Pharmacokinetics and physiologic effects of alprazolam after a single oral dose in healthy mares.

This research focused on studying the pharmacokinetic properties (how a drug is absorbed, distributed, metabolized, and excreted in the body) and physiological effects of a one-time oral dose of alprazolam in horses. The outcomes show that the drug was absorbed by the horses’ bodies and caused no observable adverse effects, suggesting further exploration of its safe use is needed.

Study Design

• The study involved seven healthy, fully grown female horses.
• Each horse was given a single oral dose of alprazolam (known as an anti-anxiety medicine in humans) at a dosage tailored to their body weight (0.04mg per kilogram).
• The team then sampled the horses’ blood at different times to measure the levels of alprazolam and one of its metabolites, α-hydroxyalprazolam.
• To determine these levels, the researchers used a technique called liquid chromatography/mass spectrometry, which separates the components of a substance and measures their relative concentration.

Findings

• The study’s results were analyzed using a ‘one-compartmental approach,’ which assumes the body as a single, uniform entity for drug distribution.
• Key measurements taken included the ‘maximum concentration’ (Cmax), ‘time to reach maximum concentration’ (Tmax), and total amount of drug in the body over time, also measured as ‘area under the curve’ (AUC).
• The average Cmax for alprazolam was found to be 14.76 ± 3.72 ng/mL, with an average AUC of 358.77 ± 76.26 ng·h/mL. The median Tmax (time it took to reach this concentration in blood) was 3 hours, although it varied between 1-12 hours.
• The researchers also found α-hydroxyalprazolam in every horse, yet at low levels.

Physical Examination and Adverse Effects

• To assess any side effects, repeating physical examinations and evaluation of sedation and ataxia (loss of coordination) were performed every 12 hours.
• No clinically significant adverse effects were detected, indicating that the horses tolerated the drug well.

Conclusion

• The research concluded that the alprazolam tablets taken orally were absorbed into the body of adult horses, with no significant adverse effects.
• However, it recommends further study for repeated dosing and the safety of administering alprazolam to horses.