Medications and Drugs
Pharmacy Author: Omudhome Ogbru, PharmD
Medical and Pharmacy Editor: Jay W. Marks, MD
GENERIC NAME: nitrofurantoin
BRAND NAMES: Macrodantin, Furadantin, Macrobid
DRUG CLASS AND MECHANISM: Nitrofurantoin is an antibiotic that is used for
treating urinary tract infections caused by several types of bacteria. It is
effective against E. Coli, Enterobacter cystitis, Enterococcus, Klebsiella,
and Staphylococcus aureus. Nitrofurantoin interferes with the production of
bacterial proteins, DNA, and cell walls. Bacteria cannot survive without a cell
wall or multiply without DNA. Three forms are available: 1) a microcrystalline form
(Furadantin), 2) a macrocrystalline form (Macrodantin), and 3) 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. The FDA approved nitrofurantoin
in 1953.
PRESCRIPTION: Yes
GENERIC AVAILABLE: Yes
PREPARATIONS: Capsules: 25, 50, 75, and 100 mg. Oral suspension: 25 mg/5 ml.
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: The recommended adult dose for treating urinary tract infections is
50-100 mg 4 times daily (Macrodantin, Furadantin) or 100 mg every 12 hours
(Macrobid). 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. 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) 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.
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
- Drug Interactions - Learn about potential drug interactions you may be exposed to. Drug interactions can occur with prescription drugs, OTC medication, vitamins, herbs, and supplements.
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