Evaluation of plasma concentration after intravenous and intramuscular penicillin administration over 24 hr in healthy adult horses.

This research investigates the effectiveness of a combined intravenous and intramuscular administration method of penicillin in horses, showing that this method can maintain effective plasma penicillin concentrations.

Introduction to the Study

• The paper presents outcomes from a study centered on the use of penicillin in horses. Penicillin is frequently administered in horses either intravenously (IV) or intramuscularly (IM), aiming to prevent or treat infections.
• However, both of these administration methods come with shortcomings. One of the primary issues is maintaining effective penicillin levels in the blood over an extended period.
• To address these drawbacks, the researchers have developed a 24-hour hybrid administration protocol (HPP). This protocol combines the IV and IM delivery methods.

Methodology

• The researchers administered IV potassium penicillin G at two time intervals (0 and 6 hours) and IM procaine penicillin G at 12 hours to seven healthy horses.
• They collected venous blood samples at two-hour intervals within a 20-hour period and again at 24 hours.
• These samples were then analyzed using liquid chromatography and mass spectrometry to measure penicillin concentrations.
• The researchers also tested the susceptibility of equine isolates to penicillin to establish pharmacodynamic targets.

Results

• The Minimum Inhibitory Concentration (MIC) of penicillin for 264 isolates of Streptococcus species was discovered to be lesser or equal to 0.06 µg/ml.
• The mean plasma penicillin concentration was higher than 0.07 µg/ml on applying the 24-hour dosing interval. It implies that this level of concentration was maintained for most horses for nearly the entire period.
• However, two horses could only maintain this concentration for 52%-65% of the dosing interval, indicating variable results in individual horses.

Conclusion

• The researchers concluded that the hybrid administration method had positive results in maintaining a useful level of plasma penicillin concentration over a 24-hour period.
• Nevertheless, the variation in individual results cannot be dismissed and calls for further clinical studies to investigate these differences.