SUBCHRONIC STUDIES OF PYRILAMINE IN B6C3F(1) MICE

The purpose of this study was to determine the effects of subchronic e xposure to the antihistamine pyrilamine maleate and to establish dosag e levels to use in a 2-year chronic study. A 14-day repeated-dose stud y in male and female B6C3F1 mice at dietary levels of pyrilamine (as t he free base) of 0, 196, 392, 783, 1563, or 3122 ppm revealed no influ ence on body weight gain and resulted in no deaths, nor abnormal clini cal or gross necropsy observations. Parotid gland cell necrosis was mo re apparent in high-dosage groups than in controls of either gender. M ale and female B6C3F1 mice also were administered pyrilamine for 90 da ys at dietary concentrations of 0, 375, 750, 1500, 3000, or 6000 ppm. Weight gain was markedly suppressed in the 6000 ppm group, but less so at 1500 and 3000 ppm. Parotid gland cell necrosis was apparent in mal es receiving 750 ppm pyrilamine and above and in females at 1500 ppm a nd above. Cytomegaly was noted in the parotid glands of both sexes at midlevel dosages but not in control, low-dosage, or high-dosage animal s. It was concluded that 1500 ppm pyrilamine would not be life-threate ning to B6C3F1 mice in a chronic study.