Norfloxacin
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Norfloxacin, sold under the brand name Noroxin among others, is an
antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of ...
that belongs to the class of
fluoroquinolone antibiotics A quinolone antibiotic is a member of a large group of broad-spectrum bacteriocidals that share a bicyclic core structure related to the substance 4-quinolone. They are used in human and veterinary medicine to treat bacterial infections, as wel ...
. It is used to treat
urinary tract infections A urinary tract infection (UTI) is an infection that affects part of the urinary tract. When it affects the lower urinary tract it is known as a bladder infection (cystitis) and when it affects the upper urinary tract it is known as a kidney ...
, gynecological infections, inflammation of the prostate gland,
gonorrhea Gonorrhea, colloquially known as the clap, is a sexually transmitted infection (STI) caused by the bacterium '' Neisseria gonorrhoeae''. Infection may involve the genitals, mouth, or rectum. Infected men may experience pain or burning with ...
and bladder infection. Eye drops were approved for use in children older than one year of age. Norfloxacin is associated with a number of rare serious adverse reactions as well as spontaneous tendon ruptures and irreversible
peripheral neuropathy Peripheral neuropathy, often shortened to neuropathy, is a general term describing disease affecting the peripheral nerves, meaning nerves beyond the brain and spinal cord. Damage to peripheral nerves may impair sensation, movement, gland, or or ...
. Tendon problems may manifest long after therapy had been completed and in severe cases may result in lifelong disabilities. It was patented in 1977 and approved for medical use in 1983.


Medical uses

The initial approval by the
U.S. Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...
(FDA) in 1986 encompassed the following indications: *Uncomplicated urinary tract infections (including cystitis) *Complicated urinary tract infections (restricted use) *Uncomplicated urethral and cervical gonorrhea (''however this indication is no longer considered to be effective by some experts due to bacterial resistance'') *Prostatitis due to ''Escherichia coli''. *Syphilis treatment: Norfloxacin has not been shown to be effective in the treatment of syphilis. Antimicrobial agents used in high doses for short periods of time to treat gonorrhea may mask or delay the symptoms of incubating syphilis.http://www.accessdata.fda.gov/drugsatfda_docs/appletter/2004/19384s040,042,043ltr.pdf Although fluoroquinolones are sometimes used to treat
typhoid Typhoid fever, also known as typhoid, is a disease caused by '' Salmonella'' serotype Typhi bacteria. Symptoms vary from mild to severe, and usually begin six to 30 days after exposure. Often there is a gradual onset of a high fever over several ...
and
paratyphoid fever Paratyphoid fever, also known simply as paratyphoid, is a bacterial infection caused by one of the three types of ''Salmonella enterica''. Symptoms usually begin 6–30 days after exposure and are the same as those of typhoid fever. Often, a grad ...
, norfloxacin had more clinical failures than the other fluoroquinolones (417 participants, 5 trials). In ophthalmology, Norfloxacin licensed use is limited to the treatment of conjunctival infections caused by susceptible bacteria. Norfloxacin has been restricted in the
Republic of Ireland Ireland ( ga, Éire ), also known as the Republic of Ireland (), is a country in north-western Europe consisting of 26 of the 32 counties of the island of Ireland. The capital and largest city is Dublin, on the eastern side of the island. A ...
due to the risks of '' C. difficile'' super infections and permanent nerve as well as tendon injuries. It licensed use in acute and chronic complicated kidney infections has been withdrawn as a result. The
European Medicines Agency The European Medicines Agency (EMA) is an agency of the European Union (EU) in charge of the evaluation and supervision of medicinal products. Prior to 2004, it was known as the European Agency for the Evaluation of Medicinal Products or Euro ...
, also in 2008, had recommended restricting the use of oral norfloxacin to treat urinary infections. CHMP had concluded that the marketing authorizations for norfloxacin, when used in the treatment of acute or chronic complicated pyelonephritis, should be withdrawn because the benefits do not outweigh their risks in this indication. CHMP stated that doctors should not prescribe oral norfloxacin for complicated pyelonephritis and should consider switching patients already taking oral norfloxacin for this type of infection to an alternative antibiotic. Norfloxacin is used for prevention of
spontaneous bacterial peritonitis Spontaneous bacterial peritonitis (SBP) is the development of a bacterial infection in the peritoneum, despite the absence of an obvious source for the infection. It is specifically an infection of the ascitic fluid – an increased volume of pe ...
in cirrhotic patients who have a low ascites fluid protein level, impaired renal function, severe liver disease, have had a prior episode of spontaneous bacterial peritonitis, or esophageal variceal bleeding. Note: Norfloxacin may be licensed for other uses, or restricted, by the various regulatory agencies worldwide.


Contraindications

As noted above, under licensed use, norfloxacin is also now considered to be contraindicated for the treatment of certain sexually transmitted diseases by some experts due to bacterial resistance. Norfloxacin is contraindicated in those with a history of tendonitis, tendon rupture and those with a hypersensitivity to fluoroquinolones. There are three contraindications found within the 2008 package insert: *"Noroxin (norfloxacin) is contraindicated in persons with a history of hypersensitivity, tendinitis, or tendon rupture associated with the use of norfloxacin or any member of the quinolone group of antimicrobial agents." *"Quinolones, including norfloxacin, have been shown in vitro to inhibit CYP1A2. Concomitant use with drugs metabolized by CYP1A2 (e.g., caffeine, clozapine, ropinirole, tacrine, theophylline, tizanidine) may result in increased substrate drug concentrations when given in usual doses. Patients taking any of these drugs concomitantly with norfloxacin should be carefully monitored." *"Concomitant administration with
tizanidine Tizanidine, sold under the brand name Zanaflex among others, is a medication that is used to treat muscle spasticity due to spinal cord injury or multiple sclerosis as well as spastic cerebral palsy. Effectiveness appears similar to baclofen o ...
is contraindicated" Norfloxacin is also considered to be contraindicated within the pediatric population. *Pregnancy Norfloxacin has been reported to rapidly cross the blood-placenta and blood-milk barrier, and is extensively distributed into the fetal tissues. For this reason norfloxacin and other fluoroquinolones are contraindicated during pregnancy due to the risk of spontaneous abortions and birth defects. The fluoroquinolones have also been reported as being present in the mother's milk and are passed on to the nursing child, which may increases the risk of the child having an adverse reaction even though the child had never been prescribed or taken any of the drugs found within this class. As safer alternatives are generally available norfloxacin is contraindicated during pregnancy, especially during the first trimester. The manufacturer only recommends use of norfloxacin during pregnancy when benefit outweighs risk. *Children A 1998 retrospective survey found that numerous side effects have been recorded in reference to the unapproved use of norfloxacin in the pediatric population. Fluoroquinolones are not licensed by the FDA for use in children due to the risk of fatalities as well as permanent injury to the musculoskeletal system, with two exceptions.
Ciprofloxacin Ciprofloxacin is a fluoroquinolone antibiotic used to treat a number of bacterial infections. This includes bone and joint infections, intra abdominal infections, certain types of infectious diarrhea, respiratory tract infections, skin infec ...
is being licensed for the treatment of Complicated Urinary Tract Infections and Pyelonephritis due to Escherichia coli and Inhalational Anthrax (post-exposure) and
levofloxacin Levofloxacin, sold under the brand name Levaquin among others, is an antibiotic medication. It is used to treat a number of bacterial infections including acute bacterial sinusitis, pneumonia, H. pylori (in combination with other medications), ...
was recently licensed for the treatment of Inhalational Anthrax (post-exposure). However, the Fluoroquinolones are licensed to treat lower respiratory infections in children with
cystic fibrosis Cystic fibrosis (CF) is a rare genetic disorder that affects mostly the lungs, but also the pancreas, liver, kidneys, and intestine. Long-term issues include difficulty breathing and coughing up mucus as a result of frequent lung infections. O ...
in the UK.


Adverse effects

In general, fluoroquinolones are well tolerated, with most side-effects being mild to moderate. On occasion, serious
adverse effect An adverse effect is an undesired harmful effect resulting from a medication or other intervention, such as surgery. An adverse effect may be termed a "side effect", when judged to be secondary to a main or therapeutic effect. The term complica ...
s occur. Common side-effects include gastrointestinal effects such as nausea, vomiting, and diarrhea, as well as headache and insomnia. The overall rate of adverse events in patients treated with fluoroquinolones is roughly similar to that seen in patients treated with other antibiotic classes. A U.S. Centers for Disease Control study found patients treated with fluoroquinolones experienced adverse events severe enough to lead to an emergency department visit more frequently than those treated with cephalosporins or macrolides, but less frequently than those treated with penicillins, clindamycin, sulfonamides, or vancomycin. Post-marketing surveillance has revealed a variety of relatively rare but serious adverse effects that are associated with all members of the fluoroquinolone antibacterial class. Among these, tendon problems and exacerbation of the symptoms of the neurological disorder
myasthenia gravis Myasthenia gravis (MG) is a long-term neuromuscular junction disease that leads to varying degrees of skeletal muscle weakness. The most commonly affected muscles are those of the eyes, face, and swallowing. It can result in double vision, dro ...
are the subject of "black box" warnings in the United States. The most severe form of tendonopathy associated with fluoroquinolone administration is tendon rupture, which in the great majority of cases involves the Achilles tendon. Younger people typically experience good recovery, but permanent disability is possible, and is more likely in older patients. The overall frequency of fluoroquinolone-associated Achilles tendon rupture in patients treated with ciprofloxacin or levofloxacin has been estimated at 17 per 100,000 treatments. Risk is substantially elevated in the elderly and in those with recent exposure to topical or systemic corticosteroid therapy. Simultaneous use of
corticosteroids Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex of vertebrates, as well as the synthetic analogues of these hormones. Two main classes of corticosteroids, glucocorticoids and mineralocorticoids, are involve ...
is present in almost one-third of quinolone-associated tendon rupture. Tendon damage may manifest during, as well as up to a year after fluoroquinolone therapy has been completed. FQs prolong the QT interval by blocking voltage-gated potassium channels. Prolongation of the QT interval can lead to torsades de pointes, a life-threatening arrhythmia, but in practice this appears relatively uncommon in part because the most widely prescribed fluoroquinolones (ciprofloxacin and levofloxacin) only minimally prolong the QT interval. ''Clostridium difficile''-associated diarrhea may occur in connection with the use of any antibacterial drug, especially those with a broad spectrum of activity such as clindamycin, cephalosporins, and fluoroquinolones. Fluoroquinoline treatment is associated with risk that is similar to or less than that associated with broad spectrum cephalosporins. Fluoroquinoline administration may be associated with the acquisition and outgrowth of a particularly virulent ''Clostridium'' strain. The U.S. prescribing information contains a warning regarding uncommon cases of peripheral neuropathy, which can be permanent. Other nervous system effects include insomnia, restlessness, and rarely, seizure, convulsions, and psychosis Other rare and serious adverse events have been observed with varying degrees of evidence for causation. Events that may occur in acute overdose are rare, and include
kidney failure Kidney failure, also known as end-stage kidney disease, is a medical condition in which the kidneys can no longer adequately filter waste products from the blood, functioning at less than 15% of normal levels. Kidney failure is classified as eit ...
and
seizure An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with los ...
. Susceptible groups of patients, such as children and the elderly, are at greater risk of adverse reactions during therapeutic use.


Interactions

The toxicity of drugs that are metabolised by the
cytochrome P450 Cytochromes P450 (CYPs) are a Protein superfamily, superfamily of enzymes containing heme as a cofactor (biochemistry), cofactor that functions as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are ...
system is enhanced by concomitant use of some quinolones. Quinolones, including norfloxacin, may enhance the effects of oral anticoagulants, including warfarin or its derivatives or similar agents. When these products are administered concomitantly, prothrombin time or other suitable coagulation tests should be closely monitored. Coadministration may dangerously increase coumadin
warfarin Warfarin, sold under the brand name Coumadin among others, is a medication that is used as an anticoagulant (blood thinner). It is commonly used to prevent blood clots such as deep vein thrombosis and pulmonary embolism, and to prevent strok ...
activity; INR should be monitored closely. They may also interact with the
GABA A receptor The GABAA receptor (GABAAR) is an ionotropic receptor and ligand-gated ion channel. Its endogenous ligand is γ-aminobutyric acid (GABA), the major inhibitory neurotransmitter in the central nervous system. Upon opening, the GABAA receptor on ...
and cause neurological symptoms; this effect is augmented by certain
non-steroidal anti-inflammatory drug Non-steroidal anti-inflammatory drugs (NSAID) are members of a therapeutic drug class which reduces pain, decreases inflammation, decreases fever, and prevents blood clots. Side effects depend on the specific drug, its dose and duration of ...
s. The concomitant administration of a non-steroidal anti-inflammatory drug (NSAID) with a quinolone, including norfloxacin, may increase the risk of CNS stimulation and convulsive seizures. Therefore, norfloxacin should be used with caution in individuals receiving NSAIDS concomitantly. Elevated serum levels of cyclosporine have been reported with concomitant use of cyclosporine with norfloxacin. Therefore, cyclosporine serum levels should be monitored and appropriate cyclosporine dosage adjustments made when these drugs are used concomitantly. The concomitant administration of quinolones including norfloxacin with glyburide (a sulfonylurea agent) has, on rare occasions, resulted in severe hypoglycemia. Therefore, monitoring of blood glucose is recommended when these agents are co-administered.


Medications

Some quinolones exert an inhibitory effect on the cytochrome P-450 system, thereby reducing theophylline clearance and increasing theophylline blood levels. Coadministration of certain fluoroquinolones and other drugs primarily metabolized by CYP1A2 (e.g. theophylline, methylxanthines, tizanidine) results in increased plasma concentrations and could lead to clinically significant side effects of the coadministered drug. Additionally other fluoroquinolones, especially enoxacin, and to a lesser extent ciprofloxacin and pefloxacin, also inhibit the metabolic clearance of theophylline. Such drug interactions are associated with the molecular structural modifications of the quinolone ring, specifically interactions involving NSAIDS and
theophylline Theophylline, also known as 1,3-dimethylxanthine, is a phosphodiesterase inhibiting drug used in therapy for respiratory diseases such as chronic obstructive pulmonary disease (COPD) and asthma under a variety of brand names. As a member of the ...
. As such, these drug interactions involving the fluoroquinolones appear to be drug specific rather than a class effect. The fluoroquinolones have also been shown to interfere with the metabolism of caffeine and the absorption of levothyroxine. The interference with the metabolism of caffeine may lead to the reduced clearance of caffeine and a prolongation of its serum half-life, resulting in a caffeine overdose. This may lead to reduced clearance of caffeine and a prolongation of the plasma's half-life that may lead to accumulation of caffeine in plasma when products containing caffeine are consumed while taking norfloxacin. The use of NSAIDs (Non Steroid Anti Inflammatory Drugs) while undergoing fluoroquinolone therapy is contra-indicated due to the risk of severe CNS adverse reactions, including but not limited to seizure disorders. Fluoroquinolones with an unsubstituted piperazinyl moiety at position 7 have the potential to interact with NSAIDs and/or their metabolites, resulting in antagonism of GABA neurotransmission. The use of norfloxacin concomitantly has also been associated with transient elevations in serum creatinine in patients receiving cyclosporine, on rare occasions, resulted in severe hypoglycemia with sulfonylurea. Renal tubular transport of methotrexate may be inhibited by concomitant administration of norfloxacin, potentially leading to increased plasma levels of methotrexate. This might increase the risk of methotrexate toxic reactions. Current or past treatment with oral corticosteroids is associated with an increased risk of Achilles tendon rupture, especially in elderly patients who are also taking the fluoroquinolones.


Overdose

Treatment of overdose includes emptying of the stomach via induced vomiting or by
gastric lavage Gastric lavage, also commonly called stomach pumping or gastric irrigation, is the process of cleaning out the contents of the stomach. Since its first recorded use in early 19th century, it has become one of the most routine means of eliminating ...
. Careful monitoring and supportive treatment, monitoring of renal and liver function, and maintaining adequate hydration is recommended by the manufacturer. Administration of magnesium, aluminum, or calcium containing antacids can reduce the absorption of norfloxacin.


Mechanism of action

Norfloxacin is a
broad-spectrum antibiotic A broad-spectrum antibiotic is an antibiotic that acts on the two major bacterial groups, Gram-positive and Gram-negative, or any antibiotic that acts against a wide range of disease-causing bacteria. These medications are used when a bacterial inf ...
that is active against both
Gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bacte ...
and
Gram-negative Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall ...
bacteria. It functions by inhibiting
DNA gyrase DNA gyrase, or simply gyrase, is an enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrat ...
, a type II
topoisomerase DNA topoisomerases (or topoisomerases) are enzymes that catalyze changes in the topological state of DNA, interconverting relaxed and supercoiled forms, linked (catenated) and unlinked species, and knotted and unknotted DNA. Topological issues i ...
, and topoisomerase IV, enzymes necessary to separate bacterial DNA, thereby inhibiting cell division. Norfloxacin does not bind to DNA gyrase but does bind to the substrate DNA. A review in 2001 suggests that
cytotoxicity Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are an immune cell or some types of venom, e.g. from the puff adder (''Bitis arietans'') or brown recluse spider (''Loxosceles reclusa''). Cell physiology Treating cells ...
of fluoroquinolones is likely a 2-step process involving (1) conversion of the topoisomerase-quinolone-DNA complex to an irreversible form and (2) generation of a double-strand break by denaturation of the topoisomerase.


Pharmacokinetics

"Absorption of norfloxacin is rapid following single doses of 200 mg, 400 mg and 800 mg. At the respective doses, mean peak serum and plasma concentrations of 0.8, 1.5 and 2.4 μg/mL are attained approximately one hour after dosing. The effective half-life of norfloxacin in serum and plasma is 3–4 hours. Steady-state concentrations of norfloxacin will be attained within two days of dosing. Renal excretion occurs by both glomerular filtration and tubular secretion as evidenced by the high rate of renal clearance (approximately 275 mL/min). Within 24 hours of drug administration, 26 to 32% of the administered dose is recovered in the urine as norfloxacin with an additional 5-8% being recovered in the urine as six active metabolites of lesser antimicrobial potency. Only a small percentage (less than 1%) of the dose is recovered thereafter. Fecal recovery accounts for another 30% of the administered dose. Two to three hours after a single 400-mg dose, urinary concentrations of 200 μg/mL or more are attained in the urine. In healthy volunteers, mean urinary concentrations of norfloxacin remain above 30 μg/mL for at least 12 hours following a 400-mg dose. The urinary pH may affect the solubility of norfloxacin. Norfloxacin is least soluble at urinary pH of 7.5 with greater solubility occurring at pHs above and below this value. The serum protein binding of norfloxacin is between 10 and 15%." Quoting from the 2009 package insert for Noroxin. Biotransformation is via the liver and kidneys, with a half-life of 3–4 hours.


History

The first members of the quinolone antibacterial class were relatively low potency drugs such as
nalidixic acid Nalidixic acid (tradenames Nevigramon, NegGram, Wintomylon and WIN 18,320) is the first of the synthetic quinolone antibiotics. In a technical sense, it is a naphthyridone, not a quinolone: its ring structure is a 1,8-naphthyridine nucleus that ...
, used mainly in the treatment of urinary tract infections owing to their renal excretion and propensity to be concentrated in urine. In 1979 the publication of a patent filed by the pharmaceutical arm of Kyorin Seiyaku Kabushiki Kaisha disclosed the discovery of norfloxacin, and the demonstration that certain structural modifications including the attachment of a fluorine atom to the quinolone ring leads to dramatically enhanced antibacterial potency. In spite of the substantial increase in antibacterial activity of norfloxacin relative to early fluoroquinolones, it did not become a widely used antibiotic. Other companies initiated fluoroquinolone discovery programs in the aftermath of the publication of the norfloxacin patent. Bayer Pharmaceuticals discovered that the addition of a single carbon atom to the norfloxacin structure provided another 4 to 10-fold improvement in activity.
Ciprofloxacin Ciprofloxacin is a fluoroquinolone antibiotic used to treat a number of bacterial infections. This includes bone and joint infections, intra abdominal infections, certain types of infectious diarrhea, respiratory tract infections, skin infec ...
reached the market just one year after norfloxacin and achieved sales of 1.5 billion Euros at its peak. Kyorin granted Merck & Company, Inc., an exclusive license (in certain countries, including the United States), to import and distribute Norfloxacin under the brand name Noroxin. The
U.S. Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...
(FDA) approved Noroxin for distribution in the United States on October 31, 1986.


Availability

In most countries, all formulations require a prescription. In Colombia (South America) it is marketed under Ambigram from Laboratorios Bussié Noroxin was discontinued in the US as of April 2014 See the latest package insert for norfloxacin (Noroxin) for additional details.


References


External links

{{QuinoloneAntiBiotics CYP3A4 inhibitors Fluoroquinolone antibiotics 1,4-di-hydro-7-(1-piperazinyl)-4-oxo-3-quinolinecarboxylic acids AstraZeneca brands