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Pharmacokinetics of penicillin G procaine versus penicillin G potassium and procaine hydrochloride in horses

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  • 1 Pennsylvania Equine Toxicology and Research Laboratory, West Chester University, Department of Chemistry, West Chester, PA 19382.
  • | 2 School of Veterinary Medicine, New Bolton Center, University of Pennsylvania, Kennett Square, PA 19348.
  • | 3 School of Veterinary Medicine, New Bolton Center, University of Pennsylvania, Kennett Square, PA 19348.
  • | 4 School of Veterinary Medicine, New Bolton Center, University of Pennsylvania, Kennett Square, PA 19348.
  • | 5 School of Veterinary Medicine, New Bolton Center, University of Pennsylvania, Kennett Square, PA 19348.
  • | 6 School of Veterinary Medicine, New Bolton Center, University of Pennsylvania, Kennett Square, PA 19348.
  • | 7 School of Veterinary Medicine, New Bolton Center, University of Pennsylvania, Kennett Square, PA 19348.
  • | 8 Pennsylvania Equine Toxicology and Research Laboratory, West Chester University, Department of Chemistry, West Chester, PA 19382.
  • | 9 Pennsylvania Equine Toxicology and Research Laboratory, West Chester University, Department of Chemistry, West Chester, PA 19382.

Abstract

Objective—To compare the pharmacokinetics of penicillin G and procaine in racehorses following IM administration of penicillin G procaine (PGP) with pharmacokinetics following IM administration of penicillin G potassium and procaine hydrochloride (PH).

Animals—6 healthy adult mares.

Procedure—Horses were treated with PGP (22,000 units of penicillin G/kg of body weight, IM) and with penicillin G potassium (22,000 U/kg, IM) and PH (1.55 mg/kg, IM). A minimum of 3 weeks was allowed to elapse between drug treatments. Plasma and urine penicillin G and procaine concentrations were measured by use of high-pressure liquid chromatography.

Results—Median elimination phase half-lives of penicillin G were 24.7 and 12.9 hours, respectively, after administration of PGP and penicillin G potassium. Plasma penicillin G concentration 24 hours after administration of penicillin G potassium and PH was not significantly different from concentration 24 hours after administration of PGP. Median elimination phase halflife of procaine following administration of PGP (15.6 hours) was significantly longer than value obtained after administration of penicillin G potassium and PH (1 hour).

Conclusions and Clinical Relevance—Results suggest that IM administration of penicillin G potassium will result in plasma penicillin G concentrations for 24 hours after drug administration comparable to those obtained with administration of PGP. Clearance of procaine from plasma following administration of penicillin G potassium and PH was rapid, compared with clearance following administration of PGP. (Am J Vet Res 2000;61:811–815)

Abstract

Objective—To compare the pharmacokinetics of penicillin G and procaine in racehorses following IM administration of penicillin G procaine (PGP) with pharmacokinetics following IM administration of penicillin G potassium and procaine hydrochloride (PH).

Animals—6 healthy adult mares.

Procedure—Horses were treated with PGP (22,000 units of penicillin G/kg of body weight, IM) and with penicillin G potassium (22,000 U/kg, IM) and PH (1.55 mg/kg, IM). A minimum of 3 weeks was allowed to elapse between drug treatments. Plasma and urine penicillin G and procaine concentrations were measured by use of high-pressure liquid chromatography.

Results—Median elimination phase half-lives of penicillin G were 24.7 and 12.9 hours, respectively, after administration of PGP and penicillin G potassium. Plasma penicillin G concentration 24 hours after administration of penicillin G potassium and PH was not significantly different from concentration 24 hours after administration of PGP. Median elimination phase halflife of procaine following administration of PGP (15.6 hours) was significantly longer than value obtained after administration of penicillin G potassium and PH (1 hour).

Conclusions and Clinical Relevance—Results suggest that IM administration of penicillin G potassium will result in plasma penicillin G concentrations for 24 hours after drug administration comparable to those obtained with administration of PGP. Clearance of procaine from plasma following administration of penicillin G potassium and PH was rapid, compared with clearance following administration of PGP. (Am J Vet Res 2000;61:811–815)