Abstract

Nifenazone (Thylin - West Pharmaceutical Co) is a pyrazole derivative (amidopyrine is 4-dimethyl-amino-phenazone). It is described as ‘a potent non-hormonal antirheumatic agent of low toxicity.’ In animal experiments the compound has an analgesic effect comparable to that of phenazone whilst its median lethal dose (LD50) is somewhat higher¹.