A pilot study of transdermal gabapentin in cats

Abstract

Background: Clinical use of gabapentin has increased; transdermal delivery in cats is incompletely studied.Objective: To evaluate if gabapentin permeates feline skin in vitro and in vivo and to determine if pain scores improve after administration. Animals: In vitro: cadaver skin from 6 cats; phase 1: 8 young, healthy client-owned cats; phase 2: 15 client-owned geriatric cats.Methods: In vitro, gabapentin applied every q12h to ear or cervical skin in diffusion cells. Samples collected at 0, 2, 4, 12, and 24 hours after application. Phase 1: Cats assigned to 1 of 4 groups: 5 mg/kg or 10 mg/kg applied q8h for 5 days to either ear or cervical skin. Serum samples collected predose, and after 1 and 5 days. Phase 2: 10 mg/kg applied q8h for 5 days. Two validated pain scores recorded predose, and after days 1, 5, and 8. Serum samples collected predose, and after days 1 and 5. Samples were frozen at À80 C for concentration analysis utilizing a validated highperformance liquid chromatography mass-spectrometry method.Results: Gabapentin was identified in all samples. Significant differences in gabapentin concentrations were observed from day 1 to day 5 (P < .02) and in pain scores from predose to day 5 (P < .05) and day 1 to day 5 (P < .05). No differences in pain scores were observed from predose to day 8 (P = .3).Conclusions and Clinical Relevance: Gabapentin in a transdermal base penetrates feline skin in vitro, is absorbed systemically in cats, and may help decrease pain scores.

Gabapentin: Clinical Use and Pharmacokinetics in Dogs, Cats, and Horses

“…In the study by Adrian et al (2018) [95], the transdermal formulation was also explored, but the drug concentrations were too low to be modelled with appropriate pharmacokinetic analysis, probably because of the poor absorption of the gabapentin preparation used [95]. Conversely, the results from the most recent study regarding transdermal gabapentin use in cats appeared to be promising and encouraged further investigations on the use of this alternative administration route [78]. Indeed, the results provided by Slovak and Costa (2021) [78], using gabapentin in a 10% or 20% Lipoderm base transdermal preparation, clearly demonstrated that this drug can permeate feline skin in vitro and can be systemically absorbed in vivo, advocating the need to deepen the knowledge on this administration route [78].…”

“…For the control of chronic osteoarthritis-related pain, gabapentin was associated with improvement in owner-identified impaired activities, but with a lack of improvement in the owners’ reported quality of life, probably due to the high incidence of sedative effects [ 40 , 78 ]. In a preliminary study on transdermal administration of gabapentin in geriatric cats, drug systemic absorption and a decrease in pain scores were observed [ 78 ]. Conversely, gabapentin administered at three different doses did not affect the thermal threshold in healthy cats and, therefore, was not able to provide thermal antinociception [ 79 ].…”

“…Conversely, the results from the most recent study regarding transdermal gabapentin use in cats appeared to be promising and encouraged further investigations on the use of this alternative administration route [ 78 ]. Indeed, the results provided by Slovak and Costa (2021) [ 78 ], using gabapentin in a 10% or 20% Lipoderm base transdermal preparation, clearly demonstrated that this drug can permeate feline skin in vitro and can be systemically absorbed in vivo, advocating the need to deepen the knowledge on this administration route [ 78 ].…”

2022 ISFM Consensus Guidelines on the Management of Acute Pain in Cats

“…161 However, another study showed that gabapentin in the proprietary base Lipoderm did result in measurable plasma concentrations. 163 The authors of the latter study caution that their investigation involved a small number of cats and, because grooming was allowed, uptake may have occurred transmucosally. More studies using different transdermal creams, concentrations, doses and dosing intervals are needed.…”