Pharmacokinetic Properties of a Single Administration of Oral Gabapentin in the Great Horned Owl (Bubo virginianus)
Persistent pain associated with neuropathic pain in raptor patients offers no advantage at preserving life and is often refractory to commonly utilized analgesics. Doses of common analgesics are often extrapolated from mammalian species or pharmacology studies from other avian species. The published pharmacokinetic and pharmacodynamic properties of analgesics vary considerably across avian species. Therefore, extrapolating clinical doses and dosing intervals from one species to another may be either ineffective or harmful.
Gabapentin—1-(aminomethyl) cyclohexane acetic acid—is a gamma-aminobutyric acid (GABA) analogue shown to be efficacious for neuropathic pain control in humans.1 Plasma gabapentin concentrations greater than 2 µg/ml are considered effective in treating epilepsy in humans and are suggested to provide analgesia for neuropathic pain.2 This study investigated the pharmacokinetics of a single oral (PO) dose of gabapentin suspension (11 mg/kg) in great horned owls (Bubo virginianus). Plasma gabapentin concentrations were determined in six healthy great horned owls over a 48-h period using high-performance liquid chromatography (HPLC) with mass spectrometric detection. Plasma gabapentin concentrations were estimated by a non-compartmental pharmacokinetic analysis. The harmonic mean (± standard deviation) maximum concentration (Cmax), time to maximum concentration (Tmax), and elimination half-life (tv2λZ) for gabapentin were 6.17±0.83 µg/ml, 51.43±5.66 min, and 264.60±69.35 min, respectively. Plasma gabapentin concentrations were maintained above 2 µg/ml for 528 min (8.8 h), suggesting that gabapentin administered at 11 mg/kg orally every 8 h may be appropriate for neuropathic pain control in great horned owls.
This research was generously supported by Harrison’s Bird Food Incorporated. The authors acknowledge the Iowa State Wildlife Care Clinic staff for all their husbandry efforts.
1. Cheng JK, Chiou LC. Mechanisms of the antinociceptive action of gabapentin. J Pharmacol Sci. 2006;100:471–486.
2. Sivenius J, Kälviäinen R, Ylinen A, Riekkinen P. Double-blind study of gabapentin in the treatment of partial seizures. Epilepsia. 1991;32:539–542.