Fenylbutazon - tillåta vid tävling?

Abstract: Phenylbutazone has been discussed in the world of the equestrian sport several times and different countries have diverse opinions on its use in competitions. The progressive list that permits phenylbutazone with plasma levels up to 8 µg/ml was presented at the FEI General Assembly in November 2009. The list was voted to be accepted, but later several countries realized the consequences and after protests the list was rejected and is going to be discussed again at the FEI General Assembly 2010. In this literature study I have studied the relationship between the concentrations of phenylbutazone in plasma and the effects on lameness. The purpose was to establish whether the limit of 8 µg/ml phenylbutazone in plasma affects the equestrian sport. In addition I have also studied the adverse reactions of phenylbutazone. Phenylbutazone was introduced in veterinary medicine in the 1950s and many scientific studies have been performed. The duration of phenylbutazone is long and may depend on the accumulation in inflamed tissue. The dose 2 mg/kg gives maximum effect and higher doses prolong the duration. Studies have proved that concentrations < 2 µg/ml will reduce mild lameness and that concentrations < 8 µg/ml will reduce severe lameness. Common adverse reactions of phenylbutazone are gastric ulcers, renal papillary necrosis and hematological disturbances. Other unwanted effects are increased heart rate and right atrial pressure and also suppression of proteoglycan synthesis in articular cartilage. Adverse reactions are most common in horses treated with phenylbutazone in doses higher than recommended and administrated for longer periods than recommended, but there is also an individually sensitivity. In addition, phenylbutazone also seems to have more adverse reactions than other NSAIDs. Permitting therapeutic concentration of phenylbutazone in competitions will damage the reliability of the sport and both horses and riders could be in risk of danger.