Intramuscular bioavailability of ketoprofen lysine salt in horses.

The research article discusses a study investigating the intramuscular bioavailability, or the efficiency of an active substance to exert its effects when injected into muscle tissue, of ketoprofen administered in the form of a lysine salt in horses. The study findings indicate high bioavailability, slow absorption, and reduced tissue irritation at the injection site for the ketoprofen lysine salt, suggesting its viability for use in equine treatment.

Methodology

• The research conducted was a cross-over study using five horses as subjects.
• The treatment administered was ketoprofen, an anti-inflammatory drug, in lysine salt form.
• The ketoprofen was given both intravenously (directly into the bloodstream) and intramuscularly (into the muscle) at a dose of 2.2 mg/kg of the horse’s body mass.

Findings

• The study found that the absorption rate of ketoprofen when administered as a lysine salt intramuscularly was low. The mean residence time, or the average time the drug remains in the body, extended from 31.7 minutes when given intravenously to 128.9 minutes when given intramuscularly.
• Despite the slow absorption rate, the bioavailability of the drug was high (average 92.4%), indicating an effective transfer of the active substance from the injection site into the systemic circulation where it can exert its effects.
• The calculated steady-state plasma concentrations of ketoprofen, which reflect the amount of drug present in the body after repeated doses, were significantly higher after intramuscular injection than after intravenous administration.

Implications

• The findings suggest that intramuscular injections of ketoprofen lysine salt can be given to horses, which are especially susceptible to developing soft tissue reactions.
• The use of the lysine salt form of ketoprofen reduces local irritation at the injection site, making it a safer option for equine treatment.
• The slower absorption rate and higher steady-state plasma concentrations mean that the drug will stay in the body longer, potentially leading to prolonged effects and reducing the need for frequent dosing.