Inhibitory action of dipyrone on rat thyroid peroxidase and lactoperoxidase activities.

ABSTRACT

Previous studies have shown that phenylbutazone, another pyrazolone, inhibits thyroid peroxidase activity and interferes with iodide organification. We have developed [quot ]in vitro[quot ] studies with rat particulated peroxidase and lactoperoxidase (LPO) to study the effects of dipyrone upon thyroid peroxidase and to determine the type of inhibition. The 3-monoiodothyrosine (MIT) and 3,5-diiodothyrosine (DIT) synthesis was markedly affected by 6 X 10(-4) M dipyrone with inhibitions of 59