Active ingredient: Norfloxacin. Chemical name: 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl) -3- quinoline carboxylic acid Structural formula: Molecular formula: C16H18FN3O3 Molecular Weight: 319.34 CAS: 70458-96-7
Norfloxacin is a white to pale yellow crystalline powder. It is freely soluble in glacial acetic acid, and very slightly soluble in ethanol, methanol and water. It has a melting point of approximately 221C. Norfloxacin, a fluoroquinolone, differs from quinolones by having a fluorine atom at the 6 position and a piperazine moiety at the 7 position. Examples of antibacterial drugs which are quinolones include nalidixic acid and cinoxacin. Each tablet of Nufloxib contains 400 mg of norfloxacin and the following inactive ingredients: microcrystalline cellulose, croscarmellose sodium, colloidal anhydrous silica, magnesium stearate, hypromellose, titanium dioxide, propylene glycol, lactose, macrogol 4000, and talc - purified.
Synthetic antibacterial agent for oral administration; a fluoroquinolone.
Norfloxacin has in vitro activity against a broad spectrum of Gram-negative and some Gram- positive aerobic bacteria. Norfloxacin inhibits bacterial deoxyribonucleic acid synthesis and is bactericidal. At the molecular level three specific events are attributed to norfloxacin in Escherichia coli cells: inhibition of the ATP dependent DNA supercoiling reaction catalysed by DNA gyrase; inhibition of the relaxation of supercoiled DNA; promotion of double stranded DNA breakage. Resistance to norfloxacin due to spontaneous mutation in vitro is a rare occurrence (range: 10-9 to 10-12 cells). Resistance of the organism has developed during therapy with norfloxacin in less than 1% of patients treated. Organisms in which development of resistance is greatest are the following: Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter sp., Enterococci. For this reason, when there is a lack of satisfactory clinical response, culture and susceptibility testing should be repeated. Norfloxacin is active in vitro against the following organisms. Bacteria found in urinary tract infections. Aerobic bacteria. Gram-positive bacteria including Streptococcus faecalis (Enterococcus), Staphylococcus aureus, Staph. epidermidis, Staph. saprophyticus. Gram-negative bacteria including Citrobacter diversus, C. freundii, Enterobacter cloacae, Escherichia coli, Klebsiella oxytoca, K. pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa. Bacteria found in gastrointestinal infections. Shigella, E. coli, Salmonella typhi. In addition, norfloxacin is active against Neisseria gonorrhoeae. Norfloxacin is not generally active against obligate anaerobes. Nalidixic acid resistant organisms are generally susceptible to norfloxacin in vitro; however, these organisms may have higher minimum inhibitory concentrations (MIC) to norfloxacin than nalidixic acid susceptible strains. There is generally no cross resistance between norfloxacin and other classes of antibacterial agents. Therefore, norfloxacin often demonstrates activity against indicated organisms resistant to the aminoglycosides (including gentamicin), penicillins, cephalosporins, tetracyclines, macrolides and sulfonamides, including combinations of sulfamethoxazole and trimethoprim. Antagonism has been demonstrated in vitro between norfloxacin and nitrofurantoin.
Dilution or diffusion techniques - either quantitative (MIC) or breakpoint, should be used following a regularly updated, recognised and standardised method (e.g. NCCLS). Standardised susceptibility test procedures require the use of laboratory control microorganisms to control the technical aspects of the laboratory procedures. A report of "Susceptible" indicates that the pathogen is likely to be inhibited if the antimicrobial compound in the blood reaches the concentrations usually achievable. A report of "Intermediate" indicates that the result should be considered equivocal, and if the microorganism is not fully susceptible to alternative, clinically feasible drugs, the test should be repeated. This category implies possible clinical applicability in body sites where the drug is physiologically concentrated or in situations where high dosage of drug can be used. This category also provides a buffer zone, which prevents small-uncontrolled technical factors from causing major discrepancies in interpretation. A report of "Resistant" indicates that the pathogen is not likely to be inhibited if the antimicrobial compound in the blood reaches the concentrations usually achievable; other therapy should be selected. Note: the prevalence of resistance may vary geographically for selected species and local information on resistance is desirable, particularly when treating severe infections.
Norfloxacin and related drugs have been shown to cause arthropathy in immature animals of most species tested (see PRECAUTIONS). Crystalluria has occurred in laboratory animals tested with norfloxacin. In dogs, needle shaped drug crystals were seen in the urine at doses of 50 mg/kg/day. In rats, crystals were reported following doses of 200 mg/kg/day. Embryo lethality and slight maternotoxicity (vomiting and anorexia) were observed in cynomolgus monkeys at doses of 150 mg/kg/day or higher. Ocular toxicity, seen with some related drugs, was not observed in any norfloxacin treated animals.
In fasting healthy volunteers, approximately 30 to 40% of an oral dose of norfloxacin is absorbed. Absorption is rapid following single doses of 200 and 400 mg. At the respective doses, mean peak serum and plasma concentrations of 0.8 and 1.5 microgram/mL are attained approximately one hour after dosing. The presence of food may decrease absorption. The effective half-life of norfloxacin in serum and plasma is three to four hours. Steady-state concentrations of norfloxacin will be attained within two days of dosing. The absorbed norfloxacin is eliminated mainly through renal excretion. Renal excretion occurs by both glomerular filtration and tubular secretion as evidenced by the high rate of renal clearance (approximately 275 mL/minute). Within 24 hours of drug administration, 26 to 32% of the administered dose is recovered in the urine as norfloxacin with an additional 5 to 8% being recovered in the urine as six metabolites of considerably less antimicrobial potency. However, urinary recovery may occasionally be very low. Only a small percentage (less than 1%) of the dose is recovered thereafter. Two to three hours after a single 400 mg dose, urinary concentrations of 200 microgram/mL or more are attained in the urine. In healthy volunteers, mean urinary concentrations of norfloxacin remain above 30 microgram/mL for approximately twelve 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 solubility increasing at pHs above and below this value. The disposition of norfloxacin in patients with creatinine clearance rates greater than 30 mL/minute/1.73 m2 is similar to that in healthy volunteers. In patients with creatinine clearance rates equal to or less than 30 mL/minute/1.73 m2, the renal elimination of norfloxacin decreases so that the effective serum half-life is 8.6 to 11.5 hours. In these patients, alteration of dosage is necessary (see DOSAGE AND ADMINISTRATION). Drug absorption appears unaffected by decreasing renal function. In healthy elderly volunteers (65 to 75 years of age with normal renal function for their age), norfloxacin is eliminated more slowly because of their slightly decreased renal function. Drug absorption appears unaffected. The effective half-life of norfloxacin in these elderly subjects is four hours. Faecal recovery accounts for another 30% of the administered dose. This represents the unabsorbed drug along with a small contribution through biliary excretion. After a single 400 mg dose of norfloxacin, mean antimicrobial activities equivalent to norfloxacin 278, 773 and 82 microgram/g of faeces were obtained at 12, 24 and 48 hours, respectively. The serum protein binding of norfloxacin is between 10 and 15%.
Treatment of adults with complicated and uncomplicated urinary tract infections that are caused by susceptible strains of microorganisms. Treatment of adults with gastrointestinal infections, in particular shigellosis and traveller's diarrhoea.
Note.
Specimens for culture and susceptibility testing should be obtained prior to and during treatment if clinical response warrants.
Suppression, in adults, of chronic, recurrent urinary tract infection.
Hypersensitivity to any component of this product or any chemically related quinolone antibacterials. Children (Paediatric patients, adolescents [under the age of 18]) Pregnancy
Needle shaped crystals were found in the urine of some volunteers who received either placebo, norfloxacin 800 mg or norfloxacin 1,600 mg (at or twice the recommended daily dose, respectively) while participating in a double blind, crossover study comparing single doses of norfloxacin with placebo. While crystalluria is not expected to occur under usual conditions with a dosage regimen of 400 mg twice daily, as a precaution, the daily recommended dosage should not be exceeded and the patient should drink sufficient fluids to ensure a proper state of hydration and adequate urinary output. Antibiotic associated pseudomembranous colitis has been reported with nearly all antibiotics including norfloxacin. A toxin produced with Clostridium difficile appears to be the primary cause. The severity of the colitis may range from mild to life-threatening. It is important to consider this diagnosis in patients who develop diarrhoea or colitis in association with antibiotic use (this may occur up to several weeks after cessation of antiobiotic therapy). Mild cases usually respond to drug discontinuation alone. However, in moderate to severe cases appropriate therapy with a suitable oral antibacterial agent effective against Cl. difficile should be considered. Fluids, electrolytes and protein replacement should be provided when indicated. Drugs which delay peristalsis, e.g. opiates and diphenoxylate with atropine (Lomotil) may prolong and/or worsen the condition and should not be used. The effects of norfloxacin on brain function or on the electrical activity of the brain have not been tested. Convulsions have been reported rarely in patients receiving norfloxacin. As with other organic acids, norfloxacin should be used with caution in individuals with a history of convulsions or known factors that predispose to seizures. Photosensitivity reactions have been observed in patients who are exposed to excessive sunlight while receiving some members of this drug class. Excessive sunlight should be avoided. Therapy should be discontinued if photosensitivity occurs. Achilles and other tendon ruptures that required surgical repair or resulted in prolonged disability have been reported with norfloxacin and other quinolones. Norfloxacin should be discontinued if the patient experiences pain, inflammation or rupture of a tendon. The oral administration of single doses of norfloxacin 100 mg/kg caused lameness in immature dogs. Histological examination of the weight bearing joints of these dogs revealed permanent lesions of the cartilage. Related drugs (e.g. nalidixic acid and cinoxacin) also produced erosions of the cartilage in weight bearing joints and other signs of arthropathy in immature animals of various species. Rarely, haemolytic reactions have been reported in patients with latent or actual defects in glucose-6-phosphate dehydrogenase activity who take quinolone antibacterial agents, including norfloxacin (see ADVERSE EFFECTS). Quinolones, including norfloxacin, may exacerbate the signs of myasthenia gravis and lead to life-threatening weakness of the respiratory muscles. Caution should be exercised when using quinolones, including norfloxacin, in patients with myasthenia gravis (see ADVERSE EFFECTS). Some quinolones have been associated with prolongation of the QT interval on the electrocardiogram and infrequent cases of arrhythmias. During post-marketing surveillance, extremely rare cases of torsades de pointes have been reported in patients taking norfloxacin. These reports generally involve patients who had other concurrent medical conditions and the relationship to norfloxacin has not yet been established. Among drugs known to cause prolongation of the QT interval, the risk of arrhythmias may be reduced by avoiding use in the presence of hypokalaemia, significant bradycardia, or concurrent treatment with class Ia or class III antiarrhythmic agents. Quinolones should also be used with caution in patients using cisapride, erythromycin, antipsychotics, tricyclic antidepressants or have any personal or family history of QTc prolongation.
Alteration in dosage regimen is necessary for patients with impaired renal function (see DOSAGE AND ADMINISTRATION).
Information is not available at present on the carcinogenic potential of norfloxacin. Norfloxacin was tested for mutagenic activity in a number of in vivo and in vitro tests. Norfloxacin had no mutagenic effect in the dominant lethal test in mice and did not cause chromosomal aberrations in hamsters or rats at 500 to 1,000 mg/kg/day. Norfloxacin had no mutagenic activity in vitro in the Ames microbial mutagen test and V-79 mammalian cell assay. Although norfloxacin was weakly positive in the Rec-assay for DNA repair, all other mutagenic assays were negative including a more sensitive test (V-79). Norfloxacin did not adversely affect the fertility of male and female mice at oral doses up to 500 mg/kg/day.
Norfloxacin has been shown to produce embryonic loss in cynomolgus monkeys when given in doses of 150 mg/kg/day with peak plasma levels that are two to three times those obtained in humans. There has been no evidence of a teratogenic effect in any of the animal species tested (rat, rabbit, mouse, monkey) at 100 to 800 mg/kg/day. There were no adequate and well controlled studies in pregnant women. Since norfloxacin, like other drugs in this class, causes arthropathy in immature animals, it should not be used in pregnant women (see CONTRAINDICATIONS).
It is not known whether norfloxacin is excreted in human milk. When a 200 mg dose of norfloxacin was administered to breastfeeding mothers, norfloxacin was not detected in human milk. However, because the dose studied was low, because other drugs in this class are secreted in human milk, and because of the potential for serious adverse effects from norfloxacin in breastfed infants, a decision should be made to discontinue breastfeeding or to discontinue the drug at least 24 to 48 hours before restarting breastfeeding, taking into account the importance of the drug to the mother.
As with other quinolones, norfloxacin has been shown to cause arthropathy in immature animals. The safety of norfloxacin in children has not been adequately explored and therefore norfloxacin is not to be used in prepubertal children or growing adolescents (see CONTRAINDICATIONS).
Norfloxacin may cause dizziness or lightheadedness; therefore, patients should know how they react to norfloxacin before they operate a vehicle or machinery or engage in activities requiring mental alertness and coordination.
Patients should be advised to take norfloxacin one hour before or two hours after a meal. Patients should also be advised to drink fluids liberally and not to take antacids concomitantly or within two hours after dosing.
Diminished urinary excretion of norfloxacin has been reported during the concomitant administration of probenecid and norfloxacin. The concomitant use of nitrofurantoin is not recommended since nitrofurantoin may antagonise the antibacterial effect of norfloxacin in the urinary tract. Quinolones, including norfloxacin, have been shown in vitro to inhibit CYP1A2. Concomitant use with drugs metabolised by CYP1A2 (e.g. 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. Some quinolones, including norfloxacin, have also been shown to interfere with the metabolism of caffeine. This may lead to reduced clearance of caffeine and a prolongation of its plasma half-life that may lead to accumulation of caffeine in plasma when products containing caffeine are consumed while taking norfloxacin. Elevated plasma levels of theophylline have been reported with concomitant quinolone use. There have been rare reports of theophylline related side effects in patients on concomitant therapy with norfloxacin and theophylline. Therefore, monitoring of theophylline plasma levels should be considered and dosage of theophylline adjusted as required. Elevated serum levels of cyclosporin have been reported with concomitant use with norfloxacin. Therefore, cyclosporin serum levels should be monitored and appropriate cyclosporin dosage adjustments made when these drugs are used concomitantly. Quinolones, including norfloxacin, may enhance the effects of the oral anticoagulant warfarin or its derivatives (e.g. phenprocoumon, acenocoumarol) and phenindione or similar agents. When these products are administered concomitantly, prothrombin time or other suitable coagulation tests should be closely monitored. The concomitant administration of quinolones including norfloxacin with glibenclamide (a sulfonylurea agent) has, on rare occasions, resulted in severe hypoglycaemia. Therefore, monitoring of blood glucose is recommended when these agents are co-administered. Multivitamins, calcium preparations, products containing iron or zinc, antacids or sucralfate should not be administered concomitantly with, or within two hours, of the administration of norfloxacin because they may interfere with absorption, resulting in lower serum and urine levels of norfloxacin. Videx (didanosine) chewable/ buffered tablets or the paediatric powder for oral solution should not be administered concomitantly with, or within two hours of, the administration of norfloxacin, because these products may interfere with absorption resulting in lower serum and urine levels of norfloxacin. 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, Nufloxib should be used with caution in individuals receiving NSAIDs concomitantly. Animal data have shown that quinolones in combination with fenbufen can lead to convulsions. Therefore, concomitant administration of quinolones and fenbufen should be avoided. Lowered bioavailability of mycophenolic acid was observed in healthy volunteers receiving combined treatment with norfloxacin and metronidazole.
In clinical trials, norfloxacin was generally well tolerated. The incidence of subjects reporting drug related adverse experiences in clinical trials involving 1,127 subjects was 3.4%. However, the overall incidence was 10.7% and the figures below were calculated without reference to drug relationship. Most adverse effects occur within the first few days of therapy. The most common adverse experiences (1 to 3%) were either gastrointestinal or neurological: nausea 2.8%, headache 2.7% and dizziness 1.8%. Additional effects (0.3 to 1%) were: fatigue, rash, abdominal pain, dyspepsia, somnolence, depression, insomnia, constipation, flatulence and heartburn. Less frequent effects included: dry mouth, diarrhoea, fever, vomiting, erythema, euphoria, anxiety, irritability, hallucinations, altered taste, vaginal swelling and tendonitis. Visual disturbances have been reported with drugs in this class. Abnormal laboratory values observed in these 1,127 subjects in clinical trials were eosinophilia 1.8%, elevation of ALT (SGPT) and AST (SGOT) 1.8%, increased alkaline phosphatase 1.4%, and decreased white blood cell or neutrophil count 1.2%. Those occurring less frequently included increased serum urea, serum creatinine and lactate dehydrogenase (LDH), and decreased haematocrit.
Postmarketing
The following additional adverse effects have been reported since the drug was marketed.
Hypersensitivity reactions.
These include anaphylaxis, angioedema, dyspnoea, vasculitis, urticaria, arthritis, myalgia, arthralgia, interstitial nephritis.
Skin.
Photosensitivity, Stevens-Johnson syndrome, toxic epidermal necrolysis, exfoliative dermatitis, erythema multiforme, pruritus.
Central nervous system.
Confusion, paraesthesia, polyneuropathy including Guillain-Barre syndrome, hypoesthesia, psychic disturbances including psychotic reactions, convulsions, tremors and myoclonus.
Liver, gastrointestinal.
Pseudomembranous colitis, pancreatitis (rare), hepatitis, including jaundice and cholestatic jaundice, elevated liver function tests.
Musculoskeletal.
Tendinitis, tendon rupture, exacerbation of myasthenia gravis, elevated creatine kinase (CK).
Haematological.
Agranulocytosis, thrombocytopenia, haemolytic anaemia, sometimes associated with glucose-6-phosphate dehydrogenase deficiency.
Genitourinary.
Vaginal candidiasis.
Renal function.
Renal failure.
Special senses.
Dysgeusia, visual disturbances, hearing loss.
Causal relationship unknown
A definite causal relationship could not be established with regard to the following adverse effects: conjunctivitis, eye pain/irritation and asthenia. On very rare occasions, prolonged QTc interval and ventricular arrhythmia (including torsades de pointes), hypertonia, ataxia, dysarthria, dysphasia, haemophthalmia, nystagmus, periorbital erythema and, proteinuria have been reported.
Norfloxacin tablets should be taken one hour before or two hours after a meal with a glass of water. Patients receiving norfloxacin should be well hydrated. Multivitamins, calcium preparations, other products containing iron or zinc, antacids containing magnesium and aluminium, sucralfate or Videx (didanosine), chewable/ buffered tablets or the paediatric powder for oral solution, should not be taken within two hours of administration of norfloxacin (see PRECAUTIONS). Nufloxib tablets should not be halved.
Normal renal function.
The recommended dosage of Norfloxacin for the treatment of urinary tract infection is 400 mg twice daily for seven to ten days.
For uncomplicated lower urinary tract infections, the recommended dosage is 400 mg twice daily for three days. In one study of uncomplicated lower urinary tract infections, treatment for seven days resulted in somewhat better eradication rates than treatment for three days. For suppression in chronic, recurrent urinary tract infection, 400 mg twice daily may be administered for four to twelve weeks. Maximum total daily dosage should not exceed 800 mg per day. Impaired renal function. Norfloxacin may be used for the treatment of urinary tract infections in patients with renal insufficiency. In patients with a creatinine clearance rate of 30 mL/minute/1.73 m2 or less, the recommended dosage is one 400 mg tablet once daily for the duration given above. At this dosage, the urinary concentration exceeds the MICs for most urinary pathogens susceptible to norfloxacin, even when the creatinine clearance is less than 10 mL/minute/1.73 m2. However, such patients should be observed carefully for adverse effects due to possible drug retention. When only the serum creatinine level is available, the following formula (based on sex, weight and age of the patient) may be used to convert this value into creatinine clearance. The serum creatinine should represent a steady state of renal function.
Men: Bodyweight (kg) x (140 - age in years) x 0.0885 72 x serum creatinine (mmol/L) Women: Multiplication of the result of the above equation by 0.85
Elderly patients with a creatinine clearance of greater than 30 mL/minute/1.73 m2 should receive the dosages recommended under Normal renal function. Elderly patients with a creatinine clearance of 30 mL/minute/1.73 m2 or less should receive 400 mg once daily as recommended under Impaired renal function.
(Shigellosis, traveller's diarrhoea.) The recommended dosage is 400 mg twice daily for five days.
The acute oral LD50 values in male and female mice and male and female rats were greater than 4 g/kg.
Treatment
In the event of acute overdosage, the patient should be carefully observed and given symptomatic and supportive treatment. Adequate hydration must be maintained. Contact the Poisons Information Centre on 131126 (Australia) for advice on the management of overdosage.
400 mg - White, oval, biconvex film coated tablets; blister packs of 14. Store below 25C.
S4 (Prescription Only Medicine)
Chase Building 2 Wentworth Park Road
NSW 2037
ABN 93 002 359 739 www.alphapharm.com.au
Approved by the Therapeutic Goods Administration on 25 January 2008. Date of most recent amendment: 25 August 2009.