Disposition and Analgesic Effects of Fentanyl in White Cockatoos (Cacatua alba)
2003
Hoppes, Sharman | Flammer, Keven | Hoersch, Karen | Papich, Mark | Paul-Murphy, Joanne
Fentanyl is a mu opioid agonist with 80––100 times the analgesic potency of morphine. Fentanyl is used in several mammalian species for relief of severe pain, but its use has not been investigated in psittacine birds. To determine the pharmacologic disposition of fentanyl in healthy white cockatoos (Cacatua alba), we measured fentanyl plasma concentrations in sequentially collected samples after administration of fentanyl at 0.01 or 0.02 mg/kg IM. To investigate the analgesic effects of fentanyl in conscious cockatoos, we compared the change in pre- and posttreatment levels of electrical and thermal noxious stimuli necessary to elicit a withdrawal response in birds administered fentanyl at 2 different doses (0.02 mg/kg IM or 0.2 mg/kg SC) and those given saline. Fentanyl was rapidly absorbed and plasma concentrations declined with an elimination half-life of 1.2––1.4 hours. Plasma concentrations considered to be analgesic in humans were maintained for at least 2 hours with the 0.02 mg/kg dose. However, no significant difference was found in analgesic response between birds given saline and those given fentanyl at 0.02 mg/kg IM. Although the 0.2 mg/kg SC dose provided significant analgesia in some birds, fentanyl at this dose is not recommended as a routine analgesic agent because a large volume of drug must be injected and this dose causes hyperactivity in some birds.
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