Oxonic acid and fetal development: II. Teratogenicity in rats

Feeding the uricase inhibitor potassium oxonate (KOx) as 3% of the diet to pregnant rats beginning on the 8th day of gestation for either 2 or 3 days caused a time-related increase in fetal resorptions, with the incidence in the experimental group treated for the additional day being 72% higher than the 2-day group. The shorter treatment period permitted more rat fetuses to survive to term; however 9.3% of these showed gross malformations, exencephaly and/or visceral herniation. Thus, KOx is demonstrated to be both embryotoxic and teratologic in the rat.