Nitrofurantoin

Pronunciation

(nye troe fyoor AN toyn)

U.S. Brand Names

Furadantin®; Macrobid®; Macrodantin®

Generic Available

Yes: Excludes suspension

Canadian Brand Names

Apo-Nitrofurantoin®; Macrobid®; Macrodantin®; Novo-Furantoin

Use

Prevention and treatment of urinary tract infections caused by susceptible gram-negative and some gram-positive organisms; Pseudomonas , Serratia , and most species of Proteus are generally resistant to nitrofurantoin

Pregnancy Risk Factor

B (contraindicated at term)

Pregnancy Implications

Teratogenic effects have not been observed, however, may cause hemolytic anemia in infants. Use of nitrofurantoin is contraindicated at term (38-42 weeks gestation), during labor and delivery, or when the onset of labor is imminent.

Lactation

Enters breast milk/not recommended (infants <1 month); AAP rates "compatible"

Contraindications

Hypersensitivity to nitrofurantoin or any component of the formulation; renal impairment (anuria, oliguria, significantly elevated serum creatinine, or Clcr< 60 mL/minute); infants <1 month (due to the possibility of hemolytic anemia); pregnancy at term (38-42 weeks gestation), during labor and delivery, or when the onset of labor is imminent

Warnings/Precautions

Use with caution in patients with G6PD deficiency or in patients with anemia. Therapeutic concentrations of nitrofurantoin are not attained in urine of patients with Clcr<60 mL/minute. Use with caution if prolonged therapy is anticipated due to possible pulmonary toxicity. Acute, subacute, or chronic (usually after 6 months of therapy) pulmonary reactions have been observed in patients treated with nitrofurantoin; if these occur, discontinue therapy immediately; monitor closely for malaise, dyspnea, cough, fever, radiologic evidence of diffuse interstitial pneumonitis or fibrosis. Rare, but severe hepatic reactions have been associated with nitrofurantoin (onset may be insidious); discontinue immediately if hepatitis occurs. Has been associated with peripheral neuropathy (rare); risk may be increased by renal impairment, diabetes, vitamin B deficiency, or electrolyte imbalance; use caution.

Adverse Reactions

Frequency not defined.

Cardiovascular: Chest pain, cyanosis, ECG changes (associated with pulmonary toxicity)

Central nervous system: Chills, depression, dizziness, drowsiness, fatigue, fever, headache, pseudotumor cerebri, psychotic reaction

Dermatologic: Alopecia, erythema multiforme, exfoliative dermatitis, pruritus, rash, Stevens-Johnson syndrome

Gastrointestinal: Abdominal pain, C. difficile -colitis, constipation, diarrhea, dyspepsia, loss of appetite, nausea (most common), pancreatitis, sore throat, vomiting

Hematologic: Agranulocytosis, aplastic anemia, eosinophilia, hemolytic anemia, methemoglobinemia, thrombocytopenia

Hepatic: Cholestasis, hepatitis, hepatic necrosis, transaminases increased, jaundice (cholestatic)

Neuromuscular & skeletal: Arthralgia, numbness, paresthesia, peripheral neuropathy, weakness

Ocular: Amblyopia, nystagmus, optic neuritis (rare)

Respiratory: Cough, dyspnea, pneumonitis, pulmonary fibrosis

Miscellaneous: Hypersensitivity (including acute pulmonary hypersensitivity), lupus-like syndrome

Overdosage/Toxicology

Symptoms of overdose include vomiting. Treatment is supportive.

Drug Interactions

Decreased effect: Antacids, especially magnesium salts, decrease absorption of nitrofurantoin; nitrofurantoin may antagonize effects of norfloxacin

Increased toxicity: Probenecid (decreases renal excretion of nitrofurantoin); anticholinergic drugs increase absorption of nitrofurantoin

Ethanol/Nutrition/Herb Interactions

Ethanol: Avoid ethanol (may increase CNS depression).

Food: Nitrofurantoin serum concentrations may be increased if taken with food.

Stability

Store at room temperature 15°C to 30°C (59°F to 86°F).

Mechanism of Action

Inhibits several bacterial enzyme systems including acetyl coenzyme A interfering with metabolism and possibly cell wall synthesis

Pharmacodynamics/Kinetics

Absorption: Well absorbed; macrocrystalline form absorbed more slowly due to slower dissolution (causes less GI distress)

Distribution: Vd: 0.8 L/kg; crosses placenta; enters breast milk

Protein binding: 60% to 90%

Metabolism: Body tissues (except plasma) metabolize 60% of drug to inactive metabolites

Bioavailability: Increased with food

Half-life elimination: 20-60 minutes; prolonged with renal impairment

Excretion:

Suspension: Urine (40%) and feces (small amounts) as metabolites and unchanged drug

Macrocrystals: Urine (20% to 25% as unchanged drug)

Dosage

Oral:

Children >1 month: 5-7 mg/kg/day in divided doses every 6 hours; maximum: 400 mg/day

UTI prophylaxis (chronic): 1-2 mg/kg/day in divided doses every 12-24 hours; maximum: 100 mg/day

Adults: 50-100 mg/dose every 6 hours

Macrocrystal/monohydrate: 100 mg twice daily

UTI prophylaxis (chronic): 50-100 mg/dose at bedtime

Dosing adjustment in renal impairment: Clcr<60 mL/minute: Contraindicated

Contraindicated in hemo- and peritoneal dialysis and continuous arteriovenous or venovenous hemofiltration

Administration

Administer with meals to slow the rate of absorption and decrease adverse effects; suspension may be mixed with water, milk, fruit juice, or infant formula

Monitoring Parameters

Signs of pulmonary reaction, signs of numbness or tingling of the extremities, periodic liver function tests

Test Interactions

False-positive urine glucose (Benedict's and Fehling's methods); no false positives with enzymatic tests

Patient Education

Inform prescriber of all prescriptions, OTC medications, or herbal products you are taking, and any allergies you have. Do not take any new medication during therapy unless approved by prescriber. Take entire prescription, even if you are feeling better. Take with food. Maintain adequate hydration (2-3 L/day of fluids) unless instructed to restrict fluid intake. If you have diabetes, drug may cause false test results with Clinitest® urine glucose monitoring; use of another type of glucose monitoring is preferable. May cause nausea or vomiting (small, frequent meals, frequent mouth care, sucking lozenges, or chewing gum may help); or diarrhea (buttermilk, boiled milk, or yogurt may help). Report immediately and rash; swelling of face, tongue, mouth, or throat; or chest tightness. Report if condition being treated worsens or does not improve by the time prescription is completed.

Dental Health: Effects on Dental Treatment

No significant effects or complications reported

Dental Health: Vasoconstrictor/Local Anesthetic Precautions

No information available to require special precautions

Mental Health: Effects on Mental Status

May cause drowsiness or dizziness

Mental Health: Effects on Psychiatric Treatment

Concurrent use with anticholinergic/antiparkinsonian medications may increase the absorption of nitrofurantoin

Dosage Forms

Capsule, macrocrystal: 50 mg, 100 mg

Macrodantin®: 25 mg, 50 mg, 100 mg

Capsule, macrocrystal/monohydrate (Macrobid®): 100 mg

Suspension, oral (Furadantin®): 25 mg/5 mL (470 mL)

References

"American Academy of Pediatrics Committee on Drugs. The Transfer of Drugs and Other Chemicals Into Human Milk," Pediatrics , 2001, 108(3):776-89.

Brendstrup L, Hjelt K, Petersen KE, et al, "Nitrofurantoin Versus Trimethoprim Prophylaxis in Recurrent Urinary Tract Infections in Children," Acta Paediatr Scand , 1990. 79(12):1225-34.

Burgert SJ, Burke JP, and Box TD, "Reversible Nitrofurantoin-Induced Chronic Active Hepatitis and Hepatic Cirrhosis in a Patient Awaiting Liver Transplantation," Transplantation , 1995, 59(3):448-9.

Coraggio MJ, Gross TP, and Roscelli JD, "Nitrofurantoin Toxicity in Children," Pediatr Infect Dis J , 1989, 8(3):163-6.

D'Arcy PF, "Nitrofurantoin," Drug Intell Clin Pharm , 1985, 19(7-8):540-7.

Penn RG and Griffin HP, "Adverse Reactions to Nitrofurantoin in the United Kingdom, Sweden, and Holland," Br Med J (Clin Res Ed) , 1982, 284(6327):1440-2.

"Practice Parameter: The Diagnosis, Treatment, and Evaluation of the Initial Urinary Tract Infection in Febrile Infants and Young Children. American Academy of Pediatrics. Committee on Quality Improvement. Subcommittee on Urinary Tract Infection," Pediatrics , 1999, 103(4 Pt 1):843-52.

International Brand Names

Apo-Nitrofurantoin® (CA, SG); Furabid® (NL); Furadantina® (AR, CL); Furadantin® (AT, CH, DE, GB, IE, IN, IT, NO, NZ, SE, ZA); Furadantine® (BE, FR, LU, NL); Furadantin Suspension® (AU); Furadoïne® (FR); Furadonin® (RU); Furantoina® (DO, ES, GT, HN, SV); Furantoin Leciva® (CZ); Furedan® (IT); Furil® (IT); Furobactina® (ES); MacroBID® (CA); Macrobid® (GB); Macrodantina® (BR, CL, CO, MX); Macrodantin® (AU, CA, GB, HK, IE, IT, ZA); Macrodin® (CY); Macrosan® (CL); Microdoïne® (FR); Neo-Furadantin® (IT); Nephrotoin® (BD); Nifuran® (NZ); Nifurantin® (CZ, DE, IL); Nifuratio® (PL); Nifuretten® (DE); Ninur® (HR); Nitrofurantoina® (CL, RO); Nitrofurantoin Agepha® (AT); Nitrofurantoina L.CH.® (CL); Nitrofurantoina Macro® (CL); Nitrofurantoin Dak® (DK); Nitrofurantoin® (GB, HU); Nitrofurantoin-ratiopharm® (DE, LU, PL); Nitrofurantoin SAD® (DK); Nitro Macro® (CL); Novo-Furantoin (CA); Piyeloseptyl® (TR); Ralodantin® (AU); Siraliden® (PL); Urantoin® (IL); Urodin® (CH); Uro Tablinen® (DE); Uvamin® (IL); Uvamin retard® (CH, CR, CY, EC, EG, GT, HN, JO, KW, LB, PA, SV)

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