Data previously presented at the American College of Veterinary Anesthesiologists Scientific Meeting, New Orleans, LA, USA (2001) and at the Eighth World Congress of Veterinary Anesthesia, Knoxville, TN, USA (2003).
Relationship between plasma concentrations and analgesia after intravenous fentanyl and disposition after other routes of administration in cats1
Article first published online: 18 FEB 2005
Journal of Veterinary Pharmacology and Therapeutics
Volume 28, Issue 1, pages 87–93, February 2005
How to Cite
ROBERTSON, S. A., TAYLOR, P. M., SEAR, J. W. and KEUHNEL, G. (2005), Relationship between plasma concentrations and analgesia after intravenous fentanyl and disposition after other routes of administration in cats. Journal of Veterinary Pharmacology and Therapeutics, 28: 87–93. doi: 10.1111/j.1365-2885.2004.00628.x
- Issue published online: 18 FEB 2005
- Article first published online: 18 FEB 2005
- (Paper received 2 December 2003; accepted for publication 10 September 2004)
Data allowing rational use of analgesics in cats are limited. Pharmacokinetics and pharmacodynamics of fentanyl were studied in cats. Plasma fentanyl concentrations were measured using radioimmunoassay in a crossover study in six cats after 10 μg/kg (i.v.) or by application of fentanyl in pluronic lecithin organogel (PLO) to the inner ear pinna. On a separate occasion thermal thresholds were measured after i.v. fentanyl (10 μg/kg) or saline. Plasma fentanyl concentrations reached 4.7–8.31 ng/mL 2 min after i.v. administration and were undetectable after 95 min. Fentanyl was not detected in plasma at any time after PLO use. Thermal thresholds did not change following saline administration but were increased above baseline from 5 to 110 min after i.v. fentanyl. In this model a plasma concentration of >1.07 ng/mL was required to provide analgesia. Plasma concentrations were measured in additional cats after intranasal or oral dosing (2 μg/kg) and after 30 μg/kg in PLO gel. After oral and nasal dosing, Cmax values were 0.96 and 1.48 ng/mL at 5 and 2 min, respectively. Plasma fentanyl was not detected after application of the higher dose of fentanyl in PLO.