Distribution of penicillins into subcutaneous tissue chambers in ponies.

The research investigates how different penicillins distribute in implanted tissue chambers in ponies, and their dosage concentration over time. Ampicillin sodium, pivampicillin, and procaine penicillin G were used, their peak concentrations were monitored over 24 hours, and the effectiveness of these concentrations against a common bacterium was evaluated.

Objective and Methodology

• The study sought to understand the distribution of penicillins in subcutaneously implanted tissue chambers in ponies. These tissues were particularly chosen to study how these drugs interact with different tissues once introduced into the organism.
• The researchers used three different penicillins: Ampicillin sodium, Pivampicillin (a prodrug of Ampicillin), and Procaine penicillin G, each administered in different ways and in certain dosages.
• The study involved a total of six ponies for each medication, thus making it a sizable enough group for valid results.

Administration and Study Results

• Ampicillin sodium was administered intravenously at a dosage equivalent to 15 mg/kg of ampicillin. Peak concentration was reached approximately 1.7 hours after administration, with an average maximum concentration of 7.3 micrograms/mL in the tissue chamber fluid (TCF).
• Pivampicillin was given by nasogastric tube to ponies (who had eaten prior) at a dosage of 19.9 mg/kg – equivalent to 15 mg/kg of ampicillin. Maximum concentration of the drug was observed on average 2.7 hours post-administration, with the mean peak sitting at 1.3 micrograms/mL in TCF.
• Lastly, Procaine penicillin G was administered intramuscularly at a dose of 12 mg/kg, equivalent to 12000 IU/kg. The mean peak concentration of this compound of 0.3 microgram/mL was attained approximately 12.3 hours after administration.

Conclusion

• The researchers paid close attention to the concentration levels of the drugs because they were interested in the minimum inhibitory concentration (MIC). The MIC is an important measure of the potency of a drug; it represents the lowest concentration of the drug that restricts bacterial growth.
• The MICs for all administered drugs remained above the MIC of a common bacterium – Streptococcus zooepidemicus – for their individual proposed dosing intervals: 8, 12 and 24 hours respectively for Ampicillin sodium, Pivampicillin, and Procaine penicillin G.
• This means the chosen dosages and methods of administration were efficacious in maintaining drug levels at a point potent enough to restrict bacterial growth in the ponies’ tissues for the mentioned time intervals, demonstrating their therapeutic potential for veterinary use.