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Abstract

OBJECTIVE

To examine the pharmacokinetics and ex vivo pharmacodynamics of oral firocoxib administration in New Zealand White rabbits (Oryctolagus cuniculus).

ANIMALS

6 healthy New Zealand White rabbits.

PROCEDURES

Pharmacokinetics were determined from plasma concentrations measured via ultra performance liquid chromatography-tandem mass spectrometry after oral administration of firocoxib at a dose of 3.74 to 4.20 mg/kg. Pharmacokinetic analysis was performed using non compartmental methods. Pharmacodynamics of firocoxib were evaluated by measuring plasma concentrations of thromboxane and prostaglandin via ELISAs as surrogate markers of cyclooxygenase enzyme isoform inhibition.

RESULTS

The terminal rate constant was 0.07 hours (range, 0.05 to 0.11 h). The mean maximum concentration (Cmax) and time to Cmax were 0.16 µg/mL and 3.81 hours (range, 2.0 to 8.0 h), respectively. Mean residence time was 15.02 hours. Mean elimination half-life was 9.12 hours. For the pharmacodynamic analysis, firocoxib administration did not demonstrate a significant difference between any time point for prostaglandin E2 and only a significant difference between 24 and 48 hours for thromboxane B2.

CLINICAL RELEVANCE

Although the pharmacokinetic research supports that plasma firocoxib concentrations that would be therapeutic in dogs are achieved in rabbits, the pharmacodynamic results do not demonstrate a significant difference in levels of cyclooxygenase-2 inhibition, which indirectly reflects the anti-inflammatory effects of the drug. Further pharmacodynamic studies and multidose studies are warranted to determine the efficacy and safety of this drug in rabbits.

Open access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

This study sought to determine whether firocoxib (FIRO) or meloxicam (MEL) was effective at providing analgesia after surgical castration in goats.

ANIMALS

18 intact male crossbred goats (6 to 8 months old) were enrolled with a mean weight of 32.6 (± 2.9) kg.

METHODS

Surgical castration was done under injectable anesthesia by a licensed veterinarian. Twelve bucks were surgically castrated and given either FIRO (n = 6) or MEL (n = 6). Six bucks served as controls (CNTLs) and were not castrated. Outcome measurements included visual analogue scale, infrared thermography, plasma cortisol, plasma substance P, and kinetic gait analysis. All outcome measurements were obtained at –24, 4, 8, 24, 48, and 72 hours.

RESULTS

All 3 treatments were significantly different from each other at the 24- and 48-hour time points, with MEL animals having lower visual analogue scale scores when compared to FIRO animals; CNTL animals exhibited the lowest plasma cortisol levels (3.19 ng/mL; 95% CI, –1.21 to 7.59 ng/mL) followed by FIRO (7.45 ng/mL; 95% CI, 3.10 to 11.80 ng/mL) and MEL (10.24 ng/mL; 95% CI, 5.87 to 14.60 ng/mL). FIRO had an average mean decrease in gait velocity change (–54.17 cm/s; 95% CI, –92.99 to –15.35 cm/s), while MEL had an increase in gait velocity when compared to baseline values (14.54 cm/s; 95% CI, –24.27 to 53.36 cm/s). Control animals had an average mean of –3.06 cm/s (95% CI, –41.88 to 35.75 cm/s).

CLINICAL RELEVANCE

Results from this study showed that there were some analgesic effects from administering MEL when compared to bucks that received a placebo treatment (CNTL).

Open access
in Journal of the American Veterinary Medical Association