Pharmacokinetics of cisapride in horses after intravenous and rectal administration.

This research investigated the effectiveness of administering the drug cisapride to horses via intravenous (IV) and rectal methods. The study found that the drug was absorbed at a high concentration when administered intravenously, but was barely absorbed when administered rectally.

Research Methodology

• The study involved 5 healthy adult mares ranging between 380 to 610 kg in weight.
• Each horse was given a dose of Cisapride intravenously, at a rate of 0.1 mg/kg of body weight. The horses were then allowed a 1-week washout period to reset their systems.
• After the washout period, Cisapride was administered rectally at a dosage of 1 mg/kg. The rectal administration was done by mixing crushed tablets with propylene glycol and introducing the mixture into the rectum.
• After each drug administration, blood samples were taken from each horse to evaluate how well the drug was absorbed into the system. The plasma from the blood was analyzed using high-performance liquid chromatography to determine the concentration profiles.

Research Findings

• The IV administration of Cisapride resulted in a peak plasma concentration of 221.4 ng/ml. The average half-life of the drug in the system was found to be 1.9 hours.
• However, the rectal administration of Cisapride yielded negligible absorption. Cisapride was only detected in the plasma of 3 out of the 5 horses, with an average systemic availability of just 1.23%. The mean maximal plasma concentration observed after rectal administration was 13.5 ng/ml.

Conclusion

• Based on the study, the researchers determined that Cisapride is not suitable for rectal administration in horses due to its poor absorption rate. The drug concentration in the plasma was substantially higher when administered intravenously compared to rectal administration.
• The high plasma concentration remained for about 2 hours after IV administration, while rectal administration showed insignificant absorption and very low systemic availability.
• Given these results, the research concluded that Cisapride administered rectally using propylene glycol is not clinically beneficial in horses.