The pharmacokinetics of steroïds used in estroprogestative contraception.

The pharmacokinetics of steroïds used in estroprogestative


Christian Jamin

Service Gynécologie Obstétrique, CHU Bichat, Paris, France

Since the day contraceptives were marketed, the tendency has

been to lower steroids doses which, one hoped, would lower secondary effects and

improve tolerance.

At first improvements were spectacular but then, due to the

rarity of secondary effects, results became difficult to measure. The

contraceptive effect of low dose products depends mainly on progestins, which

dose reaches a bottom level due to its blocking power. The progestin dose

determines the oestrogen dose and the adequacy of their proportions as well as

the quality of cycle control. With the progestins available today, the minimum

estrogen dose is 20 micrograms per day for a 21 days cycle.

It has been possible to further diminish the dose of progestins,

and consequently of estrogens, by increasing the duration of treatment to 24

days per cycle, with a slight deterioration of cycle control. The cutaneous way

of administration by patch did not change this last point. However the vaginal

way with a ring has given circulating levels and areas under the steroids curve

equivalent to those of a 15 micrograms pill, but this time with an improvement

of cycle control. Besides, circulating levels are remarkably stable with this


Although studies are rarely comparative, general tolerance also

seems to have been improved.

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