I did my research on letrozole. And the 2.5 mg is the standard dosage. Didn't matter if your 200 lbs or 100 lbs, 20 years old or 100 years old. The half life is around 48 hours so it is possible (just my thought) that a person could take it once every 48 hours and you would still have 50 percent of the medication in your system. If you don't take it at all the medication lasts in your system up to a week. So🤷. I wonder if they have done any studies on this dosaging. I don't know why there are not more options on this.