Plasma concentration of gentamicin after intramuscular or subcutaneous administration to horses.

This research investigates the effects of administering the antibiotic gentamicin to horses either intramusically (IM) or subcutaneously (SC). This includes understanding the drug’s absorption and bioavailability, particularly in comparison to intravenous (IV) administration which has been previously studied.

Background

• The authors note that while the pharmacokinetics and bioavailability of gentamicin have been studied for IV and IM administration, little research has been done on SC administration in horses.
• The method of administration can greatly influence a drug’s systemic bioavailability, as determined by drug release from the injection site, absorption, and method of diffusion in the body.
• Intramuscular injections are often complicated by factors such as pain, discomfort, temporary lameness and paralysis, and injection site variation that can lead to up to 30% variation in drug systemic bioavailability.
• The authors note that repeated intramuscular injections can be a source of anxiety for horses and present handling difficulties for veterinary personnel.

Research Objective

• Given the identified issues with IM injection, the authors looked to explore the feasibility of SC administration of gentamicin in horses.
• However, the authors were unable to find any existing research on the subcutaneous administration of antibiotics in horses, hence the need for this study.
• They note that clinicians often believe antibiotics administered SC are not well absorbed or tolerated by horses, and this study aims to evaluate the validity of this belief.
• The focus of the research was to compare the systemic bioavailability of gentamicin between IM and SC routes, using plasma concentration-time curves and area under the curve measurements.

Research Methodology

• The study was a crossover design, using six clinically healthy horses aged 6 to 12 years.