CENTRAL AND PERIPHERAL PARAMETERS OF THE MENSTRUAL CYCLE UNDER THE INFLUENCE OF A NEW COMBINED ORAL CONTRACEPTIVE

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Abstract
Seven subjects, who were shown to have biphasic cycles were treated with Neogynon® (50 μgethinyl estradiol+250 μg D‐norgestrel). Before and during the treatment cycle serum levels of LH, 17ß‐estradiol and progesterone were estimated by radioimmunossay daily starting on the 8th day of the cycle. In addition BBT, the karyopyknotic index of vaginal smears, cervical function, Spinnbarkeit and crystallization were recorded. Similarly, 5 volunteers were given Neoviettar®* (30 μg ethinyl estradiol+150 μg D‐norgestrel), and both central and peripheral parameters were registered. Results of our experiments indicated that ovulation was suppressed in both groups of patients. It was interesting to note that inhibition of both central and peripheral parameters took place in the patients who were treated with the lower dosed oral contraceptive even in the first medication cycle. Another 5 subjects, who had taken Neogynon® for six months were switched to Neovletta®, and were monitored during their 6th cycle of treatment with the higher dosed combined preparation as well as during the 1st and 3rd cycle of administration of the lower dosed regimen. Analysis of data provides further evidence that ovulation was inhibited even in the first cycle after the switch. The suppression of serum levels of LH, 17ß‐estradiol and progesterone during the Neogynon® cycle was statistically indistinguishable from that during the 1st and 3rd Neovletta® cycle. This observation suggests that the degree of suppression of parameters of cycle function during the administration of combined preparations is apparently influenced by the progestagen‐estrogen ratio. In addition, data obtained in the 1st Neovletta® cycle were not different from those of the 3rd cycle of treatment. Similar results were recorded for the cervical function and the karyopyknotic index. The data of this pilot study combine to provide evidence that Neovletta® provides a very high degree of contraceptive protection even in the first treatment cycle after a switch‐over from a higher dosed pill, since it contains a back‐up mechanism in the case of a breakthrough ovulation. Data presented clearly indicate no such breakthrough ovulations.