Norfloxacin

Pronunciation

(nor FLOKS a sin)

U.S. Brand Names

Noroxin®

Generic Available

Canadian Brand Names

Apo-Norflox®; Norfloxacine®; Novo-Norfloxacin; PMS-Norfloxacin; Riva-Norfloxacin

Use

Uncomplicated urinary tract infections and cystitis caused by susceptible gram-negative and gram-positive bacteria; sexually-transmitted disease (eg, uncomplicated urethral and cervical gonorrhea) caused by N. gonorrhoeae ; prostatitis due to E. coli

Pregnancy Risk Factor

Pregnancy Implications

Reports of arthropathy (observed in immature animals and reported rarely in humans) have limited the use of fluoroquinolones in pregnancy. Teratogenic effects have not been reported with norfloxacin in animal studies; however, embryonic loss has been reported with one species. Norfloxacin crosses the placenta. The Teratogen Information System concluded that therapeutic doses during pregnancy are unlikely to produce substantial teratogenic risk, but data are insufficient to say that there is no risk. There are no adequate and well-controlled studies in pregnant women. When considering treatment for life-threatening infection and/or prolonged duration of therapy, the potential risk to the fetus must be balanced against the severity of the potential illness.

Lactation

Excretion in breast milk unknown/not recommended

Contraindications

Hypersensitivity to norfloxacin, quinolones, or any component of the formulation

Warnings/Precautions

Concurrent disease:

Renal impairment: Use caution with renal impairment.

Myasthenia gravis: Quinolones may exacerbate myasthenia gravis, use with caution (rare, potentially life-threatening weakness of respiratory muscles may occur).

G6PD deficiency: Use caution in patients with glucose-6-phosphate dehydrogenase deficiency.

Key adverse reactions:

Allergic reactions: Severe hypersensitivity reactions, including anaphylaxis, have occurred with quinolone therapy. If an allergic reaction occurs (itching, urticaria, dyspnea, facial edema, loss of consciousness, tingling, cardiovascular collapse), discontinue drug immediately.

Tendon rupture: Tendon inflammation and/or rupture have been reported with norfloxacin and other quinolone antibiotics. Risk may be increased with concurrent corticosteroids, particularly in the elderly. Discontinue at first sign of tendon inflammation or pain.

CNS effects: CNS stimulation may occur which may lead to tremor, restlessness, confusion, and very rarely to hallucinations or convulsive seizures.

QTc prolongation: Use may be associated (rarely) with prolongation of QTc interval; avoid concurrent use with class Ia and class III antiarrhythmics; use caution with other drugs which may cause QTc prolongation.

Photosensitization: Avoid excessive exposure to sunlight; other quinolones have been associated with phototoxicity.

Neuropathy/paresthesia: May be associated with the development of peripheral neuropathy and/or paresthesias; discontinue in patients who develop symptoms consistent with neuropathy.

Developmental effects: Not recommended in children <18 years of age; other quinolones have caused transient arthropathy in children; use with caution in patients with known or suspected CNS disorders.

Superinfection: Prolonged use may result in superinfection; pseudomembranous colitis may occur and should be considered in all patients who present with diarrhea.

Adverse Reactions

1% to 10%:

Central nervous system: Headache (3%), dizziness (3%)

Gastrointestinal: Nausea (4%)

Neuromuscular & skeletal: Weakness (1%)

<1%, postmarketing, and/or case reports: Abdominal pain, acute renal failure, agranulocytosis, anaphylaxis, anaphylactoid reactions, angioedema, anorexia, anxiety, arthralgia, arthritis, ataxia, back pain, bitter taste, cholestatic jaundice, confusion, constipation, CPK increased, depression, diarrhea, diplopia, dysgeusia, dyspepsia, dyspnea, erythema multiforme, erythema, exacerbation of myasthenia gravis, exfoliative dermatitis, fever, flatulence, GI bleeding, Guillain-Barré syndrome, hearing loss, heartburn, hemolytic anemia (sometimes associated with G6PD deficiency), hepatitis, hyperhidrosis, insomnia, jaundice, leukopenia, loose stools, myalgia, myoclonus, neutropenia, pancreatitis, paresthesia, peripheral neuropathy, photosensitivity, pruritus, pseudomembraneous colitis, psychotic reactions, QTc prolongation, rash, seizure, serum creatinine/BUN increased, somnolence, Stevens-Johnson syndrome, thrombocytopenia, tinnitus, torsade de pointes, toxic epidermal necrolysis, transaminases increased, tremor, urticaria, vasculitis, vomiting, weakness, ventricular arrhythmia, xerostomia

Overdosage/Toxicology

Symptoms of overdose include acute renal failure and seizures. Following GI decontamination, use supportive measures.

Drug Interactions

Inhibits CYP1A2 (strong), 3A4 (moderate)

Corticosteroids: Concurrent use may increase the risk of tendon rupture, particularly in elderly patients (overall incidence rare).

Cyclosporine: Norfloxacin may increase serum cyclosporine concentrations; monitor

CYP1A2 substrates: Norfloxacin may increase the levels/effects of CYP1A2 substrates. Example substrates include aminophylline, fluvoxamine, mexiletine, mirtazapine, ropinirole, and trifluoperazine.

CYP3A4 substrates: Norfloxacin may increase the levels/effects of CYP3A4 substrates. Example substrates include benzodiazepines, calcium channel blockers, mirtazapine, nateglinide, nefazodone, sildenafil (and other PDE-5 inhibitors), tacrolimus, and venlafaxine. Selected benzodiazepines (midazolam and triazolam), cisapride, ergot alkaloids, selected HMG-CoA reductase inhibitors (lovastatin and simvastatin), and pimozide are generally contraindicated with strong CYP3A4 inhibitors.

Glyburide: Quinolones may increase the effect of glyburide; monitor.

Metal cations (aluminum, calcium, iron, magnesium, and zinc) bind quinolones in the gastrointestinal tract and inhibit absorption. Concurrent administration of most antacids, oral electrolyte supplements, quinapril, sucralfate, and some didanosine formulations (chewable/buffered tablets and pediatric powder for oral suspension) should be avoided. Norfloxacin should be administered 4 hours before or 8 hours after these agents.

Nitrofurantoin: May antagonize the activity of norfloxacin in treating UTIs.

Probenecid: May decrease renal secretion of norfloxacin.

QTc-prolonging agents: Effects may be additive with norfloxacin. Avoid concurrent use with Class Ia and Class III antiarrhythmics; use caution with other drugs known to prolong QTc, including erythromycin, cisapride, antipsychotics, and cyclic antidepressants.

Theophylline: Norfloxacin may increase serum levels/effects of theophylline; monitor.

Warfarin: The hypoprothrombinemic effect of warfarin may be enhanced by some quinolone antibiotics; monitor INR.

Ethanol/Nutrition/Herb Interactions

Food: Norfloxacin average peak serum concentrations may be decreased if taken with dairy products.

Herb/Nutraceutical: Avoid dong quai, St John's wort (may also cause photosensitization).

Stability

Store at 25°C (77°F); keep container tightly closed

Mechanism of Action

Norfloxacin is a DNA gyrase inhibitor. DNA gyrase is an essential bacterial enzyme that maintains the superhelical structure of DNA. DNA gyrase is required for DNA replication and transcription, DNA repair, recombination, and transposition; bactericidal

Pharmacodynamics/Kinetics

Absorption: Oral: Rapid, up to 40%

Distribution: Crosses placenta; small amounts enter breast milk

Protein binding: 15%

Metabolism: Hepatic

Half-life elimination: 3-4 hours; Renal impairment (Clcr 30 mL/minute): 6.5 hours; Elderly: 4 hours

Time to peak, serum: 1-2 hours

Excretion: Urine (26% to 36%); feces (30%)

Dosage

Oral: Adults:

Urinary tract infections: 400 mg twice daily for 3-21 days depending on severity of infection or organism sensitivity; maximum: 800 mg/day

Uncomplicated gonorrhea: 800 mg as a single dose (CDC recommends as an alternative regimen to ciprofloxacin or ofloxacin)

Prostatitis: 400 mg every 12 hours for 4 weeks

Dosing interval in renal impairment: Clcr 10-30 mL/minute: Urinary tract infections: Administer 400 mg every 24 hours

Administration

Hold antacids or sucralfate for 3-4 hours after giving norfloxacin; do not administer together. Best taken on an empty stomach with water (1 hour before or 2 hours after meals, milk, or other dairy products).

Dietary Considerations

Oral formulations should be administered on an empty stomach with water (1 hour before or 2 hours after meals, milk, or other dairy products).

Patient Education

Inform prescriber of all prescriptions, OTC medications, or herbal products you are taking, and any allergies you have. Do not take any new medication during therapy unless approved by prescriber. Take as directed for as long as directed, preferably on an empty stomach, 1 hour before or 2 hours after meals. Do not alter dose or discontinue without consulting prescriber. Maintain adequate hydration (2-3 L/day of fluids) unless instructed to restrict fluid intake. You may experience dizziness, lightheadedness, or headache (use caution when driving or engaging in tasks that require alertness until response to drug is known); nausea, vomiting, anorexia, or dry mouth (small, frequent meals, frequent mouth care, sucking lozenges, or chewing gum may help); diarrhea (buttermilk, boiled milk, or yogurt may help); or photosensitivity (use sunscreen, wear protective clothing and eyewear, and avoid direct sunlight). If inflammation or tendon pain occurs discontinue use immediately and report to prescriber. If allergic reaction occurs (itching urticaria, respiratory difficulty, facial edema, difficulty swallowing, loss of consciousness, tingling, chest pain, palpitations), discontinue use immediately and report to prescriber. Contact prescriber if you experience pain in your extremities, burning, tingling, numbness, and/or weakness. Report palpitations or chest pain; persistent diarrhea or constipation; signs of infection (unusual fever or chills; vaginal itching or foul-smelling vaginal discharge; easy bruising or bleeding); excessive sleepiness; or agitation. Pregnancy/breast-feeding precautions: Inform prescriber if you are or intend to become pregnant. Do not breast-feed.

Dental Health: Effects on Dental Treatment

No significant effects or complications reported

Dental Health: Vasoconstrictor/Local Anesthetic Precautions

No information available to require special precautions

Mental Health: Effects on Mental Status

May cause dizziness, drowsiness, or insomnia; quinolones reported to cause restlessness, hallucinations, euphoria, depression, panic, and paranoia

Mental Health: Effects on Psychiatric Treatment

Inhibits CYP1A2 isoenzyme; use caution with clozapine and other psychotropics; monitor for adverse effects

Dosage Forms

Tablet: 400 mg

References

Hooper DC and Wolfson JS, "Fluoroquinolone Antimicrobial Agents," N Engl J Med , 1991, 324(6):384-94.

Lo WY and Friedman JM, "Teratogenicity of Recently Introduced Medications in Human Pregnancy," Obstet Gynecol , 2002, 100(3):465-73.

Loebstein R, Lalkin A, Addis A, et al, "Pregnancy Outcome After Gestational Exposure to Terfenadine: A Multicenter, Prospective Controlled Study," J Allergy Clin Immunol , 1999, 104(5):953-6.

Lomaestro BM and Bailie GR, "Quinolone-Cation Interactions: A Review," DICP , 1991, 25(11):1249-58.

Nilsson-Ehle I and Ljungberg B, "Quinolone Disposition in the Elderly: Practical Implications," Drugs Aging , 1991, 1(4):279-88.

Stein GE, "The 4-Quinolone Antibiotics: Past, Present, and Future," Pharmacotherapy , 1988, 8(6):301-14.

Walker RC and Wright AJ, "The Fluoroquinolones," Mayo Clin Proc , 1991, 66(12):1249-59.

International Brand Names

Ambigram® (CO, DO, GT, HN, PA, SV); Amicrobin® (ES); Apirol® (IL); Apo-Norflox® (CA); Baccidal® (ES, JP); Bacteriotal® (GT); Bactracid® (DE); Barazan® (DE); Bexinor® (SG); B.G.B Norflox® (TH); Biofloxin® (IN); Bio Tarbun® (AR); Chibroxin® (AR, BR, CR, CY, DE, EG, ES, GT, HK, HN, HR, JO, KW, LB, PA, PL, RO, SG, SV, SY); Chibroxine® (FR); Chibroxol® (BE, LU, NL); Difoxacil® (MX); Effectsal® (SG); Epinor® (RO); Esclebin® (ES); Espeden® (ES); Firin® (DE); Flossac® (IT); Floxacin® (AT, BR, DO, GT, HN, MX, SV); Floxamicin® (AR); Floxatral® (AR); Floxinol® (BR); Fluseminal® (RO); Foxin® (TH); Fulgram® (CL, IT); Gonorcin® (TH); Grenis® (RO); Gyrablock® (CY, CZ, JO, RU, SG, SK); H-Norfloxacin® (RO); Insensye® (AU); Janacin® (TH); Lexfor® (TH); Lexinor® (FI, HK, ID, SE, TH); Manoflox® (TH); Memento NF® (AR); Myfloxin® (TH); Nalion® (ES); Nefrixine® (CO); Negaflox® (RO, ZA); Noflo® (JP); Nofocin® (YU); Nolicin® (CZ, HR, HU, PL, RO, RU, SI); Nolicin-S® (HU); Noprose® (CO); Noracin® (TH); Norax® (JO, RO); Norbactin® (IN, PL, RU, SG, TH); Norcin® (TH); Norcin Utopian® (TH); Norfcin® (TH); Norfen® (ZA); Norfloaxacin Heumann® (DE); Norflocin-Mepha® (CH); Norflocin® (TH); Norflogen® (EC); Norflohexal® (DE); Norflok® (ES); Norflol® (AR); Norflophar® (BE); Norflosal® (DE); Norflox-1A Pharma® (DE); Norfloxacina Ahimsa® (AR); Norfloxacina® (BR, DO, RO); Norfloxacin AbZ® (DE); Norfloxacin-acis® (DE); Norfloxacina Craveri® (AR); Norfloxacina EG® (IT); Norfloxacina Fabra® (AR); Norfloxacina Fada® (AR); Norfloxacin AL® (DE); Norfloxacina MK® (CO); Norfloxacina Northia® (AR); Norfloxacina Richet® (AR); Norfloxacin Biochemie® (FI, SE); Norfloxacine® (CA); Norfloxacin® (GB, RO, TH); Norfloxacin Helvepharm® (CH); Norfloxacin Heumann® (DE); Norfloxacino Abello® (ES); Norfloxacino Bayvit® (ES); Norfloxacino® (BR, EC); Norfloxacino Geminis® (ES); Norfloxacino Generix® (ES); Norfloxacino Genfar® (EC); Norfloxacino MK® (CR, DO, GT, HN, PA, SV); Norfloxacino Normon® (ES); Norfloxacino Qualix® (ES); Norfloxacin-ratiopharm® (AT, BE, DE, FI); Norfloxacin Stada® (DE); Norflox-AZU® (DE); Norfloxbeta® (DE); Norflox® (IN, RO); Norfloxin® (TH); Norflox-Puren® (DE); Norflox-Sandoz® (DE); norflox von ct® (DE); Norfluxx® (DE); Norilet® (RU); Normax® (IN, RU); Noroxin® (AR, AU, CH, CL, ES, FI, IT, MX, NL, NZ, PT, TR, ZA); Noroxine® (FR); Norsa® (TH); Norsol® (AR, CH); Norxacin® (TH); Norxia-200® (TH); Novo-Norfloxacin (CA); Noxine® (TH); Noxinor® (TH); Noxoratio® (PL); Noxufen® (CH); Oranor® (MX); PMS-Norfloxacin (CA); Proxinor® (TH); Pyrflox® (ID); Quinoflex® (PT); Quinoform® (BR); Renosept® (YU); Respexil® (BR); Rexacin® (TH); Ritromine® (AR); Riva-Norfloxacin (CA); Sebercim® (IT); Sefnor® (SG); Senro® (ES); Simbra® (GT); Snoffocin® (TH); Spectrama® (RO); Trizolin® (CY); Uniao Norfloxacino® (BR); Urekolin® (CL); Uricin® (YU); Urinex® (CO); Urinox® (TH); Uritracin® (TH); Uritrat® (BR); Urobacid® (AT, CY, ID, JO, KW, LB, SG); Uroctal® (EG, ES); Uroflox® (BR, PT); Urofloxin® (DO); Uro Linfol® (AR); Uronovag® (AR); Uroplex® (BR); Uroseptal® (AR, BR); Urospes-N® (RO); Urotem® (AR); Uroxacin® (AR); Utibid® (RO); Utin-400® (ZA); Utinor® (GB, IT); Xacin® (TH); Xasmun® (ES); Zoroxin® (AT, BE, CR, DK, GT, HN, LU, PA, SV)

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