The effect of a single midcycle administration of 0.5 or 2.0 mg dienogest (17 alpha-cyanomethyl-17 beta-hydroxy-estra-4,9-dien-3-one) on pituitary and ovarian function--investigation for the use as a postcoital contraceptive.

Estradiol-17 beta, progesterone, LH and FSH levels in plasma were measured simultaneously by radioimmunoassay and BBT was recorded in order to investigate the effect of a single midcycle oral dose of 0.5 or 2.0 mg dienogest (17 alpha-cyanomethyl-17 beta-hydroxy-estra-4,9-dien-3-one, VEB Jenapharm, Jena/GDR) on pituitary and ovarian function in 18 healthy fertile females. After application of 0.5 mg dienogest in the follicular phase the cycles appeared to be anovulatory. Administration of 2.0 mg two days prior to the expected LH-surge produced a delay of the LH-peak combined with an absence of ovulation as well as the absence of the normal subsequent increase of progesterone. With 0.5 mg the delay of the LH-surge was followed by an ovulation with normal corpus luteum function. The application of 0.5 or 2.0 mg one day before or during the rising LH-peak lowered the LH-surge but ovulation and luteal phase were not altered. Administration of both dosages during the LH-peak could neither prevent ovulation nor disturb corpus luteum function. Postovulatory ingestion of 0.5 or 2.0 mg dienogest during the BBT-rise produced no alteration of the further cycle. These results demonstrate that dienogest in a single-dose-administration in midcycle can alter pituitary and ovarian function depending on the time interval between application and the day of LH-surge.