Name:  Phenylbutazone

Synonyms: Benzone; Butazolidin; Butadion; Mephabutazon; Pyrazolidin;   4-Butyl-1,2-diphenyl-3,5-pyrazolidinedione; 1,2-Diphenyl-3,5-dioxo-4-n-butylpyrazoline

Molecular Structure:  

Molecular Formula:  C₁₉H₂₀N₂O₂

Molecular Weight:  308.38

CAS Number:  50-33-9

EINECS:  200-029-0

 

Phenylbutazone, often referred to as bute, is a crystalline substance having the structure shown at right. Despite its name, phenylbutazone is chemically unrelated to the class of chemicals known as benzones (common examples include oxybenzone, dioxybenzone, avobenzone, and sulisobenzone), which are used as active ingredients in sunscreen formulations for protection against UVB rays.

Phenylbutazone is used as a non-steroidal anti-inflammatory drug (NSAID) for the treatment of chronic pain, including the symptoms of arthritis. Its use is limited by such severe side effects as suppression of white blood cell production and aplastic anemia.

Phenylbutazone is an NSAID commonly used in horses for the following purposes:

Analgesia: Pain relief from infections and musculoskeletal disorders including sprains, overuse injuries, tendinitis, arthralgias, arthritis, and laminitis. Like other NSAIDs, acts directly on musculoskeletal tissue to control inflammation, thereby reducing secondary inflammatory damage, alleviating pain, and restoring range of motion. Does not cure musculoskeletal ailments or work well on colic pain.

Antipyresis: Reduction of fevers. Antipyretic qualities may mask other symptoms; therefore, should not be administered for this purpose unless a veterinarian has concluded that the horse would not be able to eat or drink without its use or that the fever might hinder the horse's recovery.