Phenylbutazone is an anti-inflammatory drug, which binds to and inactivates cyclooxygenases and prostacyclin synthase through peroxide (H2O2) mediated deactivation. The reduced production of prostaglandin leads to reduced inflammation of the surrounding tissues. Phenylbutazone was marked under the brand name butazolidin for the treatment rheumatoid arthritis and gout, but then this usage was discontinued. In addition, phenylbutazone is used in UK for the treatment of ankylosing spondylitis, but only in those cases, when other therapies are unsuitable.

Clofezone (Perclusone), an analgesic and anti-inflammatory agent, is a drug that was used to treat joint and muscular pain, mostly in rheumatic diseases. Clofezone is a compound preparation of phenylbutazone and clofexamide. Tolerance of Perclusone was very good, no side-effects were observed.