Somatic and skeleton development of rat foetuses following in-utero exposure to isopropylantipyrine (propyphenazone) during the second trimester of gestation.

Isopropylantipyrine (IPA, propyphenazone) is a pyrazolone derivative, widely used as an antipyretic and analgesic drug. The aim of the study was to evaluate the influence of propyphenazone on rat development. IPA was administered to pregnant rats from day 8 to day 14 of pregnancy once a day, orally by a stomach tube at doses of 2.10 (R1), 21.0 (R2), and 210.0 mg/kg/day (R3). The dams were sacrificed on day 21 of gestation and corpora luteum, implants, resorptions, and live foetuses were counted. The weight of foetuses and placentas, the length of foetuses and their tails were checked. The foetuses were fixed in alcohol and skeletons were stained with alizarin. There was a statistical difference in body length in R1, R2 and numbers of subcutaneous ecchymose in R1. External and skeletal examination of the foetuses revealed no evidence of teratogenesis. It can be concluded that IPA has no harmful effects on the prenatal development of the rat offspring at doses used in the present study.