title: Disposition of penicillin G after administration of benzathine penicillin G, or a combination of benzathine penicillin G and procaine penicillin G in cattle.
abstract: Plasma concentration of penicillin G was evaluated in beef steers after administration of either a combination of benzathine penicillin G and procaine penicillin G in a 1:1 mixture at a dosage of 9,000 U/kg of body weight, IM (n = 5), 24,000 U/kg, IM (n = 5), or 8,800 U/kg, SC (n = 5), or benzathine penicillin G alone at a dosage of 12,000 U/kg, IM (n = 7). Plasma concentration of penicillin G was measured by use of a high-performance liquid chromatography assay that had a limit of determination of 0.005 microgram/ml. At a dosage for this combination of 9,000 U/kg IM, and 8,800 U/kg, SC, which are approved label recommendations in Canada, and the United States, respectively, mean (+/- SEM) peak plasma concentration was 0.58 (+/- 0.15) and 0.44 (+/- 0.02) microgram/ml, respectively. Although plasma penicillin concentration was quantifiable for 7 days in the steers that received 9,000 U/kg, IM, and for 4 days in the steers that received 8,800 U/kg, SC, the concentration was < 0.1 microgram/ml in both groups after the first 12 hours. After administration of the combination at dosage of 24,000 U/kg, IM, there was an initial peak plasma concentration at approximately 2 hours; thereafter, plasma concentration decreased slowly, with half-life of 58 hours. Although plasma penicillin G concentration was quantifiable for 12 days at this dosage, concentration was < 0.1 microgram/ml after the first 48 hours. After the initial 48 hours, plasma concentration of penicillin was of similar magnitude and decreased at similar rate for the combination at dosage of 24,000 U/kg and for 12,000 U/kg of benzathine penicillin G alone.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: College of Veterinary Medicine, North Carolina State University, Raleigh 27606.
authors.forename: M G
authors.initials: MG
authors.lastname: Papich
authors.forename: G O
authors.initials: GO
authors.lastname: Korsrud
authors.forename: J O
authors.initials: JO
authors.lastname: Boison
authors.forename: W D
authors.initials: WD
authors.lastname: Yates
authors.forename: J D
authors.initials: JD
authors.lastname: MacNeil
authors.forename: E D
authors.initials: ED
authors.lastname: Janzen
authors.forename: J J
authors.initials: JJ
authors.lastname: McKinnon
authors.forename: D A
authors.initials: DA
authors.lastname: Landry
mesh_terms: D000818:Animals; D002417:Cattle / Q000097:blood / Q000378:metabolism*; D004359:Drug Therapy, Combination / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics; D006207:Half-Life; D007273:Injections, Intramuscular; D007279:Injections, Subcutaneous; D007700:Kinetics; D008297:Male; D010400:Penicillin G / Q000097:blood / Q000493:pharmacokinetics*; D010401:Penicillin G Benzathine / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics; D010402:Penicillin G Procaine / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics
chemical_list: D010402:Penicillin G Procaine; D010400:Penicillin G; D010401:Penicillin G Benzathine