Pyrazolone Derivatives

Pyrazolone Derivatives

Phenylbutazone (Butazolidin) is metabolized to oxy-phenbutazone (Phlogistol), and both compounds have all of the activities associated with the NSAIDs. Their use is accompanied by serious adverse reactions, such as anemia, nephritis, renal failure or necrosis, and liver damage. Because of their toxicity, they are prescribed only for the treatment of pain associated with gout or phlebitis or as a last resort for other painful inflamma-tory diseases resistant to newer and less toxic treat-ments. Interactions with a large number of other drugs (similar to those described for aspirin) occur, since phenylbutazone displaces several drugs from plasma protein binding sites. The drug is contraindicated in chil-dren and in the elderly with diminished renal function. The consequences of overdose occur slowly and can in-clude liver damage, renal failure, and shock. There is no antidote for overdose. Supportive measures include ventilation, dialysis, and gastric lavage with activated charcoal, as well as the use of benzodiazepines to con-trol convulsions.