nitrofurantoin, Macrodantin, Furadantin, Macrobid (cont.)

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DRUG INTERACTIONS: 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.

Concomitant administration of a magnesium trisilicate antacid may decrease the absorption of nitrofurantoin, reducing the effectiveness of nitrofurantoin.

In laboratory tests, nitrofurantoin reduced the effect of quinolone antibiotics, for example, norfloxacin (Noroxin). Therefore, nitrofurantoin should not be combined with quinolone antibiotics.

PREGNANCY: Although there are no adequate studies of nitrofurantoin in pregnant women, many women have safely used it during pregnancy; however, nitrofurantoin should not be used near the time of delivery (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: Common side effects include headache, rash, itching, nausea, vomiting, loss of appetite, diarrhea, and abdominal pain. The macrocrystalline form (Macrodantin) appears to cause less stomach upset. Stomach upset also can be minimized by using a lower dose or by taking nitrofurantoin with food or milk.

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 difficulty breathing, chills, fever, chest pain, and cough. In other persons, lung injury may occur after approximately a month of treatment. Symptoms include difficulty 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.

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