Of Pills and Eggs: Clomiphene Versus Letrozole

“It’s time to stimulate those ovaries! Dr. Randall A. Loy takes us through a couple scenarios using Clomiphene and Letrozole.

Hi my name is randall loy and i’m an infertility list in orlando florida today we’re going to be talking about some medicines that many of you are familiar with clomid or feh mara the generic names are clomiphene citrate and letrozole i’m going to be talking about the mechanisms of actions of both of those but first you should know that 40% of infertility is

Due to ovulation dysfunction a disorder of ovulation many of those are polycystic ovarian syndrome patients now clomid has been around since the early 1970s and the newcomer letrozole orpha mara has been around and in use since the late 1990s should you use one of the other well your doctor is the best one to make that decision for you based upon your age your

Height your weight your ovarian reserve and other factors so let him or her make that decision for you but i’m gonna talk a little bit about clomid first then letrozole i’m going to go over the mechanisms of action clomid is prescribed usually 1/2 tablet 2 2 tablets a day 4 days 5 6 7 8 and 9 can be days 4 through 8 or 3 through 7 but for 5 cycle days a month you

Would take a tablet or 2 tablets then you would use an ovulation prediction kit or have an ultrasound whatever your doctor decides and you’d time your relations so let’s talk about clomid clomid is an oral medication it’s inexpensive it’s readily available and it has very few side effects probably one in five women might have some side effects in terms of its

Anti estrogen ability meaning maybe some hot flashes or night sweats or vaginal dryness for the first couple of days then those symptoms might flip completely as the estrogen rises and maybe doubles over normal clomid will cause ovulation and 70 to 80 percent of women and 30 to 40% of those women will actually conceive letrozole is also an oral medication it’s

Less available and certainly more expensive so why would one take letrozole over clomid the chances of having twins 0.9% less than 1% whereas the chances for twins with clomid is 7 to 8% i have even had a couple of triplet pregnancies on clomid and i’m not trying to scare you but it is possible in the 13 years we’ve been using the electrodes all and clinic we’ve

Only had five sets of twins and no triplets now a little bit about the mechanism this is something that you can use in your next cocktail party and amaze your friends if not your boss so clomid clomiphene actually blocks estrogen receptors at the hypothalamus and at the pituitary estrogen is made by these cells we’ve talked about before the granulosa cells and

Estrogen feeds back to the pituitary and to the hypothalamus the area that controls the pituitary but it’s blocked out by clomid so even though the estrogen level might be normal the brain is sensing low estrogen low estrogen it sends out a signal increasing the follicle stimulating hormone follicle-stimulating hormone will then come down and increase the number

Of granulosa cells or even cause one of these lessor follicles to develop hence the possibility for twins so you’ll stop taking the clomid and then we would anticipate ovulation some days thereafter you might use an ovulation prediction kit or you might even use a shot of the ovulation trigger hcg to cause that egg to release so now i would like to tell you about

The mechanism of letrozole or tomorrow it too is an oral medication taken for five cycle days each month typically days three through seven luteinizing hormone and other hormones produce androgens like testosterone and andres teen diode in the cells outside of the follicles curiously these androgens have to get across the granulosa cells to be converted into

Estrogens and we use that step as the basis for this particular drugs mechanism so testosterone is converted through the granulosa cells to the biologically most potent estrogen called estradiol and andres teen diode a weaker androgen is converted to a weaker estrogen called s trone so let rizal works on these steps letrozole is a so-called aroma taste enzyme

Inhibitor now aroma taste is the enzyme found throughout the body that converts androgens and estrogens so we take advantage of that fact and what happens is we don’t get the normal amount of estrogen feeding back to the pituitary because we’ve shut that down we’re getting a smaller amount of estrogen feeding back and so the brain perceives too little estrogen

And much like the clomid mechanism when there’s too little estrogen there’s more in the way of follicle stimulating hormone here this will come down and stimulate these cells but different from clemen we typically don’t get a second follicle emerging so the twin rate is about 1% or less so that is the mechanism of letrozole it works on the granulosa cells not

In the brain and pituitary the way clomid does another couple things we talked about clomid being an anti estrogen and that means it has an anti estrogenic effect on the lining to the uterus and on cervical mucus and sometimes that can act against conception letrozole does not do that and locally there’s sufficient estrogen with letrozole to have a thick and more

Hospitable lining one other important difference if you were to take a tablet of colombo feed citrate right now it could still be found in your body five and a half to six weeks from today if you were to take letrozole however it would be completely out of your bloodstream in days and it’s completely out of your body by the time that the embryo makes its way into

The uterus so these medications are not associated with an increased risk in birth defects letrozole has about half the rate as clomid but komen is still within the normal background population in terms of birth defects so the ultimate decision about whether to use clomid or letrozole is up to your doctor he or she will know what’s best for you oftentimes in

A clomid or letrozole syco will perform other tests in that same month a very common test is a post-coital test a post-coital test looks at the interaction between the sperm and the cervical mucus some years ago as i first started practice we did a post-coital test first thing in the afternoon it was a one o’clock appointment and this was the absolute best

Post-coital test we’d ever seen just seeing one or two or three sperm is considered acceptable but we saw literally millions in fact hundreds of millions of sperm in that droplet we could not believe our eyes and i took my senior partner side i said have you ever and all of your life seen a post-coital test like this he said i really haven’t he said this is

Amazing and so i went back to ask the patient i said now you’re supposed to have had intercourse 12 hours ago was was that it she owes well not quite that long i said well what would you estimate 8 hours 10 hours not quite that long well 4 hours 6 hours no not not quite i said well let me ask how long ago was it and she looks at her watch and she says about 10

Minutes and she says i thought it was supposed to be 10 minutes and i said no 10 to 12 hours she goes well that’s why my husband drove his van today we had lunch in the van and then after lunch a little afternoon delight anyway thanks so much for joining me today a lot of crazy stories in our practice as you can tell but a lot of things happen over 30 years anyway

Please subscribe if you haven’t already please tell your friends to subscribe as well and if you have any questions or concerns of a personal nature please email me at the address below i hope to see you again next week thanks so much for joining me today

Transcribed from video
Of Pills and Eggs: Clomiphene Versus Letrozole By InfertilityChannel