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  • Author or Editor: Joanne Paul-Murphy x
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Abstract

OBJECTIVE

To evaluate the pharmacokinetics of hydromorphone hydrochloride after IM and IV administration to orange-winged Amazon parrots (Amazona amazonica).

ANIMALS

8 orange-winged Amazon parrots (4 males and 4 females).

PROCEDURES

Hydromorphone (1 mg/kg) was administered once IM. Blood samples were collected 5 minutes and 0.5, 1.5, 2, 3, 6, and 9 hours after drug administration. Plasma hydromorphone concentrations were determined with liquid chromatography-tandem mass spectrometry, and pharmacokinetic parameters were calculated with a compartmental model. The experiment was repeated 1 month later with the same dose of hydromorphone administered IV.

RESULTS

Plasma hydromorphone concentrations were > 1 ng/mL for 6 hours in 8 of 8 and 6 of 7 parrots after IM and IV injection, respectively. After IM administration, mean bioavailability was 97.6%, and mean maximum plasma concentration was 179.1 ng/mL 17 minutes after injection. Mean volume of distribution and plasma drug clearance were 4.24 L/kg and 64.2 mL/min/kg, respectively, after IV administration. Mean elimination half-lives were 1.74 and 1.45 hours after IM and IV administration, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE

Hydromorphone hydrochloride had high bioavailability and rapid elimination after IM administration, with rapid plasma clearance and a large volume of distribution after IV administration in orange-winged Amazon parrots. Drug elimination half-lives were short. Further pharmacokinetic studies of hydromorphone and its metabolites, including investigation of multiple doses, different routes of administration, and sustained-release formulations, are recommended.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To identify an oral dose of grapiprant for red-tailed hawks (RTHAs; Buteo jamaicensis) that would achieve a plasma concentration > 164 ng/mL, which is considered therapeutic for dogs with osteoarthritis.

ANIMALS

6 healthy adult RTHAs.

PROCEDURES

A preliminary study, in which grapiprant (4 mg/kg [n = 2], 11 mg/kg [2], or 45 mg/kg [2]) was delivered into the crop of RTHAs from which food had been withheld for 24 hours, was performed to obtained pharmacokinetic data for use with modeling software to simulate results for grapiprant doses of 20, 25, 30, 35, and 40 mg/kg. Simulation results directed our selection of the grapiprant dose administered to the RTHAs in a single-dose study. Plasma grapiprant concentration, body weight, and gastrointestinal signs of RTHAs were monitored.

RESULTS

On the basis of results from the preliminary study and simulations, a grapiprant dose of 30 mg/kg was used in the single-dose study. The geometric mean maximum observed plasma concentration of grapiprant was 3,184 ng/mL, time to maximum plasma grapiprant concentration was 2.0 hours, and the harmonic mean terminal half-life was 17.1 hours. No substantial adverse effects were observed.

CONCLUSIONS AND CLINICAL RELEVANCE

Although the single dose of grapiprant (30 mg/kg) delivered into the crop achieved plasma concentrations > 164 ng/mL in the RTHAs, it was unknown whether this concentration would be therapeutic for birds. Further research that incorporates multidose assessments, safety monitoring, and pharmacodynamic data collection is warranted on the use of grapiprant in RTHAs from which food was withheld versus not withheld.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To determine the pharmacokinetics of amantadine after oral administration of single and multiple doses to orange-winged Amazon parrots (Amazona amazonica).

ANIMALS

12 adult orange-winged Amazon parrots (6 males and 6 females).

PROCEDURES

A single dose of amantadine was orally administered to 6 birds at 5 mg/kg (n = 2), 10 mg/kg (2), and 20 mg/kg (2) in a preliminary trial. On the basis of the results, a single dose of amantadine (10 mg/kg, PO) was administered to 6 other birds. Two months later, multiple doses of amantadine (5 mg/kg, PO, q 24 h for 7 days) were administered to 8 birds. Heart rate, respiratory rate, behavior, and urofeces were monitored. Plasma concentrations of amantadine were measured via tandem liquid chromatography–mass spectrometry. Pharmacokinetic parameter estimates were determined via noncompartmental analysis.

RESULTS

Mean ± SD maximum plasma concentration, time to maximum plasma concentration, half-life, and area under the concentration-versus-time curve from the last dose to infinity were 1,174 ± 186 ng/mL, 3.8 ± 1.8 hours, 23.2 ± 2.9 hours, and 38.6 ± 7.4 μg·h/mL, respectively, after a single dose and 1,185 ± 270 ng/mL, 3.0 ± 2.4 hours, 21.5 ± 5.3 hours, and 26.3 ± 5.7 μg·h/mL, respectively, at steady state after multiple doses. No adverse effects were observed.

CONCLUSIONS AND CLINICAL RELEVANCE

Once-daily oral administration of amantadine at 5 mg/kg to orange-winged Amazon parrots maintained plasma concentrations above those considered to be therapeutic in dogs. Further studies evaluating safety and efficacy of amantadine in orange-winged Amazon parrots are warranted.

Full access
in American Journal of Veterinary Research

Abstract

OBJECTIVE To determine pharmacokinetics after oral administration of single and multiple doses and to assess the safety of zonisamide in Hispaniolan Amazon parrots (Amazona ventralis).

ANIMALS 12 adult Hispaniolan Amazon parrots.

PROCEDURES Zonisamide (30 mg/kg, PO) was administered once to 6 parrots in a single-dose trial. Six months later, a multiple-dose trial was performed in which 8 parrots received zonisamide (20 mg/kg, PO, q 12 h for 10 days) and 4 parrots served as control birds. Safety was assessed through monitoring of body weight, attitude, and urofeces and comparison of those variables and results of CBC and biochemical analyses between control and treatment groups.

RESULTS Mean ± SD maximum plasma concentration of zonisamide for the single- and multiple-dose trials was 21.19 ± 3.42 μg/mL at 4.75 hours and 25.11 ± 1.81 μg/mL at 2.25 hours after administration, respectively. Mean plasma elimination half-life for the single- and multiple-dose trials was 13.34 ± 2.10 hours and 9.76 ± 0.93 hours, respectively. Pharmacokinetic values supported accumulation in the multiple-dose trial. There were no significant differences in body weight, appearance of urofeces, or appetite between treated and control birds. Although treated birds had several significant differences in hematologic and biochemical variables, all variables remained within reference values for this species.

CONCLUSIONS AND CLINICAL RELEVANCE Twice-daily oral administration of zonisamide to Hispaniolan Amazon parrots resulted in plasma concentrations known to be therapeutic in dogs without evidence of adverse effects on body weight, attitude, and urofeces or clinically relevant changes to hematologic and biochemical variables.

Full access
in American Journal of Veterinary Research