Pilot study to quantify the time to clear dexamethasone from plasma and urine of adult horses following a single nebulisation

Abstract

Objective To quantify the time to clear dexamethasone from plasma and urine of horses following a single nebulisation.Design Experimental using six Standardbred mares.Methods Dexamethasone sodium phosphate (0.04 mg/kg) diluted in 0.9% sodium chloride was administered as an aerosol using a Flexineb E2® nebuliser. Blood samples (0, 2, 4, 6, 8, 10, 12, 24, 32, 48, 72 and 96 h) and urine samples (0, 1, 4, 8, 24, 32, 48, 72 and 96 h) were collected for analysis using liquid chromatography mass spectrometry.Results Maximum plasma concentrations (t max ) were reached by the earliest detection point (2 h) after nebulisation (0.6--1.8 ng/mL), but was no longer detectable at 48 h. However, in one horse 0.1 ng/mL was found at 96 h after three consecutive readings of 0 ng/mL. The t max in urine was reached by the earliest collection point (1 h) after nebulisation (3.2-23.8 ng/mL), but was no longer present in urine at 72 h in five horses, while detectable levels (0.1 ng/mL) were still present at 96 h in one horse.Conclusions A single dose of 0.04 mg/kg of DSP administered as an aerosol through a FlexinebE2® mask was no longer detectable in blood at 48 h in six horses tested, but one horse returned a reading of 0.1 ng/mL at 96 h after having no detectable levels. Dexamethasone was not detectable in urine at 72 h in five horses but was detectable at a low concentration (0.1 ng/mL) at 96 h in one horse.

Doping detection in animals: A review of analytical methodologies published from 1990 to 2019

“…The abuse of these substances has been a constant challenge for anti‐doping agencies, so the control of corticosteroids is absolutely necessary, not only to ensure the existence of clean and drug‐free sports but also to protect the athletes from masked injuries and additional effort caused by the concealing of pain, both in human and in animals. Owing to the recognized side effects of these drugs, it is not surprising that 19 publications about the development of analytical methods specifically to detect corticosteroids in samples from racing horses were found since 1990 11,13,227–243 . In a review of clinical use and characteristics of the corticosteroids, several complications were associated with their chronic abuse in horses, namely, increased rate of joint breakdown, septic arthritis, degenerative joint disease, suppression of the hypothalamic–pituitary adrenal system, increased susceptibility to infection, and laminitis, a painful and potentially crippling disease resulting from the inflammation of the lamina of the hoof 244 …”

“…Owing to the recognized side effects of these drugs, it is not surprising that 19 publications about the development of analytical methods specifically to detect corticosteroids in samples from racing horses were found since 1990. 11,13,[227][228][229][230][231][232][233][234][235][236][237][238][239][240][241][242][243] In a review of clinical use and characteristics of the corticosteroids, several complications were associated with their chronic abuse in horses, namely, increased rate of joint breakdown, septic arthritis, degenerative joint disease, suppression of the hypothalamic-pituitary adrenal system, increased susceptibility to infection, and laminitis, a painful and potentially crippling disease resulting from the inflammation of the lamina of the hoof. 244 Cortisol, also known as hydrocortisone, is considered the precursor of all glucocorticoid drugs.…”

Glucocorticoid treatment in horses with asthma: A narrative review

“…Alternatively, it could be explained by a higher delivery to the gastrointestinal tract in asthmatic animals because of greater airway obstruction, cough, or mucus accumulation impairing penetration in lower airways. The plasma and urinary clearance of nebulized dexamethasone has been described 65 …”

In this issue ‐ May 2019: West Nile virus in horses · Treating horses with dexamethasone via nebulisation · Animal hoarding in NSW · Dangers of powdered washing soda for emesis in dogs · Pneumocystis in a dog following toceranib phosphate · Oxalate nephrosis in koalas

“…2 Although dexamethasone is effective, it has been associated with adverse side effects and there is also a concern that it may be identified as part of drug testing urine and blood samples in equine sports. 2 Although dexamethasone is effective, it has been associated with adverse side effects and there is also a concern that it may be identified as part of drug testing urine and blood samples in equine sports.…”

“…A pilot study using six Standardbred mares looks at the value of using nebulisation of dexamethasone for treatment of horses with equine asthma (non-septic lower airway disease). 2 Although dexamethasone is effective, it has been associated with adverse side effects and there is also a concern that it may be identified as part of drug testing urine and blood samples in equine sports. The study used a single dose of dexamethasone given by nebulisation on the grounds that it may give an effective dose to the lungs without having major systemic effects.…”