Serum concentrations and analgesic effects of liposome-encapsulated and standard butorphanol tartrate in parrots.
OBJECTIVE
To compare serum concentrations of liposome-encapsulated butorphanol tartrate (LEBT) and standard butorphanol tartrate (STDBT) following SC and IM administration, respectively, and to evaluate analgesic effects of LEBT and STDBT after parenteral administration to Hispaniolan parrots.


METHODS
11 adult Hispaniolan parrots.


METHODS
The ability of LEBT to prolong the duration of analgesia in an avian species was tested. Blood samples were collected at serial time points after SC administration of LEBT (10 mg/kg or 15 mg/kg) or IM administration of STDBT (5 mg/kg). Serum concentrations of butorphanol tartrate were determined by use of a commercial immunoassay that measured parent drug and metabolites. Analgesic efficacy was evaluated in parrots exposed to electrical and thermal stimuli. Foot withdrawal thresholds were recorded at baseline and at serial time points after LEBT (15 mg/kg), liposome vehicle, STDBT (2 mg/kg), or physiologic saline (0.9% NaCl) solution administration.


RESULTS
LEBT had a prolonged in vivo release for up to 5 days. Negligible serum butorphanol and butorphanol metabolite concentrations were obtained at 24 hours after IM administration of STDBT. Analgesic efficacy of LEBT as measured by foot withdrawal threshold to noxious thermal and electrical stimuli persisted for 3 to 5 days following SC administration of LEBT.


CONCLUSIONS
SC administration of LEBT provided analgesia and detectable serum butorphanol concentrations in Hispaniolan parrots for up to 5 days. The use of LEBT may allow for substantial improvement in long-term pain relief without subjecting birds to the stress of handling and multiple daily injections.
Sladky
Kurt K
KK
Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53705, USA.
Krugner-Higby
Lisa
L
Meek-Walker
Elizabeth
E
Heath
Timothy D
TD
Paul-Murphy
Joanne
J
D046708:Amazona / Q000097:blood*; D000698:Analgesia / Q000662:veterinary*; D000701:Analgesics, Opioid / Q000097:blood / Q000493:pharmacokinetics / Q000627:therapeutic use; D000818:Animals; D002077:Butorphanol / Q000008:administration & dosage / Q000097:blood* / Q000493:pharmacokinetics / Q000627:therapeutic use*; D002626:Chemistry, Pharmaceutical; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D008081:Liposomes / Q000008:administration & dosage*; D010146:Pain / Q000188:drug therapy*
D000701:Analgesics, Opioid; D008081:Liposomes; D002077:Butorphanol