Plasma disposition of gabapentin after the intragastric administration of escalating doses to adult horses.
Authors: Gold Jenifer R, Grubb Tamara L, Green Stephen, Cox Sherry, Villarino Nicolas F
Journal: Journal of veterinary internal medicine
Summary
# Editorial Summary: Gabapentin Pharmacokinetics in Horses Gabapentin is commonly used for analgesia in equine practice, yet its behaviour at higher doses remained poorly understood—human data suggested non-proportional pharmacokinetics, but no equine studies had examined doses above 20 mg/kg or escalating regimens. Gold and colleagues administered gabapentin via nasogastric tube to nine healthy horses across a wide dosage range (10–160 mg/kg) and tracked plasma concentrations over 64 hours using validated chromatographic methods to determine whether the drug followed proportional or non-proportional kinetics. Whilst plasma gabapentin concentrations did increase with higher doses, the relationship was non-linear: the area under the plasma concentration curve and peak concentrations did not rise proportionally to dose increments at higher dosages. This non-proportional behaviour mirrors findings in humans and has important implications for practitioners: doubling or tripling the dose will not achieve proportional increases in therapeutic plasma levels, which may explain inconsistent analgesic responses and suggests current high-dose gabapentin protocols (particularly ≥20 mg/kg) may require re-evaluation for efficacy. Understanding this pharmacokinetic ceiling may help guide more rational dosing strategies and inform discussion of gabapentin's place in equine pain management protocols alongside other analgesics.
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Practical Takeaways
- •Doubling the gabapentin dose in horses does not reliably double pain relief—expect non-proportional increases in drug exposure at doses ≥20 mg/kg, which may limit effectiveness of dose escalation for pain management
- •When considering gabapentin for analgesia in horses, be aware that doses above 20 mg/kg may not provide the expected benefit relative to the increase in dose, potentially informing treatment decisions and cost-benefit analysis
- •This research supports the need for individualized dose titration and monitoring of gabapentin efficacy in horses rather than simply increasing doses linearly
Key Findings
- •Gabapentin plasma concentration increased with dose increments from 10 to 160 mg/kg in horses administered nasogastrically
- •Area under the concentration curve and maximal plasma concentration did not increase proportionally relative to dose in horses at dosages ≥20 mg/kg
- •Non-proportional pharmacokinetics of gabapentin in horses may affect efficacy at higher dosages compared to expectations based on dose escalation