Furadantin

Dosage Forms & Strengths

capsule, macrocrystals

• 25mg
• 50mg
• 100mg

capsule, monohydrate/macrocystals

• 100 mg

oral suspension

• 25mg/5mL

Urinary Tract Infection

Susceptible strains of Escherichia coli, Enterobacter spp, Klebsiella spp, Staphylococcus aureus, and S saprophyticus

Macrocrystals (Macrodantin, Furadantin, and equivalents): 50-100 mg PO q6hr for 7 days or for 3 days after obtaining sterile urine

Monohydrate/macrocrystals (Macrobid and equivalents): 100 mg PO q12hr for 7 days or for 3 days after obtaining sterile urine

Long-term prophylaxis/suppression: 50-100 mg macrocrystals PO HS for up to 12 months

Dosing Considerations

Avoid for long-term UTI suppression; possible pulmonary toxicity; safer alternatives are available

Not drug of choice in elderly because of unfavorable side-effect profile

Loses effectiveness in patients with CrCl <60 mL/min due to inadequate urine concentration (Beers criteria)

Monitor renal function; renally excreted; decreased renal function more likely in elderly

Monitor liver function and possible pulmonary reactions

Take with food or milk

Dual release macrocrystals indicated only for patients >12 years for acute UTIs (cystitis) caused by E coli or S saprophyticus

Dosage Forms & Strengths

capsule, macrocrystals

• 25mg
• 50mg
• 100mg

capsule, monohydrate/macrocrystals

• 100 mg

oral suspension

• 25mg/5mL

Urinary Tract Infection

>1 month

• 5-7 mg/kg/day PO divided q6hr for 7 days
• UTI prophylaxis: 1-2 mg/kg PO qHS or 2 divided doses

>12 years

• Macrocrystals (Macrodantin, Furadantin, and equivalents): 50-100 mg PO q6hr for 7 days or for 3 days after obtaining sterile urine
• Monohydrate/macrocrystals (Macrobid and equivalents): 100 mg PO q12hr for 7 days or for 3 days after obtaining sterile urine
• Long-term prophylaxis/suppression: 50-100 mg macrocrystals PO HS for up to 12 months

Dosing Considerations

Avoid for long-term UTI suppression; possible pulmonary toxicity; safer alternatives are available

Loses effectiveness in patients with CrCl <60 mL/min due to inadequate urine concentration (Beers criteria)

Monitor renal function; renally excreted; decreased renal function more likely in elderly

Monitor liver function

Take with food or milk

Dual release macrocrystals indicated only for patients >12 years for acute UTIs (cystitis) caused by E coli or S saprophyticus

Yes

• Nitrofurantoin is used to treat or prevent urinary tract infections (UTIs).

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Take Furadantin exactly as prescribed.

Furadantin is available in as an oral suspension and is given four times a day. It is recommended to take Furadantin with food.

Patients should be instructed to complete the full course of therapy; however, they should be advised to contact their physician if any unusual symptoms occur during therapy.

Shake the Furadantin suspension well before each use to mix the medication evenly. Use a dose-measuring spoon or cup to measure the correct amount of liquid for each dose; not a household spoon.

If you miss a dose, take the missed dose as soon as you remember. If it is almost time for the next dose, skip the missed dose and take your next dose at the regular time. Do not take two doses of Furadantin at the same time.

Antibiotic medicines can cause diarrhea, which may be a sign of a new infection. If you have diarrhea that is watery or has blood in it, call your doctor. Do not use any medicine to stop the diarrhea unless your doctor has told you to.

Avoid using antacids without your doctor's advice. Use only the type of antacid your doctor recommends. Some antacids can make it harder for your body to absorb nitrofurantoin.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Nitrofurantoin is used to treat urinary tract infections. This medicine is an antibiotic. It works by killing bacteria or preventing their growth. However, this medicine will not work for colds, flu, or other virus infections.

This medicine is available only with your doctor's prescription.

For all patients taking Furadantin (nitrofurantoin oral suspension):

• If you have an allergy to nitrofurantoin or any other part of this medicine.
• If you are allergic to any drugs like this one, any other drugs, foods, or other substances. Tell your doctor about the allergy and what signs you had, like rash; hives; itching; shortness of breath; wheezing; cough; swelling of face, lips, tongue, or throat; or any other signs.
• If you have kidney disease.
• If you have trouble passing urine.
• If Furadantin caused liver problems before.
• If you are more than 38 weeks pregnant.

Children:

• If your child is younger than 1 month of age. Do not give this medicine to an infant younger than 1 month of age.

This is not a list of all drugs or health problems that interact with Furadantin.

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take this medicine with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

Information for Patients

Patients should be advised to take Furadantin with food to further enhance tolerance and improve drug absorption. Patients should be instructed to complete the full course of therapy; however, they should be advised to contact their physician if any unusual symptoms should occur during therapy.

Diarrhea is a common problem caused by antibiotics which usually ends when the antibiotic is discontinued. Sometimes after starting treatment with antibiotics, patients can develop watery and bloody stools (with or without stomach cramps and fever) even as late as two or more months after having taken the last dose of the antibiotic. If this occurs, patients should contact their physician as soon as possible.

Patients should be advised not to use antacid preparations containing magnesium trisilicate while taking Furadantin.

Drug Interactions

Antacids containing magnesium trisilicate, when administered concomitantly with nitrofurantoin, reduce both the rate and extent of absorption. The mechanism for this interaction probably is adsorption of nitrofurantoin onto the surface of magnesium trisilicate.

Uricosuric drugs, such as probenecid and sulfinpyrazone, can inhibit renal tubular secretion of nitrofurantoin. The resulting increase in nitrofurantoin serum levels may increase toxicity, and the decreased urinary levels could lessen its efficacy as a urinary tract antibacterial.

Drug/laboratory Test Interactions

As a result of the presence of nitrofurantoin, a false-positive reaction for glucose in the urine may occur. This has been observed with Benedict's and Fehling's solutions but not with the glucose enzymatic test.

Carcinogenesis, Mutagenesis, Impairment of Fertility

Nitrofurantoin was not carcinogenic when fed to female Holtzman rats for 44.5 weeks or to female Sprague-Dawley rats for 75 weeks. Two chronic rodent bioassays utilizing male and female Sprague-Dawley rats and two chronic bioassays in Swiss mice and in BDF1 mice revealed no evidence of carcinogenicity.

Nitrofurantoin presented evidence of carcinogenic activity in female B6C3F1 mice as shown by increased incidences of tubular adenomas, benign mixed tumors, and granulosa cell tumors of the ovary. In male F344/N rats, there were increased incidences of uncommon kidney tubular cell neoplasms, osteosarcomas of the bone, and neoplasms of the subcutaneous tissue. In one study involving subcutaneous administration of 75 mg/kg nitrofurantoin to pregnant female mice, lung papillary adenomas of unknown significance were observed in the F1 generation.

Nitrofurantoin has been shown to induce point mutations in certain strains of Salmonella typhimurium and forward mutations on L5178Y mouse lymphoma cells. Nitrofurantoin induced increased numbers of sister chromatid exchanges and chromosomal aberrations in Chinese hamster ovary cells but not in human cells in culture. Results of the sex-linked recessive lethal assay in Drosophila were negative after administration of nitrofurantoin by feeding or by injection. Nitrofurantoin did not induce heritable mutation in the rodent models examined.

The significance of carcinogenicity and mutagenicity findings relative to the therapeutic use of nitrofurantoin in humans is unknown.

The administration of high doses of nitrofurantoin to rats causes temporary spermatogenic arrest; this is reversible on discontinuing the drug. Doses of 10 mg/kg/day or greater in healthy human males may, in certain unpredictable instances, produce a slight to moderate spermatogenic arrest with a decrease in sperm count.

Pregnancy

Pregnancy Category B

Several reproduction studies have been performed in rabbits and rats at doses up to six times the human dose and have revealed no evidence of impaired fertility or harm to the fetus due to nitrofurantoin. In a single published study conducted in mice at 68 times the human dose (based on mg/kg administered to the dam), growth retardation and a low incidence of minor and common malformations were observed. However at 25 times the human dose, fetal malformations were not observed; the relevance of these findings to humans is uncertain. There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.

Nitrofurantoin has been shown in one published transplacental carcinogenicity study to induce lung papillary adenomas in the F1 generation mice at doses 19 times the human dose on a mg/kg basis. The relationship of this finding to potential human carcinogenesis is presently unknown. Because of the uncertainty regarding the human implications of these animal data, this drug should be used during pregnancy only if clearly needed.

Labor and Delivery

See Contraindications.

Nursing Mothers

Nitrofurantoin has been detected in human breast milk in trace amounts. Because of the potential for serious adverse reactions from nitrofurantoin in nursing infants under one month of age, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother. (see CONTRAINDICATIONS)

Pediatric Use

Safety and effectiveness of Furadantin in neonates below the age of one month have not been established. (see CONTRAINDICATIONS)

Occasional incidents of acute overdosage of Furadantin have not resulted in any specific symptoms other than vomiting. Induction of emesis is recommended. There is no specific antidote, but a high fluid intake should be maintained to promote urinary excretion of the drug. It is dialyzable.

Applies to nitrofurantoin: oral capsule, oral suspension, oral tablet

Along with its needed effects, nitrofurantoin (the active ingredient contained in Furadantin) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking nitrofurantoin:

• Changes in facial skin color
• chest pain
• chills
• cough
• fever
• general feeling of discomfort or illness
• hives
• hoarseness
• itching
• joint or muscle pain
• shortness of breath
• skin rash
• sudden trouble in swallowing or breathing
• swelling of the face, mouth, hands, or feet
• troubled breathing

• Black, tarry stools
• blood in the urine or stools
• burning, numbness, tingling, or painful sensations
• dizziness
• drowsiness
• headache
• pinpoint red spots on the skin
• sore throat
• unsteadiness or awkwardness
• unusual bleeding or bruising
• unusual tiredness or weakness
• weakness in the arms, hands, legs, or feet

• Abdominal or stomach pain
• blindness
• blistering, peeling, or loosening of the skin and mucous membranes
• blue-yellow color blindness
• bluish color of the fingernails, lips, skin, palms, or nail beds
• blurred vision or loss of vision, with or without eye pain
• bulging soft spot on the head of an infant
• change in the ability to see colors, especially blue or yellow
• confusion
• cracks in the skin
• darkening of the urine
• decreased vision
• diarrhea
• diarrhea, watery and severe, which may also be bloody
• eye pain
• general tiredness and weakness
• light-colored stools
• loss of appetite
• loss of heat from the body
• mental depression
• mood or mental changes
• nausea or vomiting
• pale skin
• pale stools
• red skin lesions, often with a purple center
• red, irritated eyes
• red, swollen skin
• red, thickened, or scaly skin
• skin rash
• sores, ulcers, or white spots on the lips or in the mouth
• swollen or painful glands
• tenderness of salivary glands
• unpleasant breath odor
• upper right abdominal pain
• visual changes
• vomiting of blood
• wheezing or tightness in the chest
• yellow eyes or skin

Some side effects of nitrofurantoin may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

• Diarrhea
• gas

• Dizziness or lightheadedness
• feeling of constant movement of self or surroundings
• lack or loss of strength
• loss of hair, temporary
• sensation of spinning
• uncontrolled eye movements

-This drug is contraindicated in pregnant patients at term (38 to 42 weeks' gestation), during labor and delivery, or when the onset of labor is imminent because of the possibility of hemolytic anemia due to immature erythrocyte enzyme systems (glutathione instability). -This drug should be used during pregnancy up to 38 weeks' gestation only if the benefit outweighs the risk. AU TGA pregnancy category: A (short-term therapy) US FDA pregnancy category: B Comment: -This drug has been associated with reduced sperm counts and abnormal testicular histology in humans. Caution is recommended if use is considered in young males.

Animal studies have failed to reveal evidence of fetotoxicity or teratogenicity. There are no controlled data in human pregnancy. It is not known whether this drug can cause fetal harm or adversely affect reproductive capacity in humans. AU TGA pregnancy category A: Drugs which have been taken by a large number of pregnant women and women of childbearing age without any proven increase in the frequency of malformations or other direct or indirect harmful effects on the fetus having been observed. US FDA pregnancy category B: Animal reproduction studies have failed to demonstrate a risk to the fetus and there are no adequate and well-controlled studies in pregnant women.