Transdermal fentanyl combined with nonsteroidal anti-inflammatory drugs for analgesia in horses

Sara M Thomasy, N. Slovis, L. K. Maxwell, C. Kollias-Baker

Research output: Contribution to journalArticle

53 Citations (Scopus)

Abstract

This study investigated the pharmcokinetics, efficacy, and safety of the fentanyl transdermal therapeutic system (TTS) in horses in which there was an inadequate analgesic response to nonsteroidal anti-inflammatory drugs (NSAIDs) alone. Nine horses with pain that was refractory to therapeutic doses of phenylbutazone (n = 3) or flunixin meglumine (n = 6) subsequently also received between 39 and 110 μg/kg of transdermal fentanyl. Blood samples were collected at 0, 1, 2, 3, 4, 5, 6, 12, 24, 36, 48, 60, and 72 hours after patch application, and a radioimmunoassay was used to determine serum fentanyl concentrations. Pharmacokinetic values were determined by noncompartmental analysis. Physical examination findings were recorded in all horses, and pain and lameness grading systems were used to assign scores to 8 and 6 horses, respectively. All horses tolerated the administration of fentanyl TTS, in that no clinically significant adverse effects attributable to fentanyl were observed. Use of the TTS resulted in variable serum concentrations of fentanyl, with a peak serum concentration of 2.2 ± 1.1 ng/mL (mean ± SD) and a time to peak serum concentration of 26 ± 13 hours. After transdermal fentanyl administration, mean time to reach serum fentanyl concentrations consistent with analgesia in other species (1 ng/mL) was 14 hours. In addition, serum fentanyl concentrations of 1 ng/mL or greater were maintained in all but one horse for at least 18 hours. Pain scores were significantly decreased after fentanyl TTS and NSAID administration (P < .05), but lameness scores were not significantly different (P > .05). Overall, administration of fentanyl TTS had a favorable pharmacokinetic profile in horses with clinical pain, and the fentanyl TTS in combination with NSAIDs appeared to provide safe and effective analgesia in most of the horses with pain that was refractory to NSAID therapy alone.

Original languageEnglish (US)
Pages (from-to)550-554
Number of pages5
JournalJournal of Veterinary Internal Medicine
Volume18
Issue number4
DOIs
StatePublished - Jul 2004

Fingerprint

fentanyl
nonsteroidal anti-inflammatory agents
Fentanyl
analgesia
Analgesia
Horses
Anti-Inflammatory Agents
horses
blood serum
Pharmaceutical Preparations
therapeutics
pain
Cutaneous Administration
Serum
Intractable Pain
Pain
pharmacokinetics
Therapeutics
Pharmacokinetics
phenylbutazone

Keywords

  • Equine
  • Opioids
  • Pain
  • Pharmacodynamics
  • Pharmacokinetics

ASJC Scopus subject areas

  • veterinary(all)

Cite this

Transdermal fentanyl combined with nonsteroidal anti-inflammatory drugs for analgesia in horses. / Thomasy, Sara M; Slovis, N.; Maxwell, L. K.; Kollias-Baker, C.

In: Journal of Veterinary Internal Medicine, Vol. 18, No. 4, 07.2004, p. 550-554.

Research output: Contribution to journalArticle

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