Phenylbutazone (butazolidin®) is one of a group of pyrazole derivatives developed by the chemists of the J. R. Geigy Co., of Basel, Switzerland, in an attempt to find compounds with pharmacologie properties similar to aminopyrine but without its toxicity (see accompanying figure). Many clinical trials have been conducted in Switzerland and Germany, with a combination of aminopyrine and phenylbutazone in equal parts (the mixture is known as irgapyrin® in Europe and butapyrin® in this country.1) These studies were initiated since phenylbutazone was found to promote the solubility of the relatively insoluble aminopyrine, thus permitting its parenteral use. There have been no reports of extensive clinical trials of phenylbutazone alone, whereas the clinical effects and toxicity of aminopyrine are well known. Since the antirheumatic properties of the mixture have been so favorable, it was desirable to evaluate phenylbutazone separately.
Considerable pharmacologic investigation has been reported. Wilhelmi1a demonstrated that phenylbutazone