Nitrofurantoin

Pronunciation: nye-troe-FYOOR-an-toyn
Class: Nitrofuran

Trade Names

Furadantin
- Oral suspension 25 mg per 5 mL

Macrobid
- Capsules 100 mg (as monohydrate/macrocrystals)

Macrodantin
- Capsules 25 mg
- Capsules 50 mg
- Capsules 100 mg

Pharmacology

May interfere with bacterial cell wall formation and bacterial duplication. Inhibits bacterial carbohydrate metabolism. Bacteriostatic in low concentrations; bactericidal at higher concentrations.

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Pharmacokinetics

Absorption

Nitrofurantoin is well absorbed from the GI tract, macrocrystalline form is absorbed more slowly, and food increases bioavailability.

Distribution

Nitrofurantoin protein binding is approximately 60%.

Metabolism

Approximately 50% to 70% of nitrofurantoin is rapidly metabolized by body tissues.

Elimination

Nitrofurantoin is eliminated in urine (30% to 50% unchanged). The t _½ in healthy patients is 20 min, and the t _½ in anephric patients is 60 min.

Special Populations

Nitrofurantoin accumulates in serum.

Indications and Usage

Treatment of UTI caused by susceptible strains of Escherichia coli , enterococci , Staphylococcus aureus , certain strains of Klebsiella and Enterobacter species.

Contraindications

Renal function impairment (CrCl less than 60 mL/min); anuria or oliguria; pregnant women at term; infants younger than 1 mo of age.

Dosage and Administration

PO 50 to 100 mg 4 times daily with meals for 7 days minimum and for at least 3 days after sterile urine is obtained. Monohydrate microcrystals: 100 mg every 12 h for 7 days.

PO 5 to 7 mg/kg/24 h in 4 divided doses with meals and at bedtime for minimum of 7 days and for at least 3 days after sterile urine is obtained.

PO 50 to 100 mg at bedtime.

PO 1 mg/kg per 24 h as a single or 2 divided doses.

General Advice

• Administer with food to improve absorption and tolerability.
• Shake oral suspension well before measuring dose.

Storage/Stability

Store capsules at controlled room temperature (59° to 86°F). Store oral suspension at controlled room temperature (68° to 77°F). Protect from freezing.

Drug Interactions

Increased absorption of nitrofurantoin.

May reduce anti-infective action by decreasing absorption.

May increase nitrofurantoin serum levels by reducing renal elimination.

Laboratory Test Interactions

Urinary creatinine elevation and false-positive urine glucose determination with Benedict reagent (copper sulfate solution) may occur.

Adverse Reactions

Cardiovascular

ECG changes.

CNS

Dizziness; drowsiness; headache; malaise; nystagmus; peripheral neuropathy.

Dermatologic

Alopecia; angioedema; erythema multiforme; exfoliative dermatitis; maculopapular, erythematous, or eczematous eruption; photosensitivity; pruritus; urticaria.

EENT

Optic neuritis (postmarketing).

GI

Abdominal pain; anorexia; diarrhea; emesis; flatulence; nausea; parotiditis; pancreatitis; pseudomembranous colitis.

Hematologic

Agranulocytosis; aplastic anemia; decreased hemoglobin; eosinophilia; granulocytopenia; hemolytic anemia from G-6-PD deficiency; leukopenia; megaloblastic anemia; thrombocytopenia.

Hepatic

Cholestatic jaundice; chronic active hepatitis; hepatic necrosis; hepatitis; hepatotoxicity; increased AST and ALT; increased bilirubin and alkaline phosphatase; jaundice; permanent liver dysfunction.

Metabolic

Increased serum phosphorous.

Respiratory

Acute, subacute, or chronic pulmonary reaction (eg, shortness of breath, chest pain, cough, fever, chills); permanent pulmonary impairment.

Miscellaneous

Allergic reactions (including lupus-like syndrome); anaphylaxis; arthralgia; asthmatic attack in patient with history of asthma; benign intracranial hypertension; drug fever; muscular aches; sialadenitis; superinfection.

Precautions

Pregnancy

Category B . Contraindicated in women at term. Do not give to pregnant patient with G-6-PD deficiency.

Lactation

Excreted in breast milk.

Children

Contraindicated in infants younger than 1 mo of age. Monohydrate microcrystals: Safety and efficacy not established in children younger than 12 yr of age.

Superinfection

Prolonged or repeated therapy with antibiotics may result in overgrowth of nonsusceptible bacteria or fungi.

Hemolysis

Hemolytic anemia has occurred, apparently linked to G-6-PD deficiencies. Discontinue at any sign of hemolysis.

Peripheral neuropathy

May become severe or irreversible; fatalities have been reported. Predisposing conditions such as renal function impairment, anemia, diabetes, electrolyte imbalance, vitamin B deficiency, and debilitating diseases may increase risk.

Pseudomembranous colitis

Consider in patients who develop diarrhea.

Pulmonary reactions

Acute and chronic reactions, including interstitial pneumonia, respiratory failure and death, have occurred. Do not give to any patient who has had pulmonary reaction to drug.

Overdosage

Symptoms

Vomiting.

Patient Information

• Remind patient to shake nitrofurantoin suspension before measuring dose.
• Instruct patient to take medication with food or milk.
• Inform patient to expect urine to be orange or brown in color while taking medication.
• Teach patient importance of completing full course of antibiotic to avoid recurrent infection.
• Instruct patient to report the following symptoms to health care provider: shortness of breath, difficulty breathing, changes in urination (other than orange discoloration), nausea, vomiting, diarrhea, cramping, skin changes, chest pain, cough, fever, headache, dizziness, vision changes, unusual bleeding (ie, red or black urine or stool), yellowing of skin, light-colored stools or edema.
• Caution patient to avoid exposure to sunlight and to use sunscreen or wear protective clothing to avoid photosensitivity reaction.

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