Halperin-Walega E, Batra V K, Tonelli A P, Barr A, Yacobi A
Department of Pharmacodynamics, American Cyanamid Co., Pearl River, New York 10965.
Drug Metab Dispos. 1988 Jan-Feb;16(1):130-4.
The disposition of cefixime, a potent, third generation, orally active cephalosporin, was characterized in the pregnant and lactating rat. After a single iv dose of 17.8 mg/kg 14C-cefixime to day 18 pregnant rats, the half-life for elimination of radioactivity from both maternal serum and placentas was 6.9 hr. Elimination from fetal plasma and tissues was somewhat longer, 12.5 and 13.7 hr, respectively. However, comparison of areas under the curve indicated that exposure of the fetuses to cefixime was far less than that of placentas. Whole body autoradiography showed the greatest radioactivity in maternal liver, kidney, and intestines. In the lactating rat, steady state plasma concentrations of 14C-cefixime were achieved by continuous ip infusion of 2.54 mg/kg/day via Alza osmotic Mini-pumps from days 10 to 14 postpartum. Plasma concentrations of radioactivity in the dams were, on the average, 70 times greater than in their nursing pups throughout the study. After 102 hr of drug infusion, total radioactivity in the body of the pups, including the stomach and intestinal contents, was 1% of the 14C-cefixime estimated to be in the mother's body at steady state. Overall, these data indicate that exposure of the developing rat fetus and nursing pup to cefixime after maternal drug administration is quantitatively small.
头孢克肟是一种强效的第三代口服活性头孢菌素，对妊娠和哺乳期大鼠体内该药的处置情况进行了研究。对妊娠18天的大鼠静脉注射17.8mg/kg的14C-头孢克肟后，母体血清和胎盘放射性消除的半衰期为6.9小时。胎儿血浆和组织的消除时间稍长，分别为12.5小时和13.7小时。然而，曲线下面积比较表明，胎儿接触头孢克肟的量远低于胎盘。全身放射自显影显示母体肝脏、肾脏和肠道的放射性最强。在哺乳期大鼠中，从产后第10天至第14天，通过Alza渗透微型泵连续腹腔注射2.54mg/kg/天的14C-头孢克肟，可达到稳态血浆浓度。在整个研究过程中，母鼠血浆中的放射性浓度平均比其哺乳幼崽高70倍。药物输注102小时后，幼崽体内（包括胃和肠道内容物）的总放射性为稳态时估计母体体内14C-头孢克肟的1%。总体而言，这些数据表明，母体给药后发育中的大鼠胎儿和哺乳幼崽接触头孢克肟的量在数量上很少。
