GYRABLOCK Film-coated tablet Ref.[28302] Active ingredients: Norfloxacin

Absorption of norfloxacin is rapid following oral administration, with peak serum levels being reached after about one hour. Between 30% - 40% of the dose is absorbed, the serum half life is about four hours and is dose independent. In renal impairment the half life is prolonged to about eight hours. Norfloxacin penetrates the renal parenchyma, prostate gland, testicle, uterus, cervix and bile.

Elimination of norfloxacin is by metabolism, biliary excretion and renal excretion. Renal excretion is by both net tubular secretion and glomerular filtration. Urinary excretion is of both norfloxacin, over 70%, and six metabolites with lesser antimicrobial activity. Urine pH does not affect activity. It is less than 15% protein bound.

Dogs, three to five months old, administered norfloxacin at levels four or more times greater than the usual human dose suffered from blister formation and the eventual erosion of the articular cartilage of load bearing joints. Dogs older than six months did not suffer this.

Teratogenic or foetotoxic effects were not observed in teratology studies in mice and rats and fertility studies in mice, using oral doses 30 to 50 times greater than the usual human dose. In rabbits dosed at 100mg/kg/day, embryotoxicity secondary to maternal toxicity was observed. This is a non specific antimicrobial effect in rabbit due to sensitivity to gut flora changes. Cynomolgus monkeys dosed at several times human dose did not show evidence of teratogenicity but did suffer greater embryonic loss. The relevance of these animal studies to humans is unclear.