Butazolidin

Phenylbutazone

Clinical data
Trade names	Butazolidine
ATC code	M01AA01 (WHO) M02AA01 (WHO)
Legal status
Legal status	In general: ℞ (Prescription only)
Identifiers
IUPAC name 4-Butyl-1,2-diphenyl-pyrazolidine-3,5-dione
CAS Number	50-33-9 Y
PubChem CID	4781
IUPHAR/BPS	7270
DrugBank	DB00812 Y
ChemSpider	4617 Y
UNII	GN5P7K3T8S
KEGG	D00510 Y
ChEBI	CHEBI:48574 Y
ChEMBL	CHEMBL101 Y
ECHA InfoCard	100.000.027
Chemical and physical data
Formula	C19H20N2O2
Molar mass	308.374 g/mol
3D model (JSmol)	Interactive image
SMILES O=C2N(c1ccccc1)N(C(=O)C2CCCC)c3ccccc3
InChI InChI=1S/C19H20N2O2/c1-2-3-14-17-18(22)20(15-10-6-4-7-11-15)21(19(17)23)16-12-8-5-9-13-16/h4-13,17H,2-3,14H2,1H3 Y Key:VYMDGNCVAMGZFE-UHFFFAOYSA-N Y

Phenylbutazone, often referred to as "bute," is a nonsteroidal anti-inflammatory drug (NSAID) for the short-term treatment of pain and fever in animals.

In the United States and United Kingdom it is no longer approved for human use (except for ankylosing spondylitis, because no other treatment is available), as it can cause severe adverse effects such as suppression of white blood cell production and aplastic anemia. This drug was implicated in the 2013 meat adulteration scandal. Positive phenylbutazone tests in horse meat were uncommon in the UK, however.

Phenylbutazone was originally made available for use in humans for the treatment of rheumatoid arthritis and gout in 1949. However, It is no longer approved, and therefore not marketed, for any human use in the United States. In the UK it is used to treat ankylosing spondylitis, but only when other therapies are unsuitable.

Phenylbutazone is the most commonly used NSAID for horses in the United States. It is used for the following purposes:

In the 1968 Kentucky Derby, Dancer's Image, the winner of the race, was disqualified after traces of phenylbutazone were allegedly discovered in a post-race urinalysis. Owned by prominent Massachusetts businessman Peter Fuller and ridden by jockey Bobby Ussery, Dancer's Image remains the only horse to win the Kentucky Derby and then be disqualified. Phenylbutazone was legal on most tracks around the United States in 1968, but had not yet been approved by Churchill Downs.

Controversy and speculation still surround the incident. In the weeks prior to the race, Peter Fuller had given previous winnings to Coretta Scott King, the widow of slain civil rights activist Martin Luther King Jr., which brought both praise and criticism. The previous year, King held a sit-in against housing discrimination which disrupted Derby week. Forty years later, Fuller still believes Dancer's Image was disqualified due to these events.