|Trade names||Macrobid, Macrodantin and others|
|Elimination half-life||20 minutes|
|Excretion||urine and bile|
|CompTox Dashboard (EPA)|
|Chemical and physical data|
|Molar mass||238.16 g·mol−1|
|3D model (JSmol)|
|Melting point||270 to 272 °C (518 to 522 °F) (decomp.)|
|(what is this?)|
Common side effects include nausea, loss of appetite, diarrhea, and headaches. Rarely numbness, lung problems, or liver problems may occur. It should not be used in people with kidney problems. While it appears to be generally safe during pregnancy it should not be used near delivery. While it usually works by slowing bacterial growth, it may result in bacterial death at the high concentrations found in urine.
Nitrofurantoin was first sold in 1953. It is on the World Health Organization's List of Essential Medicines, the safest and most effective medicines needed in a health system. It is available as a generic medication. The wholesale cost in the developing world is between 0.10 and 9.20 USD for a course of treatment. In the United States, the wholesale cost is about 8 USD for this amount as of 2018. In 2016 it was the 186th most prescribed medication in the United States with more than three million prescriptions.
Increasing bacterial antibiotic resistance to other commonly used agents, such as fluoroquinolones and trimethoprim/sulfamethoxazole, has led to increased interest in using nitrofurantoin. The efficacy of nitrofurantoin in treating UTIs combined with a low rate of bacterial resistance to this agent makes it one of the first-line agents for treating uncomplicated UTIs as recommended by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases.
Nitrofurantoin has been shown to have good activity against:
- E. coli
- Staphylococcus saprophyticus
- Coagulase negative staphylococci
- Enterococcus faecalis
- Staphylococcus aureus
- Streptococcus agalactiae
- Citrobacter species
- Klebsiella species
- Bacillus subtilis species
It is used in the treatment of infections caused by these organisms.
Many or all strains of the following genera are resistant to nitrofurantoin:
Antibiotic susceptibility testing should always be performed to further elucidate the resistance profile of the particular strain of bacteria causing infection.
Nitrofurantoin is pregnancy category B in the United States and pregnancy category A in Australia. It is one of the few drugs commonly used in pregnancy to treat UTIs. It however should not be used in late pregnancy due to the potential risk of hemolytic anemia in the newborn. Newborns of women given this drug late in pregnancy had a higher risk of developing neonatal jaundice.
Evidence of safety in early pregnancy is mixed as of 2017. The American College of Obstetricians and Gynecologists states that while they can be used in the first trimester other options may be preferred. They remain a first line treatment in the second trimester. A 2015 meta analysis found no increased risk from first trimester use in cohort studies that was a slight increase of malformations in case control studies.
The most common side effects with nitrofurantoin are nausea, headache, and flatulence. Less common adverse events (occurring in less than 1% of those taking the drug) include:
- Gastrointestinal: diarrhea, dyspepsia, abdominal pain, constipation, emesis
- Neurologic: dizziness, drowsiness, amblyopia
- Respiratory: acute pulmonary hypersensitivity reaction
- Allergic: pruritus, urticaria
- Dermatologic: hair loss
- Miscellaneous: fever, chills, malaise
Patients should be informed that nitrofurantoin colours urine brown; this is completely harmless.
Some of the more serious but rare side effects of nitrofurantoin have been a cause of concern. These include pulmonary reactions, hepatotoxicity, and neuropathy.
The pulmonary toxicity caused by nitrofurantoin can be categorized into acute, subacute, and chronic pulmonary reactions. The acute and subacute reactions are thought to be due to a hypersensitivity reaction and often resolve when the drug is discontinued. Acute reactions have been estimated to occur in about one in 5000 women who take the drug. These reactions usually develop 3–8 days after the first dose of nitrofurantoin, but may occur from a few hours to a few weeks after starting the drug. Symptoms include fever, dyspnea, chills, cough, pleuritic chest pain, headache, back pain, and epigastric pain. Chest radiograph will often show unilateral or bilateral infiltrates similar to pulmonary edema. Treatment includes discontinuation of the nitrofurantoin, which should result in symptom improvement within 24 hours.
Chronic pulmonary reactions caused by nitrofurantoin include diffuse interstitial pneumonitis, pulmonary fibrosis, or both. This uncommon reaction may occur 1 month to 6 years after starting the drug and is usually related to its total lifetime dose. This reaction manifests with progressive shortness of breath. It is important to recognize nitrofurantoin as possible cause of symptoms and discontinue the drug when the suspicion of pulmonary side effects arises as it can be reversible if the drug is stopped early.
Hepatic reactions, including hepatitis, cholestatic jaundice, chronic active hepatitis, and hepatic necrosis, occur rarely. The onset of chronic active hepatitis may be insidious, and patients should be monitored periodically for changes in biochemical tests that would indicate liver injury. These reactions usually occur after exposure to the drug for more than 6 weeks. If signs of liver failure are observed in a patient taking nitrofurantoin, the drug should be discontinued. Re-challenge with the drug at a later date is not recommended, as the reaction may have a hypersensitivity component and recur when the drug is resumed.
Neuropathy is a rare side effect of taking nitrofurantoin. Patients may experience numbness and tingling in a stocking-glove pattern, which may or may not improve upon discontinuation of the drug.
Nitrofurantoin is contraindicated in patients with decreased renal function (CrCl < 60 ml/min) due to systemic accumulation and subtherapeutic levels reached in the urinary tract. However, a retrospective chart review suggests the data for this cutoff are slim and a cutoff of CrCl < 40 ml/min would be more appropriate. Many of the severe side effects of this drug are more common in the elderly and those with renal impairment, as this causes the drug to be retained in the body and reach higher systemic levels. Thus, the drug is not recommended for the elderly population according to 2012 AGS Beers criteria.
Nitrofurantoin is also contraindicated in babies up to the age of one month, as they have immature enzyme systems in their red blood cells (glutathione instability), so nitrofurantoin must not be used because it can cause haemolytic anaemia. For the same reason, nitrofurantoin should not be given to pregnant women after 38 weeks of pregnancy. Nitrofurantoin is contraindicated in patients with glucose-6-phosphate dehydrogenase deficiency (G6PD) because of risk of intravascular hemolysis resulting in anemia.
Organisms are said to be susceptible to nitrofurantoin if their minimum inhibitory concentration is 32 μg/ml or less. The peak blood concentration of nitrofurantoin following an oral dose of nitrofurantoin 100 mg, is less than 1 μg/ml and may be undetectable. Its bioavailability is about 90% and the urinary excretion is 40%[full citation needed] tissue penetration is negligible; the drug is well concentrated in the urine: 75% of the dose is rapidly metabolised by the liver, but 25% of the dose is excreted in the urine unchanged, reliably achieving levels of 200 μg/ml or more. In studies of dogs, the majority of urinary excretion is through glomerular filtration with some tubular secretion. There is also tubular absorption which is increased with urine acidification. However the activity of nitrofurantoin is also pH dependent and mean inhibitory concentration rises sharply with increased pH above 6. Nitrofurantoin cannot be used to treat infections other than simple cystitis.
Resistance to nitrofurantoin may be chromosomal or plasmid-mediated and involves inhibition of nitrofuran reductase. Acquired resistance in E. coli continues to be rare.
Nitrofurantoin and its metabolites are excreted mainly by the kidneys. In renal impairment, the concentration achieved in urine may be subtherapeutic. Nitrofurantoin should not be used in patients with a creatinine clearance of 60 ml/min or less. However, a retrospective chart review may suggest nitrofurantoin is not contraindicated in this population.
There are two formulations of nitrofurantoin.
- Macrocrystals - (Macrodantin, Furadantin) - 25, 50, or 100 mg capsules - taken once every 6 hours
- Monohydrate/macrocrystals - (Macrobid) - 100 mg capsules - taken once every 12 hours or 2 times a day (written on prescriptions as BID, which is the last part of the trade name MacroBID). It is 75% monohydrate and 25% macrocrystals.
Mechanism of action
Nitrofurantoin is concentrated in the urine, leading to higher and more effective levels in the urinary tract than in other tissues or compartments. With a 100 mg oral dose, plasma levels are typically less than 1 µg/ml while in the urine it reaches 200 µg/ml.
The mechanism of action is unique and complex. The drug works by damaging bacterial DNA, since its reduced form is highly reactive. This is made possible by the rapid reduction of nitrofurantoin inside the bacterial cell by flavoproteins (nitrofuran reductase) to multiple reactive intermediates that attack ribosomal proteins, DNA, respiration, pyruvate metabolism and other macromolecules within the cell. Nitrofurantoin exerts greater effects on bacterial cells than mammalian cells because bacterial cells activate the drug more rapidly. It is not known which of the actions of nitrofurantoin is primarily responsible for its bactericidal activity. The broad mechanism of action for this drug likely is responsible for the low development of resistance to its effects, as the drug affects many different processes important to the bacterial cell.
Residues from the breakdown of nitrofuran veterinary antibiotics, including nitrofurantoin, have been found in chicken in Vietnam, China, Brazil, and Thailand. The European Union banned the use of nitrofurans in food producing animals by classifying it in ANNEX IV (list of pharmacologically active substances for which no maximum residue limits can be fixed) of the Council Regulation 2377/90. The Food and Drug Administration (FDA) of the United States has prohibited furaltadone since February 1985 and withdrew the approval for the other nitrofuran drugs (except some topical uses) in January 1992. The topical use of furazolidone and nitrofurazone was prohibited in 2002. Australia prohibited the use of nitrofurans in food production in 1992. Japan did not allocate MRLs for nitrofurans leading to the implementation of a "zero tolerance or no residue standard". In Thailand, the Ministry of Health issued in 2001 Proclamation No. 231 MRL of veterinary drug in food which did not allocate MRL for nitrofurans. The Ministry of Agriculture and Cooperatives had already prohibited importation and use of furazolidone and nitrofurazone in animal feed in 1999 which was extended to all nitrofurans in 2002. Several metabolites of nitrofurans, such as furazolidone, furaltadone and nitrofurazone cause cancer or genetic damage in rats.
Society and culture
It is available as a generic medication. The wholesale cost in the developing world is between 0.10 and 9.20 USD for a course of treatment. In the United States, the wholesale cost is about 8 USD for this amount as of 2018.
The cost of the liquid formulation of nitrofurantoin in the U.S. became controversial after a 400% price increase. There are two manufacturers of the liquid formulation in the U.S., Casper Pharma and Nostrum Laboratories. In 2018, Casper increased their price to $2,800. In response to Casper, Nostrum increased their price from $474.75 to $2,392. In the U.K., a slightly larger bottle costs £446.95. In an interview with the Financial Times, Nirmal Mulye, Nostrum chief executive, said that there was a "moral requirement to sell the product at the highest price." He defended Martin Shkreli, and said, "This is a capitalist economy and if you can’t make money you can’t stay in business." Mulye also attacked the U.S. Food and Drug Administration as "incompetent and corrupt." There is a shortage of liquid nitrofurantoin, because the FDA implemented new rules on impurities, he said. Mulye dismissed the new rules on impurities as a "piece of nonsense."
FDA commissioner Scott Gottlieb tweeted a response: "[T]here’s no moral imperative to price gouge and take advantage of patients. FDA will continue to promote competition so speculators and those with no regard to public health consequences can’t take advantage of patients who need medicine."
Nitrofurantoin is marketed under many names in countries worldwide.
- "Nitrofurantoin". The American Society of Health-System Pharmacists. Archived from the original on 2015-07-07. Retrieved Aug 1, 2015.
- "Prescribing medicines in pregnancy database". Australian Government. 3 March 2014. Archived from the original on 8 April 2014. Retrieved 22 April 2014.
- Blass, Benjamin (2015). Basic Principles of Drug Discovery and Development. Elsevier. p. 511. ISBN 9780124115255. Archived from the original on 2017-09-08.
- World Health Organization (2019). World Health Organization model list of essential medicines: 21st list 2019. Geneva: World Health Organization. hdl:10665/325771. WHO/MVP/EMP/IAU/2019.06. License: CC BY-NC-SA 3.0 IGO.
- "Nitrofurantoin". International Drug Price Indicator Guide. Archived from the original on 5 March 2017. Retrieved 31 August 2015.
- "NADAC as of 2018-09-12". Centers for Medicare and Medicaid Services. Retrieved 26 June 2018.
- "The Top 300 of 2019". clincalc.com. Retrieved 22 December 2018.
- "Macrobid Drug Label" (PDF). FDA. Archived (PDF) from the original on 21 April 2014. Retrieved 21 April 2014.
- Garau J (January 2008). "Other antimicrobials of interest in the era of extended-spectrum beta-lactamases: fosfomycin, nitrofurantoin and tigecycline". Clin. Microbiol. Infect. 14 Suppl 1: 198–202. doi:10.1111/j.1469-0691.2007.01852.x. PMID 18154548. Archived from the original on 2013-01-05.
- McKinnell, JA; Stollenwerk, NS; Jung, CW; Miller, LG (Jun 2011). "Nitrofurantoin compares favorably to recommended agents as empirical treatment of uncomplicated urinary tract infections in a decision and cost analysis". Mayo Clinic Proceedings. 86 (6): 480–8. doi:10.4065/mcp.2010.0800. PMC 3104907. PMID 21576512.
- Gupta, K.; Hooton, T. M.; Naber, K. G.; Wullt, B.; Colgan, R.; Miller, L. G.; Moran, G. J.; Nicolle, L. E.; Raz, R.; Schaeffer, A. J.; Soper, D. E. (2011). "International Clinical Practice Guidelines for the Treatment of Acute Uncomplicated Cystitis and Pyelonephritis in Women: A 2010 Update by the Infectious Diseases Society of America and the European Society for Microbiology and Infectious Diseases". Clinical Infectious Diseases. 52 (5): e103–e120. doi:10.1093/cid/ciq257. PMID 21292654.
- Lipsky, Benjamin A.; Byren, Ivor; Hoey, Christopher T. (2010). "Treatment of Bacterial Prostatitis". Clinical Infectious Diseases. 50 (12): 1641–1652. doi:10.1086/652861. PMID 20459324.
- Solomkin JS, Mazuski JE, Bradley JS, Rodvold KA, Goldstein EJ, Baron EJ, O'Neill PJ, Chow AW, Dellinger EP, Eachempati SR, Gorbach S, Hilfiker M, May AK, Nathens AB, Sawyer RG, Bartlett JG (January 2010). "Diagnosis and Management of Complicated Intra‐abdominal Infection in Adults and Children: Guidelines by the Surgical Infection Society and the Infectious Diseases Society of America". Clinical Infectious Diseases. 50 (2): 133–164. doi:10.1086/649554. PMID 20034345.
- Gupta, K; Scholes, D; Stamm, WE (Feb 24, 1999). "Increasing prevalence of antimicrobial resistance among uropathogens causing acute uncomplicated cystitis in women". JAMA: The Journal of the American Medical Association. 281 (8): 736–8. doi:10.1001/jama.281.8.736. PMID 10052444.
- "Nitrofurantoin Use During Pregnancy". Drugs.com. Retrieved 10 September 2019.
- Lee M, Bozzo P, Einarson A, Koren G (June 2008). "Urinary tract infections in pregnancy". Can Fam Physician. 54 (6): 853–4. PMC 2426978. PMID 18556490.
- Nordeng, H; Lupattelli, A; Romøren, M; Koren, G (Feb 2013). "Neonatal outcomes after gestational exposure to nitrofurantoin". Obstetrics and Gynecology. 121 (2 Pt 1): 306–13. doi:10.1097/AOG.0b013e31827c5f88. PMID 23344280.
- "Sulfonamides, Nitrofurantoin, and Risk of Birth Defects - ACOG". www.acog.org. Retrieved 25 November 2019.
- Goldberg, O; Moretti, M; Levy, A; Koren, G (February 2015). "Exposure to nitrofurantoin during early pregnancy and congenital malformations: a systematic review and meta-analysis". Journal of Obstetrics and Gynaecology Canada. 37 (2): 150–156. doi:10.1016/S1701-2163(15)30337-6. PMID 25767948.
- Jick, S S; Jick, H; Walker, A M; Hunter, J R (1989-09-01). "Hospitalizations for pulmonary reactions following nitrofurantoin use". Chest. 96 (3): 512–515. doi:10.1378/chest.96.3.512. ISSN 0012-3692. PMID 2766810.
- Huttner, Angela; Verhaegh, Els M.; Harbarth, Stephan; Muller, Anouk E.; Theuretzbacher, Ursula; Mouton, Johan W. (2015-09-01). "Nitrofurantoin revisited: a systematic review and meta-analysis of controlled trials". Journal of Antimicrobial Chemotherapy. 70 (9): 2456–2464. doi:10.1093/jac/dkv147. ISSN 0305-7453. PMID 26066581.
- Williams, EM; Triller, DM (May 2006). "Recurrent acute nitrofurantoin-induced pulmonary toxicity". Pharmacotherapy. 26 (5): 713–8. doi:10.1592/phco.26.5.713. PMID 16718946.
- Goemaere NN, Grijm K, van Hal PT, den Bakker MA (2008). "Nitrofurantoin-induced pulmonary fibrosis: a case report". Journal of Medical Case Reports. 2 (1): 169. doi:10.1186/1752-1947-2-169. PMC 2408600. PMID 18495029.
- Amit, G; Cohen, P; Ackerman, Z (Mar 2002). "Nitrofurantoin-induced chronic active hepatitis". The Israel Medical Association Journal : IMAJ. 4 (3): 184–6. PMID 11908259.
- Tan, IL; Polydefkis, MJ; Ebenezer, GJ; Hauer, P; McArthur, JC (February 2012). "Peripheral nerve toxic effects of nitrofurantoin". Archives of Neurology. 69 (2): 265–8. doi:10.1001/archneurol.2011.1120. PMID 22332195.
- Oplinger, M; Andrews, CO (Jan 2013). "Nitrofurantoin contraindication in patients with a creatinine clearance below 60 mL/min: looking for the evidence". The Annals of Pharmacotherapy. 47 (1): 106–11. doi:10.1345/aph.1R352. PMID 23341159.
- American Geriatrics Society 2012 Beers Criteria Update Expert Panel (Apr 2012). "American Geriatrics Society updated Beers Criteria for potentially inappropriate medication use in older adults". Journal of the American Geriatrics Society. 60 (4): 616–31. doi:10.1111/j.1532-5415.2012.03923.x. PMC 3571677. PMID 22376048.
- Antibiot. Chemother. 1978, 25, 233–252
- Shah (1989). "Reappraisal of the risk/benefit of nitrofurantoin: review of toxicity and efficacy". Adverse Drug Reactions and Acute Poisoning Reviews. 8 (4): 183–201. PMID 2694823.
- McCalla DR, Kaiser C, Green MH (1978). "Genetics of nitrofurazone resistance in Escherichia coli". J Bacteriol. 133 (1): 10–16. doi:10.1128/JB.133.1.10-16.1978. PMC 221970. PMID 338576.
- Bains A, Buna D, Hoag NA (2009). "A retrospective review assessing the efficacy and safety of nitrofurantoin in renal impairment". Canadian Pharmacists Journal. 142 (5): 248–252. doi:10.3821/1913-701X-142.5.248.
- "Drugs for bacterial infections". Treatment Guidelines from the Medical Letter. 11 (131): 65–74. July 2013. PMID 23797768.
- "Nitrofurantoin Capsules - FDA prescribing information, side effects and uses". Drugs.com. Retrieved 28 November 2017.
- Blass, Benjamin (2015-04-24). Basic Principles of Drug Discovery and Development. p. 513. ISBN 9780124115255.
- Tu Y, McCalla DR (1975). "Effect of activated nitrofurans on DNA". Biochim Biophys Acta. 402 (2): 142–49. doi:10.1016/0005-2787(75)90032-5. PMID 1100114.
- FAO: Nitrofuran study Archived 2008-12-04 at the Wayback Machine
- Pharma chief defends 400% drug price rise as a ‘moral requirement’, David Crow, Financial Times, Sept. 11, 2018
- Hiltzik, Michael. "Drug executive: It's a 'moral requirement' to charge patients the highest price". latimes.com. Retrieved 14 September 2018.
- drugs.com Archived 2015-05-18 at the Wayback Machine, Nitrofurantoin listings, page accessed May 2, 2015