Norfloxacin

Fluoroquinolones may prolong QTc interval; avoid use in patients with a history of QTc prolongation, uncorrected hypokalemia, hypomagnesemia, or concurrent administration of other medications known to prolong the QT interval (including Class Ia and Class III antiarrhythmics, cisapride, erythromycin, antipsychotics, and tricyclic antidepressants).

Fluoroquinolones have been associated with the development of serious, and sometimes fatal, hypoglycemia. These events have occurred most often in elderly patients with diabetes, but have also been reported in patients without a prior history of diabetes. Prompt identification and treatment of hypoglycemia is essential. Individual quinolones may differ in their potential to cause this effect. It was most evident with gatifloxacin (no longer marketed as s systemic formulation). Hyperglycemia has also been associated with the use of fluoroquinolones. Patients should be monitored closely for signs/symptoms of disordered glucose regulation.

Severe hypersensitivity reactions, including anaphylaxis, have occurred with quinolone therapy. The spectrum of these reactions can vary widely; reactions may present as typical allergic symptoms (eg, itching, urticaria, rash, edema) after a single dose, or may manifest as severe idiosyncratic dermatologic (eg, Stevens-Johnson, toxic epidermal necrolysis), vascular (eg, vasculitis), pulmonary (eg, pneumonitis), renal (eg, nephritis), hepatic (eg, hepatic failure or necrosis), and/or hematologic (eg, anemia, cytopenias) events, usually after multiple doses. Prompt discontinuation of drug should occur if skin rash or other symptoms arise.

Avoid excessive sunlight and take precautions to limit exposure (eg, loose fitting clothing, sunscreen); may cause moderate-to-severe phototoxicity reactions. Discontinue use if photosensitivity occurs.

Fluoroquinolones are associated with disabling and potentially irreversible serious adverse reactions that may occur together, including tendinitis and tendon rupture, peripheral neuropathy, and CNS effects. Discontinue norfloxacin immediately and avoid use of fluoroquinolones in patients who experience any of these serious adverse reactions. Patients of any age or without pre-existing risk factors have experienced these reactions; may occur within hours to weeks after initiation. - CNS effects: Fluoroquinolones have been associated with an increased risk of CNS effects including seizures, increased intracranial pressure (including pseudotumor cerebri), and toxic psychosis; may also cause nervousness, agitation, insomnia, anxiety, nightmares, paranoia, dizziness, confusion, tremors, hallucinations, depression, and suicidal thoughts or actions. May occur following the first dose; discontinue immediately and avoid further use of fluoroquinolones in patients who experience these reactions. Use with caution in patients with known or suspected CNS disorder, or risk factors that may predispose to seizures or lower the seizure threshold. - Peripheral neuropathy: Fluoroquinolones have been associated with an increased risk of peripheral neuropathy; may occur soon after initiation of therapy and may be irreversible; discontinue if symptoms of sensory or sensorimotor neuropathy occur. Avoid use in patients who have previously experienced peripheral neuropathy. - Tendinitis/tendon ruptu

Prolonged use may result in fungal or bacterial superinfection, including C. difficile-associated diarrhea (CDAD) and pseudomembranous colitis; CDAD has been observed >2 months postantibiotic treatment. Disease-related concerns:

May exacerbate muscle weakness related to myasthenia gravis; avoid use in patients with known history of myasthenia gravis. Cases of severe exacerbations, including the need for ventilatory support and deaths have been reported.

Use caution with renal impairment; dose adjustment required. May increase risk of tendon rupture.

Use with caution in patients with rheumatoid arthritis; may increase risk of tendon rupture.

Since norfloxacin is ineffective in the treatment of syphilis and may mask symptoms, all patients should be tested for syphilis at the time of gonorrheal diagnosis and 3 months later. Concurrent drug therapy issues:

Potentially significant interactions may exist, requiring dose or frequency adjustment, additional monitoring, and/or selection of alternative therapy. Consult drug interactions database for more detailed information. Special populations:

Adverse effects (eg, tendon rupture, QT changes) may be increased in the elderly.

Hemolytic reactions may (rarely) occur with quinolone use in patients with latent or actual G6PD deficiency.

Safety and efficacy have not been established in children; other quinolones have caused transient arthropathy in children. Other warnings/precautions:

Reserve use of norfloxacin for treatment of uncomplicated urinary tract infections, including cystitis, for patients who have no alternative treatment options because of the risk of disabling and potentially serious adverse reactions (eg, tendinitis and tendon rupture, peripheral neuropathy, CNS effects).