alcohol, tyramine-rich foods, MAOI drugs, certain other medications (as noted in Drug Interactions).
Q8: How does Furazolidone work?
A: It inhibits bacterial and protozoal enzyme systems, particularly those involved in carbohydrate metabolism.
Q9: What infections is Furazolidone used to treat?
A: Bacterial and protozoal diarrhea/enteritis, Giardiasis, Cholera, Colitis.
Q10: How long does Furazolidone treatment typically last?
A: 5-7 days, sometimes up to 10 days for Giardiasis.
