Nitrofurantoin

Absorption

Nitrofurantoin reaches a Cmax of 0.875-0.963mg/L with an AUC of 2.21-2.42mg*h/L. It is 38.8-44.3% bioavailable. Taking nitrofurantoin with food increases the absorption and duration of therapeutic concentrations in the urine.

Toxicity

Symptoms of overdose include vomiting. In case of overdose, induce vomiting if it has not already occurred and increase fluid intake to promote urination. In extreme cases, nitrofurantoin can be removed from circulation by dialysis.

Description

Nitrofurantoin is an antibacterial medication used primarily to treat urinary tract and bladder infections. It has been sold under more than two dozen trade names, including Macrobid; but it is now almost always supplied as a generic.
The first US patent on the synthesis of nitrofurantoin was awarded in 1952 to Kenyon J. Hayes at the long-defunct Eaton Laboratories1 (Norwich, NY). The drug was introduced in 1953. In his 2015 book Basic Principles of Drug Discovery and Development, Benjamin E. Blass called nitrofurantoin “a surprisingly successful drug” because of its market longevity.
In 2018, a controversy erupted over the cost of the liquid formulation of nitrofurantoin. The only two US companies that produce the formulation, Nostrum Laboratories (Kansas City, MO) and Casper Pharma (East Brunswick, NJ), dramatically increased their prices: Nostrum, from the already expensive US$475 per bottle, to $2,393 and Casper to $2,800. Needless to say, an uproar ensued, heightening demands for pharma industry price reforms, an issue of much concern in the US Congress and elsewhere.
1. You can purchase vintage postcards of the Eaton buildings on Amazon and other online sellers.

Chemical properties

lemon yellow crystalline powder

Originator

Furadantin,Norwich Eaton ,US,1953

The Uses of Nitrofurantoin

A nitrofuran antibiotic with low resistance potential that is rapidly metabolized by mammals. Active against both Gram-positive and Gram-negative bacteria. Nitrofurantoin is also a prooxidant that is cytotoxic due to the generation of intracellular H2O2. Antibacterial.

The Uses of Nitrofurantoin

counterirritant

The Uses of Nitrofurantoin

A nitrofuran antibiotic with low resistance potential that is rapidly metabolized by mammals. Active against both Gram-positive and Gram-negative bacteria. Nitrofurantoin is also a prooxidant that is cytotoxic due to the generation of intracellular H2O2. Antibacterial.Environmental contaminants; Food contaminants; Heat processing contaminants

Indications

Nitrofurantoin is indicated to treat acute uncomplicated urinary tract infections.

Background

Nitrofurantoin is a nitrofuran antibiotic used to treat uncomplicated urinary tract infections. Nitrofurantoin is converted by bacterial nitroreductases to electrophilic intermediates which inhibit the citric acid cycle as well as synthesis of DNA, RNA, and protein. This drug is more resistant to the development of bacterial resistance because it acts on many targets at once. Nitrofurantoin is a second line treatment to trimethoprim/sulfamethoxazole.
Nitrofurantoin was granted FDA approval on 6 February 1953.

What are the applications of Application

Nitrofurantoin is a nitrofuran antibiotic

Definition

ChEBI: An imidazolidine-2,4-dione that is hydantoin substituted at position 1 by a [(5-nitro-2-furyl)methylene]amino group. An antibiotic that damages bacterial DNA.

Indications

Like nitrofurazone, nitrofurantoin is an effective drug that acts on a number of Grampositive and Gram-negative microorganisms (staphylococci, streptococci, dysentery bacillus, colon bacillus, paratyphoid bacillus, and others). It is primarily used for treating infectious diseases of the urinary tract (pyelitis, pyelonephritis, cystitis, urethritis). Synonyms of this drug are furadonin, ituran, phenurin, urolong, cistofuran, nitrofurin, and many others.

Manufacturing Process

To a solution of 18.9 grams (0.166 mol) n-heptaldehyde in 25 ml of isopropanol is added, with stirring, a solution of 19.1 grams (0.166 mol) of 1aminohydantoin in 110 ml water acidified with concentrated HCl. The heavy white precipitate formed is filtered and washed, until acid free, with small amounts of water and ether. The yield of N-(n-heptylidene)-1-aminohydantoin is 14 grams of MP 150°C (with decomposition). This may be recrystallized from dimethylformamide.
A mixture of 2.5 grams (0.016 mol) of 5-nitro-2-furaldoxime, 3.9 grams (0.018 mol) of N-(n-heptylidene)-1-aminohydantoin and 5 cc of sulfuric acid (density 1.84) is placed in a 250 cc beaker. It is heated with stirring at steam bath temperature for about 1.5 hours. Upon cooling, a solid precipitates which is collected by filtration, washed with water, isopropanol and ether in turn and dried at 110°C for 4 hours. There is obtained N-(5-nitro-2-furfurylidene)-1aminohydantoin in 96 to 98% yield, according to US Patent 2,927,110.

brand name

Ivadantin (Procter & Gamble);Furan;Nitrofan.

Therapeutic Function

Antibacterial (urinary)

Antimicrobial activity

It is active against almost all the common urinary pathogens, except Proteus mirabilis. It is bactericidal.
It antagonizes the activity of nalidixic acid and other quinolones in vitro, but this combination is unlikely to be used clinically.

Acquired resistance

Surprisingly for an agent that has been used for so long, resistance remains uncommon. R-factor-mediated resistance has been reported, but this appears to be very unusual. The mechanism of resistance seems to be a decreased nitroreductase activity in the target organism.
There is cross-resistance within the nitrofuran group, but none with antibiotics of other chemical classes.

General Description

Odorless lemon yellow crystals or fine yellow powder. Bitter taste.

Air & Water Reactions

Insoluble in water.

Reactivity Profile

Nitrofurantoin is sensitive to light. Nitrofurantoin is incompatible with alkalis. Nitrofurantoin is also incompatible with strong oxidizers and strong acids. Nitrofurantoin decomposes on contact with metals other than stainless steel and aluminum.

Hazard

Questionable carcinogen.

Fire Hazard

Flash point data for Nitrofurantoin are not available; however, Nitrofurantoin is probably combustible.

Pharmaceutical Applications

A synthetic compound available only for oral administration. There are three formulations, differing in their crystalline nature: microcrystalline, macrocrystalline, and a delayedrelease preparation containing a combination of the two. The macrocrystalline form is said to be less liable to give rise to the most common adverse event, nausea. However, pharmacokinetic and clinical trial evidence for this assertion is not very strong.
It is slightly soluble in water (c. 200 mg/L) but more so in dilute alkali. Solubility in ethanol is modest (500 mg/L), but the compound dissolves very well in dimethylformamide (80 g/L). If packaged in light-resistant containers and kept at room temperature, it is stable for more than 5 years. The yellow solution should be kept in the dark.

Biochem/physiol Actions

Nitrofurantoin is an antibactericidal compound that has been historically prepared by the reaction of 1-aminohydantoin sulfate and 5-nitro-2-furaldehyde diacetate. It shows activity against many Gram-positive and Gram-negative bacteria. Nitrofurantoin is effective against enterococci, staphylococci, streptococci, corneybacteria, many strains of Escherichia coli. Most strains of Proteus spp. and Pseudomonas aeurginosa are more resistant to this compound. Nitrofurantoin is activated by bacterial flavoproteins (nitrofuran reductase) to actively reduce reactive intermediates that modulate and damage ribosomal proteins or other macromolecules, such as DNA. This inhibits DNA, RNA, protein, and cell wall synthesis which causes cell death. Nitrofurantoin has a low resistance potential that is rapidly metabolized by mammals and is active against both Gram-positive and Gram-negative bacteria. It is also a pro-oxidant that is cytotoxic due to the generation of intracellular H 2O2. It is an inhibitor of glutathione reductase. Nitrofurantoin produces hepatotoxicity caused by the redox cycling of the nitro group and its radical anion which leads to oxidative stress.

Pharmacokinetics

Nitrofurantoin interferes with vital processes in bacteria, which leads to their death. Nitrofurantoin rapidly reaches therapeutic concentrations in the urine and is also cleared rapidly.

Pharmacokinetics

Oral absorption:>95%
C_max 100 mg oral: <2 mg/L after 1–4 h
Plasma half-life:0.5–1 h
Volume of distribution: 0.6 L/kg
Plasma protein binding: 60–70%
Absorption
It is absorbed mainly from the proximal small intestine and the plasma peak concentration may not be achieved for as long as 4 h. The recommendation to take the drug with food may be motivated by reducing the incidence of nausea rather than increasing bioavailability.
Bioavailability varies widely between different brands and this may not be apparent from results of standard in-vitro pharmaceutical tests. Therefore, different brands should not be substituted unless therapeutic equivalence has been formally established.
Distribution
Serum levels are low, owing to extensive metabolism and the short plasma half-life. Tissue concentrations are too low for adequate treatment of systemic infection, including pyelonephritis. Negligible concentrations are found in breast milk and only a small amount crosses the placenta.
Metabolism and excretion
About 20% of the dose is excreted in microbiologically active form in the urine, sufficient to give inhibitory concentrations against urinary pathogens for up to 6 h. With reduced renal function (creatinine clearance <60 mL/min), urinary excretion falls, and virtually ceases when creatinine clearance is below 20 mL/min. This gives rise to the risk of accumulation in the blood and inadequate urine levels. With this proviso, it can be given to elderly patients. Infants over the age of 3 months may also be treated, but in the absence of a suitable suspension, and at the recommended dosage, a 6-month baby would need to be given one-tenth of a standard 50 mg tablet.

Clinical Use

Acute dysuria and frequency
Bacteriuria in pregnancy
Prophylaxis of recurrent cystitis (reduced dosage)

Side Effects

Nausea, which may be combined with anorexia or vomiting, or both, occurs in about 30% of patients taking the microcrystalline form, causing about 10% to stop treatment. The frequency of nausea is approximately halved with the macrocrystalline formulation. Nausea is due to a direct effect on the vomiting center; it occurs early in the course, and its incidence may be reduced by taking the medication with food or milk.
Pulmonary, hepatic, neurological and hematological side effects have been reported, but are very uncommon. There are two kinds of pulmonary reaction. Acute reactions are the more common, starting within 5–10 days of the first dose, or within a few hours on re-challenge. Symptoms may resemble those found in asthma, tracheobronchitis or pneumonia, and usually resolve permanently within 2 days. There may be an eosinophilia. Subacute or chronic reactions, often referred to as pneumonitis, are of more gradual onset, and resolve only slowly when the drug is stopped. Prolonged dyspnea and cough may be accompanied by fibrosis.
Hepatic reactions follow prolonged drug usage and usually manifest as chronic active hepatitis, sometimes with cirrhosis. The prognosis is good, but recovery may take months. Peripheral neuropathy has been reported mainly in patients with pre-existing impaired renal function. The prognosis depends upon the severity of the symptoms. Unlike hepatic and pulmonary effects, for which immunological phenomena seem to be responsible, neurological events have been attributed to a direct toxic effect of the drug, one of its metabolites or the superoxide generated in vivo.
In common with other nitrofurans, nitrofurantoin may cause hemolysis in patients who lack glucose-6-phosphate dehydrogenase.

Safety Profile

Poison by ingestion and intraperitoneal routes. Human systemic effects: peripheral motor nerve recording changes, ataxia, changes in urine composition, and hemolysis with or without anemia. Human reproductive effects by ingestion: spermatogenesis. An experimental teratogen. Other experimental reproductive effects. Questionable carcinogen with experimental neoplastigenic data. Human mutation data reported. When heated to decomposition it emits toxic fumes of NOx.

Synthesis

Nitrofurantoin, 1-(5-nitrofurfurylidenamino)hydantoin (33.3.5), is synthesized from hydrazinoacetic acid (33.3.2), which is synthesized by reacting chloroacetic acid with hydrazine. Reacting hydrazinoacetic acid with potassium cyanate gives the semicarbazidoacetic acid (33.3.3), which upon heating cyclizes into 1-aminoidantoin (33.3.4). Reacting this with diacetylacetal of 5-nitrofurfurol gives the desired nitrofurantoin.

Veterinary Drugs and Treatments

Considered a urinary tract antiseptic, nitrofurantoin is used primarily in small animals, but also occasionally in horses in the treatment of lower urinary tract infections caused by susceptible bacteria. It is not effective in treating renal cortical or perinephric abscesses or other systemic infections.

Metabolism

0.8-1.8% of a dose is metabolized to aminofurantoin, and ≤0.9% of a dose is metabolized to other metabolites.

Metabolism

Nitrofurantoin is metabolised in the liver and most body tissues, while about 30-40% of a dose is excreted rapidly in the urine as unchanged nitrofurantoin. Some tubular reabsorption may occur in acid urine.