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Therapeutic Classification: anti-infectives

• Prevention and treatment of urinary tract infections caused by susceptible organisms.

• Interferes with bacterial enzymes.

• Bactericidal or bacteriostatic action against susceptible organisms.

Spectrum:

• Many gram-negative and some gram-positive organisms, specifically:
  • Citrobacter,
  • Corynebacterium,
  • Enterobacter,
  • Escherichia coli,
  • Klebsiella,
  • Neisseria,
  • Salmonella,
  • Shigella,
  • Staphylococcus aureus,
  • Staphylococcus epidermidis,
  • Enterococcus.

Absorption: Readily absorbed after oral administration. Absorption is slower but more complete with macrocrystals (Macrodantin).

Distribution: Minimally distributed to tissues (concentrated in urine).

Metabolism/Excretion: Partially metabolized by the liver; 30–50% excreted unchanged by the kidneys.

Half-life: 20 min (↑ in renal impairment).

(urine levels)

Contraindicated in:

• Hypersensitivity
• Hypersensitivity to parabens (suspension)
• Oliguria, anuria, or significant renal impairment (CCr <60 mL/min)
• History of cholestatic jaundice or hepatic impairment with previous use of nitrofurantoin
• OB: Pregnancy near term (38–42 wk gestation) and during labor/delivery (↑ risk of hemolytic anemia)
• Pedi: Infants <1 mo (↑ risk of hemolytic anemia).

Use Cautiously in:

• Glucose-6-phosphate dehydrogenase (G6PD) deficiency (↑ risk of hemolytic anemia, especially in Blacks and Mediterranean and Near Eastern ethnic groups)
• Diabetes (↑ risk of neuropathy)
• OB: Use during pregnancy only if potential fetal risk outweighs potential material benefit; Lactation: May cause hemolysis in infants with G6PD deficiency who are breastfed
• Geri: Appears on Beers list. ↑ risk of pulmonary toxicity, hepatotoxicity, and peripheral neuropathy, especially with long-term use, in older adults. Avoid use in older adults if CCr <30 mL/min or for long-term suppression of urinary tract infections.

CV: chest pain.

Derm: photosensitivity.

EENT: nystagmus.

GI: anorexia, nausea, vomiting, abdominal pain, CLOSTRIDIOIDES DIFFICILE-ASSOCIATED DIARRHEA (CDAD), diarrhea, HEPATOTOXICITY.

GU: rust/brown discoloration of urine.

Hemat: blood dyscrasias, hemolytic anemia.

Neuro: dizziness, drowsiness, headache, peripheral neuropathy.

Resp: PNEUMONITIS, PULMONARY FIBROSIS.
Misc: hypersensitivity reactions.

Drug-Drug:

• Probenecid prevents high urinary concentrations; may ↓ effectiveness.
• Antacids may ↓ absorption.
• ↑risk of neurotoxicity with neurotoxic drugs.
• ↑risk of hepatotoxicity with hepatotoxic drugs.
• ↑risk of pneumonitis with drugs having pulmonary toxicity.

• PO (Adults): Treatment of active infection: 50–100 mg every 6 hr or 100 mg every 12 hr as extended-release product. Chronic suppression: 50–100 mg at bedtime.
• PO (Children >1 mo): Treatment of active infection: 5–7 mg/kg/day divided every 6 hr; maximum dose: 400 mg/day. Chronic suppression: 1–2 mg/kg/day in 1–2 divided doses; maximum dose: 100 mg/day (unlabeled).

(Generic available)

• Tablets: 50 mg; 100 mg;
• Capsules (Macrodantin): 25 mg; 50 mg; 100 mg;
• Extended-release capsules (Macrobid): 100 mg;
• Oral suspension: 25 mg/5 mL; 50 mg/5 mL;

• Assess for signs and symptoms of urinary tract infection (frequency, urgency, pain, and burning on urination; fever; cloudy or foul-smelling urine) before and periodically during therapy.
• Obtain specimens for culture and sensitivity before and during drug administration.
• Monitor intake and output ratios. Report significant discrepancies in totals.
• Monitor bowel function. Diarrhea, abdominal cramping, fever, and bloody stools should be reported to health care professional promptly as a sign of CDAD. May begin up to several wk following cessation of therapy.
• Assess for signs and symptoms of pulmonary reactions periodically during therapy. Acute reactions (fever, chills, cough, chest pain, dyspnea, pulmonary infiltration with consolidation or pleural effusion on x-ray, eosinophilia) usually occur within first wk of treatment and resolve when therapy is discontinued. Chronic reactions (malaise, dyspnea on exertion, cough, altered pulmonary function) may indicate pneumonitis or pulmonary fibrosis and are more common in patients taking nitrofurantoin for 6 mo or longer.

• Monitor CBC routinely with patients on prolonged therapy.
  • Monitor liver function tests periodically during therapy. May cause ↑ serum glucose, bilirubin, and alkaline phosphatase. If hepatotoxicity occurs, discontinue therapy.
  • Monitor renal function periodically during therapy. May cause ↑ BUN and serum creatinine.

• PO: Take with meals to improve absorption and ↓ adverse effects.
  • DNC: Do not crush tablets or open capsules (Macrobid).
  • Macrodantin may be opened and mixed with food or juice for immediate use.
  • Administer liquid preparations with calibrated measuring device. Shake well before administration. Oral suspension may be mixed with water, milk, fruit juices, or infant formula. Rinse mouth with water after administration of oral suspension to avoid staining teeth.

• Explain purpose and side effects of medication to patient. Advise patient to read Patient Information before starting therapy. Instruct patient to take medication around the clock, as directed. Take missed doses as soon as remembered and space next dose 2–4 hr apart. Do not skip or double up on missed doses. Instruct patient to consult health care professional if no improvement is seen within a few days after initiation of therapy.
• May cause dizziness or drowsiness. Caution patient to avoid driving or other activities requiring alertness until response to medication is known.
• Inform patient that medication may cause a rust-yellow to brown discoloration of urine, which is not significant.
• Advise patient to notify health care professional if fever, chills, cough, chest pain, dyspnea, skin rash, numbness or tingling of the fingers or toes, or intolerable GI upset occurs. Signs of superinfection (milky, foul-smelling urine; perineal irritation; dysuria) should also be reported.
• Instruct patient to notify health care professional if fever and diarrhea develop, especially if stool contains blood, pus, or mucus. Advise patient not to treat diarrhea without consulting health care professional.
• May cause fetal harm. Advise females of reproductive potential to notify health care professional if pregnancy is planned or suspected and to avoid breastfeeding during therapy and for 1 mo after last dose of therapy. May cause hemolytic anemia in pregnant patients at term (38–42 wk gestation), during labor and delivery, or when the onset of labor is imminent.

• Resolution of the signs and symptoms of infection. Therapy should be continued for a minimum of 7 days and for at least 3 days after the urine has become sterile.
• Decrease in the frequency of infections in chronic suppressive therapy.

Furadantin, Macrobid, Macrodantin