Serum estrogens and ovulation return in chronic users of a once-a-month injectable contraceptive

To determine whether the long-term exposure to a monthly injectable contraceptive, containing dihydroxyprogesterone acetophenide 150 mg and estradiol enanthate 10 mg, induces significant changes on the serum estrogens profile and ovulation return in women, a study in chronic users was undertaken. Ovarian function was assessed for 3 months following a single injection of the contraceptive agent in a group of women (n = 7) who have been on this formulation for an average period of 6.7 years and in a non-user control group (n = 7). The serum concentrations of 17 beta-estradiol, estrone and progesterone were measured in samples drawn at regular intervals throughout the entire study. The endometrial bleeding pattern was recorded in all subjects. The results indicated that the post-injection serum estradiol maximum levels (exogenous peak) occurred significantly earlier (p less than 0.05) in chronic users as compared with the non-user control group. Baseline serum estrone concentrations were slightly higher in chronic users than those observed in the control group, while the values of serum 17 beta-estradiol did not exhibit significant differences among the two groups. Ovulation was documented within 60-90 days after injection in all subjects from both groups. A similar length of the first bleeding-free period was observed in all participants. The overall data provide evidence of a moderate increase of estrone, one of the still active metabolic conversion products of 17 beta-estradiol, in the sera of chronic users of this combined contraceptive without affecting its pharmacodynamics.