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Pharmacologic class: Fluoroquinolone
Therapeutic class: Anti-infective
Pregnancy risk category C
FDA Box Warning
Fluoroquinolones for systemic use are associated with an increased risk of tendinitis and tendon rupture in all ages. This risk is further increased in patients usually over age 60, with concomitant use of corticosteroids, and in kidney, heart, and lung transplant recipients.
Drug may exacerbate muscle weakness in patients with myasthenia gravis. Avoid use in patients with known history of myasthenia gravis.
Inhibits bacterial DNA synthesis by blocking DNA gyrase in susceptible gram-negative and gram-positive aerobic and anaerobic bacteria
Tablets: 400 mg
Indications and dosages
➣ Urinary tract infections (UTIs) caused by Escherichia coli, Klebsiella pneumoniae, or Proteus mirabilis
Adults: 400 mg P.O. q 12 hours for 3 days
➣ UTIs caused by all organisms except E. coli, K. pneumoniae, and P. mirabilis
Adults: 400 mg P.O. q 12 hours for 7 to 10 days. For complicated UTIs, may give for up to 21 days.
Adults: 800 mg P.O. as a single dose
➣ Prostatitis caused by E. coli
Adults: 400 mg P.O. q 12 hours for 28 days
• Renal impairment
• Hypersensitivity to drug
• History of tendinitis or tendon rupture with fluoroquinolone use
Use cautiously in:
• CNS diseases or disorders, renal impairment, cirrhosis, bradycardia, acute myocardial ischemia
• known history of myasthenia gravis (avoid use)
• elderly patients
• pregnant or breastfeeding patients (safety not established except in postex-posure inhalation or cutaneous anthrax).
• children younger than age 18.
• Give with glass of water 1 hour before or 2 hours after a meal.
• Don't give antacids within 2 hours of norfloxacin.
CNS: dizziness, light-headedness, drowsiness, headache, asthenia, insomnia, agitation, confusion, acute psychoses, hallucinations, tremors, increased intracranial pressure, seizures
CV: vasodilation, QT prolongation, arrhythmias
GI: nausea, diarrhea, abdominal pain, pancreatitis, pseudomembranous colitis
GU: interstitial cystitis, vaginitis
Metabolic: hyperglycemia, hypoglycemia
Musculoskeletal: tendinitis, tendon rupture
Skin: rash, hyperhidrosis, photosensi-tivity, phototoxicity, Stevens-Johnson syndrome
Other: altered taste, myasthenia gravis exacerbation, hypersensitivity reactions including anaphylaxis
Drug-drug. Antacids, bismuth, iron salts, subsalicylate, sucralfate, zinc salts: decreased norfloxacin absorption
Antineoplastics: decreased norfloxacin blood level
Cimetidine: interference with norfloxacin elimination
Corticosteroids: increased risk of tendon rupture
Nitrofurantoin: antagonism of norfloxacin's antibacterial effects in GU tract
Other fluoroquinolones: increased risk of nephrotoxicity
Probenecid: decreased renal elimination of norfloxacin
Theophylline: increased theophylline blood level, greater risk of toxicity
Warfarin: increased anticoagulant effect
Drug-diagnostic tests. Alanine amino-transferase, alkaline phosphatase, aspartate aminotransferase, bilirubin, eosino-phils, lactate dehydrogenase, platelets: increased levels
Hemoglobin, hematocrit: decreased values
Drug-food. Caffeine: decreased hepatic metabolism of caffeine
Milk or yogurt (consumed alone): impaired drug absorption
Tube feedings: impaired drug absorption
Drug-herbs. Dong quai, St. John's wort: phototoxicity
Fennel: decreased drug absorption
Drug-behaviors. Sun exposure: phototoxicity
• Monitor vital signs and cardiovascular status.
• Check fluid intake and output. Keep patient well-hydrated.
Watch for signs and symptoms of tendinitis or tendon rupture.
• Assess patient's response to therapy. Obtain specimens for repeat culture and sensitivity tests if he relapses or doesn't improve.
• Monitor renal function.
• Tell patient to take on empty stomach with full glass of water, 1 hour before or 2 hours after a meal.
• If patient needs antacid for GI upset, instruct him not to take it within 2 hours of norfloxacin.
Advise patient to stop taking drug and promptly report rash; severe GI problems; tendon pain, swelling, or inflammation; or weakness.
• Caution patient to avoid driving and other hazardous activities until he knows how drug affects concentration and alertness.
• Teach patient ways to counteract photosensitivity, such as by wearing sunglasses and avoiding excessive exposure to bright light.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, foods, herbs, and behaviors mentioned above.