Pharmacokinetics of Oral Gabapentin in Goats: Insights from RP-HPLC Analysis

There is shifting public perception of animal welfare that has resulted in the increased demand for establishing pain management strategies in livestock, with gabapentin (GABA) often utilized in practice to mitigate neuropathic pain. However, there is little pharmacokinetic information regarding its use in goats. A joint study conducted by the College of Veterinary Medicine of Midwestern University (Glendale, Arizona), the University of California Davis School of Veterinary Medicine (Davis, California) and the College of Veterinary Medicine of the University of Tennessee (Knoxville, Tennessee) set out to describe the pharmacokinetics of oral GABA in goats given as a single dose (SD) and multidose (MD) regimen, as well as to document any adverse effects after administration.Plasma samples were collected and analyzed via reversed-phase high-performance liquid chromatography (RP-HPLC). A paper based on their research was published in The Journal of Veterinary Pharmacology and Therapeutics (1).

A positive change in public perception regarding animal welfare has caused a reassessment of pain management strategies used in livestock animals (2). As goats have become more popular in the United States as pets and companion animals, the need for easily administered treatments for their chronic painful conditions has increased (3).

Pathologic pain can be caused by tissue or nerve damage, or inflammation (4). While inflammatory pain will respond to non-steroidal anti-inflammatories and opioids, neuropathic pain does not (4,5), which led the researchers to see a need, therefore, for the identification of new treatments for use in goats to help treat chronic and neuropathic pain, as well as treatments that can be utilized in multi-modal approaches to pain management (1).

The neurotransmitter ɣ-aminobutyric acid GABA, an effective analgesic for inflammatory and chronic pain of a neuropathic origin, is not labeled for use in goats but is often prescribed as an extra-label treatment for chronic pain (4,6,7). The researchers report that there is limited scientific information regarding pharmacokinetics in goats; thus, current dosing recommendations in goats are extrapolated from other species (1).

GABA dosing is usually recommended at 10–20 mg/kg every 8–24 h in horses, dogs, and cats (8–10). In ruminant beef calves, a single oral dose of GABA alone (10 mg/kg), or co-administered (15 mg/kg) with 0.5 mg/kg meloxicam orally, reaches minimum therapeutic plasma concentrations (2 μg/mL) reported for humans for up to 15 h (4,11). A recent study in goats, evaluating a single 15 mg/kg oral dose of GABA, revealed that maximum plasma concentrations in four out of six animals were below minimum therapeutic concentrations recognized for humans (11,12). It is important to note that the minimally effective therapeutic concentration for cattle or goats has not been determined (4,12).

In practice, GABA is used to treat chronic pain and is prescribed in multiple doses over a prolonged period. While the pharmacokinetics of a single oral dose have been described in beef calves, dairy cows, and goats (4,5,12), there is no data on oral multi-dosage administration in goats. Furthermore, it takes a few weeks for GABA to reach full effect in the treatment of neuropathic pain in humans, which, in the researchers’ mind, highlights the need to study multi-dose administration in goats (13).

In this study, the pharmacokinetics of GABA in six adult, non-lactating, female Alpine and Saanen goats were investigated after SD and MD administration at 15 mg/kg. Plasma concentrations after analysis with RP-HPLC appeared like those described for calves, although elimination and time to maximum concentration appear to be shorter. MD administration revealed accumulation that extended elimination half-life and maximum plasma concentrations (1)

The researchers stress that clinicians should be aware of the potential for increased accumulation ratio with the administration of multiple doses, and future directions could evaluate the co-administration of GABA with nonsteroidal anti-inflammatory drugs (NSAIDs) as well as establish effective target concentrations for goats (1).

References

1. Ziegler, J. C.; Heller, M.; Cox, S. et al. Pharmacokinetics of Single Dose and Multidose Oral Gabapentin in Goats (Capra aegagrus hircus). J. Vet. Pharmacol. Ther. 2025.DOI: 10.1111/jvp.70006

2. Alonso, M. E.; González-Montaña, J. R.; Lomillos, J. M. Consumers' Concerns and Perceptions of Farm Animal Welfare. Animals (Basel) 2020, 10 (3), 385. DOI: 10.3390/ani10030385

3. Chew on This: Goats as Pets. Texas A&M University Veterinary Medicine & Biomedical Sciences: News & Publications 2020. https://vetmed.tamu.edu/news/pet-talk/chew-on-this-goats-as-pets/ (accessed 2025-06-12)

4. Coetzee, J. F.; Mosher, R. A.; Kohake, L. E. et al. Pharmacokinetics of Oral Gabapentin Alone or Co-Administered with Meloxicam in Ruminant Beef Calves. Vet. J. 2011, 190 (1), 98-102. DOI: 10.1016/j.tvjl.2010.08.008

5. Malreddy, P. R.; Coetzee, J. F.; Kukanich, B. et al. Pharmacokinetics and Milk Secretion of Gabapentin and Meloxicam Co-Administered Orally in Holstein-Friesian Cows. J. Vet. Pharmacol. Ther. 2013, 36 (1), 14-20. DOI: 10.1111/j.1365-2885.2012.01384.x

6. Coetzee, J. F. A Review of Analgesic Compounds Used in Food Animals in the United States. Vet. Clin. North Am. Food Anim. Pract. 2013, 29 (1), 11-28. DOI: 10.1016/j.cvfa.2012.11.008

7. Hurley, R. W.; Chatterjea, D.; Rose Feng, M. et al. Gabapentin and Pregabalin Can Interact Synergistically with Naproxen to Produce Antihyperalgesia. Anesthesiology 2002, 97 (5), 1263-1273. DOI: 10.1097/00000542-200211000-00033

8. Adrian, D.; Papich, M. G.; Baynes, R. et al. The Pharmacokinetics of Gabapentin in Cats. J. Vet. Intern. Med. 2018, 32 (6),1996-2002. DOI: 10.1111/jvim.15313

9. Gold, J. R.; Grubb, T. L.; Cox, S. et al. Pharmacokinetics and Pharmacodynamics of Repeat Dosing of Gabapentin in Adult Horses. J. Vet. Intern. Med.2022,36 (2), 792-797. DOI: 10.1111/jvim.16386

10. Kukanich, B.; Cohen RL. Pharmacokinetics of Oral Gabapentin in Greyhound Dogs. Vet. J. 2011, 187 (1), 133-135. DOI: 10.1016/j.tvjl.2009.09.022

11. Sivenius, J.; Kälviäinen, R.; Ylinen, A. et al. Double-Blind Study of Gabapentin in the Treatment of Partial Seizures. Epilepsia 1991, 32 (4), 539-542. DOI: 10.1111/j.1528-1157.1991.tb04689.x

12. Kleinhenz, M. D.; Davis, D.; Weeder, M. M. et al. Pharmacokinetic Report: Pharmacokinetics of a Single Oral Dose of Gabapentin in Goats (Capra hircus). J. Vet. Pharmacol. Ther. 2024, 47 (4), 294-299. DOI: 10.1111/jvp.13436

13. Chincholkar M. Gabapentinoids: Pharmacokinetics, Pharmacodynamics and Considerations for Clinical Practice. Br. J. Pain 2020, 14 (2), 104-114. DOI: 10.1177/2049463720912496