Toivonen J, Lähteenmäki P, Luukkainen T
Contraception. 1979 Jul;20(1):11-8. doi: 10.1016/0010-7824(79)90040-4.
Levonorgestrel and estradiol releasing contraceptive vaginal rings (CVR) with an outer diameter of 50 mm were used by twenty women. The treatment was given in three-week cycles followed by one treatment-free week. The treatment was planned to cover six cycles. All subjects kept records of bleeding and were controlled clinically in the course of treatment. Three subjects were followed by blood sampling. Plasma levonorgestrel, estradiol, progesterone and gonadotropins were determined. The subjects experienced no difficulties in using the CVR and 90 per cent continued the treatment through the whole experimental period of six months. One subject discontinued after three cycles because of irregular bleedings and one subject after five cycles because of urinary discomfort. Regular bleedings were observed only in three subjects and in nine cases the bleeding started with the CVR in situ during the last days of the three-week treatment period. Breakthrough bleeding occurred in the remaining eight subjects. The subjective side-effects were as follows: weight gain in four subjects, oedema in one subject and urinary discomfort in one subject. Pituitary function was not generally suppressed as judged by plasma gonadotropins. Out of the three subjects studied, two experienced ovulatory plasma progesterone concentrations.
20名女性使用了外径为50毫米的左炔诺孕酮和雌二醇释放型避孕阴道环（CVR）。治疗以三周为一个周期，之后有一周的无治疗期。该治疗计划进行六个周期。所有受试者记录出血情况，并在治疗过程中接受临床检查。对三名受试者进行了采血。测定了血浆中的左炔诺孕酮、雌二醇、孕酮和促性腺激素。受试者在使用CVR时未遇到困难，90%的受试者在整个六个月的实验期内持续接受治疗。一名受试者在三个周期后因不规则出血而停药，一名受试者在五个周期后因尿道不适而停药。仅在三名受试者中观察到规律出血，在九例中，出血在三周治疗期的最后几天CVR在位时开始。其余八名受试者出现突破性出血。主观副作用如下：四名受试者体重增加，一名受试者出现水肿，一名受试者有尿道不适。根据血浆促性腺激素判断，垂体功能一般未受抑制。在研究的三名受试者中，有两名出现了排卵时的血浆孕酮浓度。
