Work

Pharmacokinetics and Safety of a Single Subcutaneous or Intramuscular Dose of Ketamine in Healthy Horses

Year: 2025

Type: article

Abstract: Pharmacokinetics (PK) of intramuscular (IM) and subcutaneous (SC) ketamine in horses has not been described. This study aimed to evaluate the PK and safety of ketamine and its metabolites after a single SC or IM administration. In Phase 1, two horses received 0.5 or 1 mg/kg of ketamine via SC and IM routes. In Phase 2, eight horses received 0.5 mg/kg IM. Plasma or serum concentrations of ketamine and major metabolites were determined by a validated liquid chromatography-mass spectrometry method at baseline and selected intervals post-administration. Subcutaneous administration resulted in extremely low concentrations (< 5 ng/mL). Phase 2 focused only on IM administration. Median peak serum ketamine concentrations after IM administration were 20.9 ng/mL (IQR 15.2-35.9) with a time to peak drug concentration of 1.4 h (IQR = 0.8-1.9 h) and terminal half-life of 1.8 h (IQR = 1.3-2.6 h). No changes in physical examination or laboratory parameters were observed. Ketamine metabolites were detected within 5 min after IM administration, with norketamine as the predominant metabolite. A single IM administration in healthy horses resulted in rapid absorption and variable inter-individual concentrations without adverse effects. Future studies should investigate repeated IM dosing and determine therapeutic plasma concentrations in horses.

Source: Journal of Veterinary Pharmacology and Therapeutics

DOI: 10.1111/jvp.70037

Authors: Ana Rangel, Debra C. Sellon, Macarena G. Sanz, Erin Pinnell, Zuzanna M. Pietras, Nicolas F. Villarino

Institutions: Washington State University, Iowa State University

Language: English

Topic: Veterinary Pharmacology and Anesthesia

Subfield: Small Animals

Field: Veterinary

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: hybrid

Estimated APC paid: $4,520