Norfloxacin

Indications

Oral
Uncomplicated gonorrhoea
Adult: 800 mg as a single daily dose.

CrCl (ml/min)	Dosage Recommendation
≤30	400 mg single dose

Oral
Chronic bacterial prostatitis
Adult: 400 mg bid for 28 days.

CrCl (ml/min)	Dosage Recommendation
≤30	400 mg once daily

Oral
Complicated urinary tract infections
Adult: 400 mg bid for 10-21 days.

CrCl (ml/min)	Dosage Recommendation
≤30	400 mg once daily

Oral
Chronic relapsing urinary tract infections
Adult: 400 mg bid for up to 12 wk, may be reduced to 400 mg once daily if adequate suppression within first 4 wk.

CrCl (ml/min)	Dosage Recommendation
≤30	400 mg once daily

Oral
Gastroenteritis
Adult: 400 mg bid for 3-5 days

CrCl (ml/min)	Dosage Recommendation
≤30	400 mg once daily

Oral
Uncomplicated urinary tract infections
Adult: Infections caused by susceptible Escherichia coli, Klebsiella pneumoniae, roteus mirabilis species: 400 mg bid for 3 days. Infections caused by other susceptible bacteria: 400 mg bid for 7-10 days.

CrCl (ml/min)	Dosage Recommendation
≤30	400 mg once daily

Ophthalmic
Conjunctivitis
Adult: As 0.3% solution: Usual dose, 1 or 2 drops in the eye 4 times daily for up to 7 days. Dosage may be increased to 1 or 2 drops every 2 hr for the 1^st day in more severe infections.
Child: ≥1 yr, as 0.3% solution: Usual dose, 1 or 2 drops in the eye 4 times daily for up to 7 days. Dosage may be increased to 1 or 2 drops every 2 hr for the 1^st day in more severe infections.

Special Populations: Reduce dose in patients with renal impairment: CrCl: ≤30 mL/min: 400 mg once daily.

Contraindications

Hypersensitivity to quinolones; children <18 yr. Lactation.

Warnings / Precautions

Renal impairment; history of CNS disorders; myasthaenia gravis. Pregnancy. QT prolongation; discontinue if signs of neuropathy occur.

Adverse Reactions

Nausea, vomiting, heartburn, constipation, diarrhoea, abdominal cramping, anorexia; headache, dizziness; depression, insomnia; phototoxicity; rash, fever, arthralgia; elevated liver enzymes, urea and creatinine. Eosinophilia, neutropenia, thrombocytopenia and anaemia; hyperhidris; tendon rupture; QT prolongation.
Potentially Fatal: Anaphylaxis, acute renal failure, seizures.

Overdose Reactions

Empty stomch by vomiting or gastric lavage. Give symptomatic and supportive treatment.

Drug Interactions

Antacids reduce absorption from GI tract. Probenecid reduces urinary excretion of norfloxacin. Norfloxacin may increase concentration of clozapine, ropinirole, tacrine, tizanidine. Severe hypoglycaemia has occured rarely with glyburide. Increased risk of CNS stimulation and seizures with NSAIDs.
Potentially Fatal: Raises theophylline and ciclosporin levels. Effects of warfarin potentiated. Risk of QT prolongation and torsades de pointes with class I and III antiarrythmics, cisapride, erythromycin, antipsychotics, TCAs.
See Below for More norfloxacin Drug Interactions

Food Interactions

Absorption reduced, especially when taken with dairy products e.g. milk or yogurt.

Mechanism of Actions

Norfloxacin inhibits the action of DNA gyrase in DNA replication, transcription, repair, recombination and transposition.
Absorption: 30-40% absorbed from the GI tract (oral); peak plasma concentrations after 1-2 hr. May be delayed by the presence of food.
Distribution: Genitourinary tract, placenta, bile (high concentrations). Protein-binding: 14%.
Metabolism: Hepatic; converted to several metabolites with antibacterial activity.
Excretion: Via urine by glomerular filtration and tubular secretion within 24 hr (30% as unchanged); via faeces (30%); 4 hr (elimination half-life); may be prolonged in renal impairment.

Administration

Should be taken on an empty stomach. (Take on an empty stomach 1 hr before or 2 hr after meals, w/ a glass of water. Ensure adequate hydration. Do not take w/ dairy products.)

Storage Conditions

Ophthalmic: Store at 15-30°C. Oral: Store at 15-30°C.

ATC Classification

J01MA06 - norfloxacin ; Belongs to the class of fluoroquinolones. Used in the systemic treatment of infections.
S01AX12 - norfloxacin ; Belongs to the class of other antiinfectives. Used in the treatment of eye infections.