International Screening Limits-Plasma

International Screening Limits-Plasma
Definition and Recommendations for their Application in the Control of
Therapeutic Substances

Substances prohibited in racing are defined in Clause 10 of Article 6A of the International Agreement on Breeding, Racing and Wagering; accordingly therapeutic substances used for the treatment of racehorses are covered within this definition and prohibited by the rules of racing at all concentrations. In order for laboratories to report the presence of certain therapeutic substances in a consistent manner, International Screening Limits (ISLs) have been agreed for these substances.

The ISL is the urine or plasma concentration adopted for the screening of a specified therapeutic prohibited substance; it is derived from administration studies followed by a risk analysis consisting of two components: a risk assessment (evaluation of the effect of the substance and factors related to its control) and a risk management (decision step for harmonisation).  ISLs are harmonised detection limits agreed following input by international consensus and are conveyed by instruction from racing authorities to their laboratories.  The ISLs are simply the detection limits to be used by the laboratories when screening for certain therapeutic substances as instructed by the authorities; they are not international thresholds.  When the screening procedure indicates the ISL, in either urine or plasma, has been exceeded, all that is required is qualitative confirmatory analysis (usually by mass spectrometry) to confirm the presence or absence of the prohibited substance. Quantification is not required.

International Screening Limits and signatory countries

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Therapeutic Substance:
International Screening Limits - March 2016
Substance International Screening Limit
(nanograms per millilitre in plasma)
Acepromazine 0.02
Butorphanol 0.01
Carprofen 100
Dembrexine 5
Detomidine 0.02 *a
Flunixin 1
Furosemide 0.1
Lidocaine 0.05
Meclofenamic Acid 5
Mepivacaine 0.05
N-Butylscopolammonium 0.05
Phenylbutazone 100
*a Controlled by 3'-hydroxydetomidine