Evaluation of the pharmacokinetics of imipenem following regional limb perfusion using the saphenous and the cephalic veins in standing horses.

The given research paper is about an experiment that was conducted to understand the effects of the drug imipenem when administered using intravenous regional limb perfusion (IV-RLP) to standing horses.

Research Context and Objective

• The need for this research arises from a desire to understand the pharmacokinetics of the imipenem drug, its distribution in the limb and its potential for treating severe distal limb infections in horses. It aims to measure how effectively the drug reaches the fetlock joint using different vein entry points (the cephalic and saphenous veins).

Methodology

• Nine horses were used for this experiment after getting approval from the University Animal Care and Use Committee.
• The researchers used random selection to decide whether to use a thoracic or pelvic limb on each horse.
• A bandage tourniquet (called Esmarch) was applied to the selected limb and the vein was catheterized.
• A solution with 500mg of imipenem was then injected through the catheter.
• To assess the amount of drug that reached the fetlock joint, synovial fluid samples were collected. Blood samples were also taken from the jugular vein for assessment.
• All samples were analyzed using liquid chromatography mass spectrometry, a technique that accurately measures the concentration of the drug.

Findings

• The study showed that the Cmax (peak serum concentration) of imipenem in the fetlock joint when using the cephalic vein was 87μg/mL. It was slightly lower (60μg/mL) when using the saphenous vein.

Implications

• The results suggest that using IV-RLP to administer imipenem through either of the tested veins can effectively deliver the drug to the fetlock joint.
• The drug concentrations achieved are well above the Minimum Inhibitory Concentration (MIC) required to act against most pathogens, including resistant bacteria such as MRSA and Pseudomonas aeruginosa.
• This suggests that judicious use of IV-RLP with imipenem can drastically increase the effectiveness of treatment for severe distal limb infections in horses.