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.

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.

The most common side effects noted with nitrofurantoin 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 physicians 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 nitrofurantoin for the first time. Symptoms include difficult breathing chills fever chest pain and cough. In other persons lung injury may occur after approximately a month of treatment. Symptoms include difficult breathing rapid breathing and cough. Fortunately the symptoms usually resolve within a week if the medication is stopped. In still other persons lung injury may not develop until after several months or years of therapy. Unless it is recognized and treated this delayed lung injury can result in 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 the arms and legs may occur with nitrofurantoin therapy most commonly causing tingling in the extremities. The condition can become severe and is more likely to occur in patients with diabetes mellitus vitamin B deficiency or general debilitation.

A type of anemia reduced red blood cell count called hemolytic anemia can occur during therapy with nitrofurantoin. This reaction occurs most frequently in persons with a deficiency of an enzyme called glucose-6-phosphate dehydrogenase which is very important to the survival of red blood cells.

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

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

High doses of probenecid Benemid or sulfinpyrazone Anturane can partially block the kidneys elimination of nitrofurantoin. This can increase the blood concentrations of nitrofurantoin and the risk of toxicity from nitrofurantoin. Higher concentrations of nitrofurantoin also can occur with the use of medications that slow the rate of stomach emptying. Such drugs include propantheline Probanthine dicyclomine Bentyl and bethanechol Urecholine.

Nitrofurantoin is used to treat or prevent urinary tract infections.

All formulations should be kept at room temperature 15-30°C 59-86°F.