Control of the misuse of bromide in horses

Abstract

Bromide is a sedative hypnotic. Due to its potential use as a sedative or calmative agent in competition horses, a method to control bromide is needed. Colorimetric method had been employed in the authors' laboratory from 2003 for the semi-quantification of bromide in equine plasma samples. However, the method was found to be highly susceptible to matrix interference, and was replaced in 2008 with a more reliable inductively coupled plasma-mass spectrometry (ICP/MS) method. Equine plasma was protein-precipitated using trichloroacetic acid, diluted with nitric acid, and then submitted directly to ICP/MS analysis. Since bromide is naturally occurring in equine plasma, a threshold is necessary to control its misuse in horses. Based on population studies (n = 325), a threshold of 90 µg/mL was proposed (with a risk factor of less than 1 in 10 000). Using the ICP/MS screening method, equine plasma samples with bromide greater than 85 µg/mL would be further quantified using the more accurate ICP/MS standard addition method. Confirmation of bromide was achieved by gas chromatography-mass spectrometry (GC-MS), with the bromide detected as its pentafluorobenzyl derivative. A sample is considered positive if its plasma bromide concentration exceeds the threshold (90 µg/mL) plus the measurement uncertainty of the quantification method (8 µg/mL at 99% 1-tailed confidence level) and its presence is confirmed using the GC-MS method. Following oral administration of potassium bromide (60 g each) to two geldings, plasma bromide levels peaked after approximately 2 hours at about 300 µg/mL, and then remained above the threshold for 8 and 13 days respectively.

Controlling the misuse of cobalt in horses

“…Besides its high sensitivity and fast turnaround time, another major advantage of using ICP‐MS to quantify total cobalt in biological samples is the simple sample preparation required. Blood and urine can often be analyzed directly after dilution with acid . This paper describes ICP‐MS methods for the quantification of total cobalt in equine plasma and urine.…”

“…Blood and urine can often be analyzed directly after dilution with acid. [18,19] This paper describes ICP-MS methods for the quantification of total cobalt in equine plasma and urine. Equine plasma was first protein-precipitated.…”

Doping control analysis of lithium in horse urine and plasma by inductively coupled plasma mass spectrometry

“…The quantification methods reported herein for urine and plasma are based on methods reported by the author's laboratory . Scandium was chosen as the internal standard for urine as it is one of the elements that has negligible natural amount in urine and has molecular mass of 45 Da, closest to lithium of 7 Da.…”

“…The quantification methods reported herein for urine and plasma are based on methods reported by the author's laboratory. [14][15][16] Scandium was chosen as the internal standard for urine as it is one of the elements that has negligible natural amount in urine and has molecular mass of 45 Da, closest to lithium of 7 Da. For the plasma method, a different internal standard, germanium, was chosen as scandium spiked in plasma showed sample-tosample variations, probably due to the binding of scandium (as Sc 3+ ) to plasma proteins.…”

Pharmacokinetics of bromide in adult sheep following oral and intravenous administration

“…In Australia, KBr is registered in dogs for the treatment of idiopathic epilepsy and it is being increasingly used worldwide for seizure therapy as it is associated with fewer side‐effects than phenobarbitone . It is also used extensively off‐label by horse owners as a calmative for nervous horses; however, to date little research has been undertaken as to its efficacy and appropriate application …”