(E43) Pharmacokinetics of S-Adenosylmethionine in Horses Using a Crossover Study Design with Three Dosing Regimens

Abstract:

Background: Supplementation of s-adenosylmethionine (SAMe) can be useful in supporting liver health through augmentation of glutathione levels across many species. The pharmacokinetics of SAMe have yet to be reported in horses.
Hypothesis/

Objectives: The objective of this study was to determine the pharmacokinetics of a proprietary formulation of SAMe (NMXSS75A; Nutramax Laboratories, Inc) in horses. The hypothesis was that plasma concentrations would be dose-dependent and not affected by a small concentrate meal.
Animals: Six healthy adult mares from a research herd.

Methods: Crossover study design with a 7-day washout period using three dosing regimens: S10 (10 g SAMe), S10 + FEED (10 g SAMe + 0.5 lb concentrate), and S5 (5 g SAMe). The SAMe formulation was administered via nasogastric intubation. Blood samples were collected within 1 hour pre-dose and at 0.5, 1, 2, 4, 6, 8, and 24 hours post-dose for each regimen.

Results: The maximum concentration (Cmax; p = 0.017), 24-hour area under the curve (AUC; p = 0.015) and time to maximum concentration (Tmax; p < 0.001) differed among groups. Cmax (p = 0.017) and AUC (p < 0.001) were higher for S10 (Cmax: 1069 ± 379 ng/mL; AUC: 3247 ± 965 ng*hr/mL) compared to S5 (619 ± 253 ng/mL; 1460 ± 553 ng*hr/mL). AUC (p < 0.001) was greater for S10 + FEED (2748 ± 687 ng*hr/mL) compared to S5. The Tmax (p = 0.014) was prolonged for S10 + FEED (1.83 ± 0.41 hr) compared to S5 (0.92 ± 0.20 hr).
Conclusions and Clinical Importance: Plasma concentrations of SAMe were dose-dependent and minimally affected by a small concentrate meal. This study provides plasma pharmacokinetic data for SAMe in horses to help guide its use in clinical practice.