Toivonen J, Lähteenmäki P, Luukkainen T
Contraception. 1978 Sep;18(3):201-11. doi: 10.1016/s0010-7824(78)80014-6.
Four women used polysiloxane contraceptive rings (CVR) impregnated with d-Norgestrel and estradiol for contraceptive purposes. The treatment was given in three-week cycles, leaving one treatment-free week between the cycles. Subjects were followed by blood sampling twice a week for three or four treatment cycles. Plasma concentrations of d-Norgestrel, estradiol, progesterone, and gonadotropins were determined by radioimmunoassay. The bleeding patterns were very acceptable. One subject experienced acne and weight gain, but no other side-effects were observed. Furthermore, no local irritation was found during the follow-up period of six or seven months. The individual variation in the mean plasma concentrations of d-norgestrel was between 3.2 and 1.1 ng/ml. Apart from one case, the highest individual levels were observed at the beginning of the first treatment cycle. Plasma estradiol was low during the treatment, but in some cases low post-insertion peaks were observed. No ovulatory progesterone values were found. Plasma LH was generally suppressed, but FSH was not. During the treatment-free week increasing concentrations of both LH and FSH were found, indicating an activation of pituitary function.
四名女性使用了浸渍有炔诺孕酮和雌二醇的聚硅氧烷避孕环（CVR）用于避孕。治疗以三周为一个周期进行，周期之间有一周无治疗期。受试者每周进行两次血液采样，持续三到四个治疗周期。通过放射免疫分析法测定血浆中炔诺孕酮、雌二醇、孕酮和促性腺激素的浓度。出血模式非常令人满意。一名受试者出现痤疮和体重增加，但未观察到其他副作用。此外，在六到七个月的随访期内未发现局部刺激。炔诺孕酮平均血浆浓度的个体差异在3.2至1.1 ng/ml之间。除了一个病例外，最高个体水平在第一个治疗周期开始时观察到。治疗期间血浆雌二醇水平较低，但在某些情况下插入后出现低峰。未发现排卵时的孕酮值。血浆促黄体生成素（LH）通常受到抑制，但促卵泡生成素（FSH）未受抑制。在无治疗期，发现LH和FSH的浓度均增加，表明垂体功能被激活。
