title: Bioavailability and disposition of sodium and procaine penicillin G (benzylpenicillin) administered orally with milk to calves.
abstract: Eighteen 1-week-old Holstein calves were randomly assigned to one of three groups: (a) sodium penicillin G administered intravenously, (b) sodium penicillin G administered orally, or (c) procaine penicillin G administered orally. All calves were dosed with penicillin G at 4.0 mg/kg BW. At 5 weeks of age, the calves were dosed again. Blood samples were taken serially for 24 h after both dosings. Plasma was assayed for penicillin G by high performance liquid chromatography (HPLC). For i.v. administration, the area under the concentration-time curve (AUC), 7456 and 5508 ng/mL h, and systemic clearance, 0.54 and 0.73 L/kg h, were significantly different (P < 0.05) at 1 and 5 weeks of age, respectively. There were no significant differences between orally administered sodium and procaine penicillin G within the same age groups. Following oral (p.o.) administration, there were significant differences (P < 0.01) at 1 and 5 weeks of age in the AUC, 760 and 409 ng/mL h, terminal half-life, 2.1 and 1.6 h, time of maximum concentration (TMAX), 3.0 and 2.3 h, and maximum plasma concentration (CMAX), 85 and 58 ng/mL, respectively. Bioavailability was 10.2 and 7.4% at 1 and 5 weeks, respectively.
authors.affiliation: Department of Farm Animal Health and Resource Management, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA. jmusser@cvm.tamu.edu
authors.forename: J M
authors.initials: JM
authors.lastname: Musser
authors.forename: K L
authors.initials: KL
authors.lastname: Anderson
mesh_terms: D000284:Administration, Oral; D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D019540:Area Under Curve; D001682:Biological Availability; D002417:Cattle / Q000254:growth & development* / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid / Q000662:veterinary; D007275:Injections, Intravenous / Q000662:veterinary; D008892:Milk; D010400:Penicillin G / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D010402:Penicillin G Procaine / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D010406:Penicillins / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*
chemical_list: D010406:Penicillins; D010402:Penicillin G Procaine; D010400:Penicillin G