Pharmacokinetics of gabapentin in horses

Neuropathic Pain Management in Chronic Laminitis

“…In the meantime two studies have been conducted in horses investigating the drug's pharmacokinetic properties as well as behavioral and cardiovascular parameters after IV and PO administration. 126,127 After IV (over 30 min) and PO administration of gabapentin (20 mg/kg), the median elimination half-lives were 8.5 and 7.7 hrs, respectively which correspond well with data in other species. 126 After IV administration plasma gabapentin concentrations remained above the 3-4 µg/mL range for approximately 15 hrs, similar to the dose associated with significant analgesic effects in adult human volunteers.…”

“…126,127 After IV (over 30 min) and PO administration of gabapentin (20 mg/kg), the median elimination half-lives were 8.5 and 7.7 hrs, respectively which correspond well with data in other species. 126 After IV administration plasma gabapentin concentrations remained above the 3-4 µg/mL range for approximately 15 hrs, similar to the dose associated with significant analgesic effects in adult human volunteers. 128 In the horse, oral bioavailability of gabapentin is relatively poor (~ 16 %) and therefore plasma gabapentin concentrations decreased much more rapidly than after IV drug administration (i.e.…”

Effect of PO Administered Gabapentin on Chronic Lameness in Horses

“…However, instead of a fast onset of analgesia, gabapentin induced a CNS calming effect and sedation may explain the reason that the mare appeared to be more comfortable two hours after administration. One pharmacokinetic study of gabapentin in horses indicated that the drug was absorbed rapidly following a single oral dose of 5 mg/kg bwt and peak plasma concentration occurred within 1.4 hours with an elimination half-life of 3.4 hours [11]. However, a more recent pharmacokinetic study found that the bioavailability of the drug when administered orally at a dose of 20 mg/kg bwt was only 16%, suggesting a poor gastrointestinal absorption profile in horses [10].…”

“…The pharmacokinetics and behavioral effects of gabapentin in horses has been previously evaluated [10,11]. The purpose of this study is to evaluate the clinical effectiveness of gabapentin in horses with chronic lameness.…”

“…Originally labeled as an anti-epileptic in human medicine, gabapentin has been used recently for the treatment of neuropathic and postoperative pain [8,9,]. Although the exact mechanism of action is not completely understood, gabapentin is believed to inhibit neurotransmitter release within the peripheral and central nervous system through interaction with the α 2 δ subunit of voltagegated calcium channels [10,11]. In humans, gabapentin is reported to be relatively safe with side effects reported to include somnolence, dizziness, sedation, and ataxia [12,13].…”