Mifepristone and menses

[countryboy75]

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In my preparation for step 1 of course I came across mifepristone in my pharm studies and I have a question that surprisingly no sources I have looked into have been able to answer and that is:

With mifepristone being a progesterone antagonist I understand that it induces shedding of the endometrium thus effectively preventing implantation. However, once mifepristone is used and endometrial shedding occurs what does that do to the ovulatory/menses cycle? will the patient "reset" their menses and begin a new menses cycle or will they effectively have two menses approximately 7-14 days apart?

The reason I am asking this on here is that I asked my clinical medicine prof (a retired IM doc) and he said "I dunno, I have been out of the game too long" and when I asked another friend in IM he said "that sounds more like a ob/gyn boards question than a USMLE question"

In any event I would like to know what you folks know about this. Whether or not I will have this on my boards because I find this to be a relative question to current medicine.

 

[dreammerchants]

I am not sure why you would worry about the effect of RU-486 on menstrual cycle.....its use is meant to be for either emergency contraception or used as an abortifacient (between 13 to 24 weeks gestation)....so they are short term doses so effect on menses does not come into play. You would not be using it chronically as a birth control pill.

You would not want to use a progesterone antagonist long term cause that would leave uninhibited estrogen and hence increase risk of hyperplasia and cancer. If say you were to inhibit progesterone (well then you would get intermenstrual bleeding and abnormal menstrual bleeding cause you are basically inducing a state similar to anovulation where you have estrogen but no progesteron !!

Thats my 2 cents ... I never thought of Ru-486 being used chronically !!

 

[countryboy75]

I am not talking about using it chronically. I am asking about the use of mifepristone as an abortifacient in an isolated case.

For instance:


24 y/o female college student comes to my office after taking mifepristone two days prior and states "I bled after I took the pill, when can I expect to have my period again" last known menses was 12 days prior

or

36 y/o female requires a D&C, prior to the surgery the physician gives the patient mifepristone to loosen the endometrium. At the 10 day follow up the patient asks when will I menstruate again

I understand mifepristone is a progesterone antagonist and therefore causes endometrial shedding, however, with the sudden decrease in progesterone and hence shedding does the pituitary axis involved read this as a generalized menses or (assuming the patient is at day 14) will another menses occur 14 days later?

 

[doc erica]

This is a question that would take you back to reproductive physiology. When using Mifepristone for an induced abortion, usually along with Misoprostil for uterine contraction, you are removing all products of conception. Therefore by removing it, you no longer have the secretion of HCG. HCG's most important function in the early stages of pregnancy is to maintain the corpus luteum, so that it itself can continue to release estrogens and progesterone.

Now with the products of conception removed, there would soon be a drastic decrease in progesterone and then FSH released from the pituitary will begin to rise, as it is no longer under negative feedback from progesterone. The rise in FSH again will prepare your patient for the next reproductive cycle; 28 days if it's the perfect scenario, but I would think it may take a bit longer for hormonal levels to fall after the induced abortion. Hope that helps!

 

[countryboy75]

thank you very much erica, that is what I thought, I was just a liitle unsure.