What Factors Affect a Sufficient Nitrofurantoin Dose?

Canaan Downs
Canaan Downs
Common side effects of nitrofurantoin include headache, diarrhea, and easy bruising.
Common side effects of nitrofurantoin include headache, diarrhea, and easy bruising.

Nitrofurantoin is an antibiotic generally used in the treatment of preventing cystitis, also known as urinary tract infection. Due to the serious side effects associated with its use, it is generally recommended only when an infection has not responded to treatment with other antibiotics. Pediatric patients should be given a significantly lower nitrofurantoin dose than is recommended for adults, as should patients with decreased liver function.

When using this medication to treat cystitis, the standard initial adult nitrofurantoin dose is 50 to 100 mg administered orally four times daily. The dual release nitrofurantoin dose is 100 mg given twice daily in adults, as is also recommended for children over the age of 12. Younger children should be given 5 to 7 mg per kg of body weight, up to 400 mg daily in four divided doses. Therapy can be stopped after seven days or at least three days after the urine becomes sterile.

Nitrofurantoin is also used on occasion for the prevention of cystitis in patients who have had several recurrences of cystitis or for whom the development of cystitis may produce additional health complications. Given prophylactically, a nitrofurantoin dose of between 50 and 100 mg taken at bedtime should be sufficient. In children, a dose of 1 to 2 mg per kg of body weight up to a maximum daily dose of 100 mg each day can be given in one or two divided doses.

Patients suffering from diminished hepatic function may need to be given a lower nitrofurantoin dose, as the drug is heavily metabolized in the liver. Due to the risk of toxicity, alternatives to this medication should be considered in patients with reduced kidney function, anuria, or oliguria. Since elderly patients are at increased risk of this and other side effects, alternative medications should be used in geriatric populations.

Other risks of nitrofurantoin include the development of hemolytic anemia, making the medication unsuitable in pregnant mothers or in infants younger than one month old. Patients with a history of liver damage, hepatitis, or chostestatic jaundice should not take this medication, as a number of deaths have been reported in these populations. All patients taking nitrofurantoin should be given regular liver enzyme tests during the course of therapy. Patients taking nitrofurantoin for a long period of time, particularly those with anemia, diabetes, vitamin B deficiency, electrolyte imbalance, or debility are also at risk for irreversible or fatal peripheral nerve damage. Chronic use of nitrofurantoin is also associated with an increased risk of pulmonary dysfunction, in particular pulmonary fibrosis or interstitial pneumonitis, and should be regularly monitored.

Like most antibiotics, therapy with nitrofurantoin may result in Clostridium difficile associated diarrhea. While generally mild, this condition has the potential to be life threatening. If the discontinuation of therapy does not result in the reduction of symptoms, more serious interventions may be needed.

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    • Common side effects of nitrofurantoin include headache, diarrhea, and easy bruising.
      Common side effects of nitrofurantoin include headache, diarrhea, and easy bruising.