Ravinder P, Nair K M, Sivakumar B
Division of Biophysics, National Institute of Nutrition, (Indian Council of Medical Research), Jamai-Osmania, Hyderabad.
Indian J Physiol Pharmacol. 1998 Oct;42(4):485-90.
Norethisterone enanthate (NET-En) is a well known intramuscular contraceptive drug. The long acting nature of this preparation when administered orally was evaluated in female rats and hamsters using fertility inhibition test and from the plasma levels of norethisterone (NET). An oral dose of 20-60 mg NET-En was administered to random groups of six female rats and hamsters and were mated after five and ten days with males of proven fertility. The fertility inhibition rate was determined from vaginal delivery. A dose-dependent reduction in fertility was seen in rats 5 days after oral administration of NET-En. This effect was found to be less pronounced and not significant 10 days after administration of similar doses of NET-En. In hamsters, a similar but less pronounced effect was noted. The decrease in fertility was significant only at the 60 mg dose. The plasma levels of NET estimated by RIA over a period of 15 days, in a different set of treated rats, suggested rapid absorption of NET-En within a day, and drug concentration decreased slowly, the levels on the 4th day ranged from 0.9-2.3 with the 10 mg and 1.0-4.0 ng/ml with the 20 mg dose. Detection of adequate levels of NET in plasma during the estrous cycle in rats, and the fertility inhibition observed in female rats and at higher doses in hamsters, suggest that NET-En is orally active.
庚酸炔诺酮（NET-En）是一种广为人知的肌肉注射用避孕药。通过生育抑制试验并依据炔诺酮（NET）的血浆水平，在雌性大鼠和仓鼠中评估了该制剂口服时的长效特性。给随机分组的每组6只雌性大鼠和仓鼠口服20 - 60毫克NET-En，在5天和10天后与经证实有生育能力的雄性动物交配。根据阴道分娩情况确定生育抑制率。口服NET-En 5天后，大鼠的生育能力呈剂量依赖性降低。在给予相似剂量的NET-En 10天后，发现这种作用不太明显且无统计学意义。在仓鼠中，观察到类似但不太明显的效果。仅在60毫克剂量时生育能力的降低具有统计学意义。在另一组经处理的大鼠中，通过放射免疫分析法（RIA）在15天内对NET的血浆水平进行评估，结果表明NET-En在一天内迅速吸收，药物浓度缓慢下降，10毫克剂量组第4天的水平范围为0.9 - 2.3纳克/毫升，20毫克剂量组为1.0 - 4.0纳克/毫升。在大鼠发情周期期间血浆中检测到足够水平的NET，以及在雌性大鼠中观察到的生育抑制现象和在仓鼠中较高剂量时出现的生育抑制现象，表明NET-En具有口服活性。
