Detailed Drug Information:

DRUG CLASS AND MECHANISM: Nitrofurantoin is an anti-bacterial that is used to treat urinary tract infections caused by many gram-negative and some gram-positive bacteria. Three forms are available: a microcrystalline form (Furadantin), a macrocrystalline form (Macrodantin), and a sustained release macrocrystalline form used twice daily (Macrobid). The macrocrystalline form is more slowly absorbed than the microcrystalline form and is useful for patients who cannot tolerate the microcrystalline form. Nitrofurantoin interferes with the bacterial metabolism of carbohydrate and also disrupts the formation of the bacterial cell wall. Nitrofurantoin was approved by the FDA in 1953.

PREPARATIONS: Capsules (Macrodantin): 25mg, 50mg, 100mg.Sustained-release capsules (Macrobid): 100 mg. Tablets (Furadantin): 50mg, 100mg. Oral suspension (Furadantin): 50mg per teaspoonful.

STORAGE: All formulations should be kept at room temperature, 15-30°C (59-86°F).

PRESCRIBED FOR: Nitrofurantoin is used to treat or prevent urinary tract infections.

DOSING: Nitrofurantoin can be taken with or without meals. Taking it with meals increases its absorption into the body. The suspension can be mixed with water, milk, juice, or infant formula. Except for the sustained-release product (Macrobid), nitrofurantoin usually is given 4 times daily to treat urinary tract infections. It also is used once a day (or in some children, twice daily) to prevent urinary tract infections. It should not be used in persons with poor kidney function.

DRUG INTERACTIONS: High doses of probenecid (Benemid) orsulfinpyrazone (Anturane) can partially block the kidney's elimination ofnitrofurantoin. This can increase the blood concentrations ofnitrofurantoin and the risk of toxicity from nitrofurantoin. Higher concentrations of nitrofurantoin also can occur with the use ofmedications that slow the rate of stomach emptying. Such drugs include propantheline (Probanthine), dicyclomine (Bentyl), and bethanechol (Urecholine).

PREGNANCY: Although there are no adequate studies ofnitrofurantoin in pregnant women, many women have used it duringpregnancy, and it has proved to be safe. Studies in animals suggest no important effects on the fetus. Nitrofurantoin, therefore, can be used in pregnancy if the physician feels that it is necessary. However, nitrofurantoin should not be used near term (38-42 weeks gestation) since it interferes with the immature enzyme systems in the red blood cells of newborns, damaging the cells and resulting in anemia.

NURSING MOTHERS: Nitrofurantoin is distributed into breast milk and should be used with caution in women who are breast-feeding.

SIDE EFFECTS: The most common side effects noted withnitrofurantoin are gastrointestinal, including nausea, vomiting, loss of appetite, diarrhea, and abdominal pain. The macrocrystalline form (Macrodantin) appears to cause fewer side effects. The side effects also can be minimized by using a lower dose (with the physician's consent) or by taking the drug with food or milk. Headache is the most common nervous system effect.

Nitrofurantoin can cause serious lung injury. The reaction can occur within hours of the start of treatment if the patient has previously received nitrofurantoin or within a few days of starting nitrofurantoinfor the first time. Symptoms include difficult breathing, chills, fever,chest pain, and cough. In other persons, lung injury may occur afterapproximately a month of treatment. Symptoms include difficult breathing,rapid breathing, and cough. Fortunately, the symptoms usually resolvewithin a week if the medication is stopped. In still other persons, lunginjury may not develop until after several months or years of therapy.Unless it is recognized and treated, this delayed lung injury can resultin permanent lung damage that remains even after the drug is stopped.

Allergic skin reactions also can occur, including some which are severe.

A condition known as peripheral neuropathy (damage to the nerves of thearms and legs), may occur with nitrofurantoin therapy, most commonlycausing tingling in the extremities. The condition can become severe andis more likely to occur in patients with diabetes mellitus, vitamin Bdeficiency or general debilitation.

A type of anemia (reduced red blood cell count) called hemolytic anemiacan occur during therapy with nitrofurantoin. This reaction occurs mostfrequently in persons with a deficiency of an enzyme calledglucose-6-phosphate dehydrogenase which is very important to the survivalof red blood cells.

Nitrofurantoin also can cause liver damage leading to jaundice or a formof hepatitis which can be fatal. Elevated liver enzymes indicate liverdamage and are a reason to stop the drug.

Treatment with nitrofurantoin can cause urine to change color to a darkyellow or brown.