title: Norfloxacin nicotinate pharmacokinetics in unweaned and weaned calves.
abstract: The pharmacokinetics of norfloxacin nicotinate were investigated in unweaned and weaned calves. Following intravenous administration of 7.5 and 15 mg/kg (calculated as norfloxacin base) the clearance values were 8.5 +/- 2.0 or 7.7 +/- 1.2 mL/min.kg (unweaned calves) and 11.7 +/- 3.2 or 16.1 +/- 3.3 mL/min.kg (weaned calves). Norfloxacin mean residence time and volume of distribution values were 211 +/- 33 or 227 +/- 41 min (unweaned calves) and 185 +/- 79 or 128 +/- 18 minutes (weaned calves), and 1.8 +/- 0.3 or 1.7 +/- 0.1 L/kg (unweaned calves) and 2.0 +/- 0.7 or 2.1 +/- 0.7 L/kg (weaned calves) following administration of the lower and higher dose, respectively. These results indicated that norfloxacin pharmacokinetics were similar at a dose range of 7.5-15 mg/kg. However, a significant difference was observed in clearance, mean residence time and the half-life values between the unweaned and weaned calves. The only major pharmacokinetic parameter which did not show a significant difference between the investigated groups was the volume of distribution. The pharmacokinetic differences between the non-ruminating (unweaned) and ruminating (weaned) animals seemed to result from changes in drug clearance. The absorption rate after intramuscular administration appeared to change as a result of dose increase. Norfloxacin bioavailability following intramuscular administration ranged from 73 to 106%. The results suggested that larger injection volumes may reduce the extent of absorption.
authors: National Residue Control Laboratory, Ministry of Agriculture, Kimron Veterinary Institute, Beit Dagan, Israel.
authors: M
authors: M
authors: Gips
authors: S
authors: S
authors: Soback
mesh_terms: D000042:Absorption; D000818:Animals; D000833:Animals, Suckling / Q000378:metabolism*; D000890:Anti-Infective Agents / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D019540:Area Under Curve; D001665:Binding Sites; D001682:Biological Availability; D002417:Cattle / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D005260:Female; D024841:Fluoroquinolones; D007273:Injections, Intramuscular / Q000662:veterinary; D007275:Injections, Intravenous / Q000662:veterinary; D009539:Nicotinic Acids / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics; D009643:Norfloxacin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics; D012015:Reference Standards; D014886:Weaning
chemical_list: D000890:Anti-Infective Agents; D024841:Fluoroquinolones; D009539:Nicotinic Acids; C089868:norfloxacin nicotinate; D009643:Norfloxacin