Nitrofurantoin

Indications

Nitrofurantoin is used for: Uncomplicated UTI, Urinary Tract Infection

Adult Dose

Oral Acute uncomplicated urinary tract infections Adult: 50-100 mg 4 times daily for 7 days or for 3 days after obtaining sterile urine. SR preparation: 100 mg bid for 7 days or for 3 days after obtaining sterile urine. Prophylaxis of uncomplicated urinary tract infections Adult: 50-100 mg at bedtime for up to 12 months.

Child Dose

Urinary Tract Infection >1 month 5-7 mg/kg/day PO divided q6hr for 7 days UTI prophylaxis: 1-2 mg/kg PO qHS or 2 divided doses >12 years 50-100 mg PO q6hr for 7 days or for 3 days after obtaining sterile urine SR preparation: 100 mg PO q12hr for 7 days or for 3 days after obtaining sterile urine Long-term prophylaxis/suppression: 50-100 mg PO at bedtime for up to 12 months

Renal Dose

Loses effectiveness in patients with CrCl <60 mL/min due to inadequate urine concentration Monitor renal function; renally excreted; decreased renal function more likely in elderly

Administration

Should be taken with food. Take w/ or immediately after meals. Sustained release macrocrystals indicated only for patients >12 years for acute UTIs (cystitis) caused by E coli or S saprophyticus

Contra Indications

Severe renal impairment (anuria, oliguria, significantly elevated serum creatinine, CrCl <60 ml/min). Hypersensitivity to nitrofurans, G6PD deficiency, infants <3 mth. Pregnancy at term, during labour and delivery, or when the onset of labour is imminent.

Precautions

Elderly. Monitor hepatic and pulmonary function during prolonged therapy. Pre-existing pulmonary, hepatic, neurological, or allergic disorders, predisposition to peripheral neuropathy e.g. renal impairment, anaemia, DM, electrolyte imbalance, debility, vitamin B deficiency. Withdraw if signs of peripheral neuropathy occur. Lactation. Lactation: Enters breast milk; discontinue drug or do not nurse

Pregnancy-Lactation

Interactions

Reduced excretion with probenecid or sulfinpyrazone. Absorption reduced by magnesium trisilicate. Antagonistic effects with quinolone antibacterials. Reduced effects with carbonic anhydrase inhibitors or urinary alkalinisers.

Adverse Effects

Side effects of Nitrofurantoin : Nausea, vomiting, anorexia, abdominal pain, diarrhoea; headache, drowsiness, vertigo, dizziness, nystagmus, benign intracranial hypertension; rash, urticaria, pruritus, fever, sialadenitis, angioedema, erythema multiforme, exfoliative dermatitis, pancreatitis, lupus-like syndrome, myalgia, arthralgia; acute pulmonary sensitivity reactions; megaloblastic anaemia, leucopenia, granulocytopenia or agranulocytosis, thrombocytopenia, aplastic anaemia, haemolytic anaemia (in G6PD-deficient patients); transient alopecia; brownish discolouration of urine. Potentially Fatal: Peripheral polyneuropathy, hepatotoxicity, anaphylaxis, Stevens-Johnson syndrome, interstitial pneumonitis, pulmonary fibrosis.

Mechanism of Action

Nitrofurantoin interferes with cell metabolism and cell wall synthesis by inhibiting several enzyme systems including acetyl coenzyme A. It is bactericidal to most gram-positive and gram-negative urinary tract pathogens.