Pharmacokinetics and tolerance of transdermal fentanyl administration in foals.

The research paper focuses on the study of the effects and tolerance of transdermal fentanyl administration to young foals. The results showed a variance in peak plasma concentrations after application, with no significant adverse effects noted.

Experiment Overview

• The study was a prospective look into the pharmacokinetics of fentanyl after administrating a single dose through a transdermal system (TS) on foals. The research involved six foals aged 4-8 days and weighed between 56-74 kg.
• For manageable sample collection and monitoring, a jugular catheter was implanted in the foals by the researchers. A single transdermal fentanyl system, which contains 10.2 mg of fentanyl capable of releasing the drug at a pace of 100 micrograms per hour, was administered for a total of 72 hours.
• Blood samples were collected over 90 hours for detailed fentanyl plasma analysis to track and record the pharmacokinetics of the drug. Other details such as the foals’ weight, complete blood count, and blood chemistry values were also noted before and after the study.
• The vital part of the study was to evaluate the foals’ tolerance to fentanyl and the overall safety of the procedure. This involved regular physical examinations and behavior assessments. Moreover, to clarify that there were no significant adverse effects observable.

Research Findings

• Fentanyl was detected in the foals’ system as early as 20 minutes after applying the TS. There was variability in peak plasma concentrations, ranging from 0.1-28.7 ng mL(-1), and those were reached after 14.3 +/- 7.6 hours.
• The researchers discovered that the plasma concentrations return to baseline or normal values about 12 hours post removing the FTS.
• All the foals involved in the study showed satisfactory tolerance to the application of the FTS, and no discernible adverse effects were observed.
• A slight increase in rectal temperature was noted in all the foals which went to a maximum of 39.0 degrees Celsius. However, the researchers found no correlation between the change in temperature and fentanyl plasma concentrations.
• All hematological and biochemical analyses results were within normal or reference ranges, marking no significant disturbance due to drug administration.

Conclusion

• Broadly, the study concludes that 100 micrograms per hour of fentanyl administered via an FTS does result in time-related but variable plasma concentrations in foals.
• The FTS was easy to apply and well tolerated by the young animals, demonstrating its safety and reliability as a drug administration mode. This could offer different avenues for development in veterinary pharmacokinetics and pain management strategies.