FDA Citizen Petition
Docket No. FDA-2025-P-7111
To whom it may concern,
The undersigned submits this petition under the Federal Food, Drug and Cosmetic Act or the Public Health Service Act or any other statutory provision for which authority has been delegated to the Commissioner of Food and Drugs to request the Commissioner of Food and Drugs to take a form of administrative action.
Section A: Action Requested
I am requesting the section, INDICATIONS AND USAGE, of the Full Prescribing Information for Premarin tablets be updated to include pertinent information about the estrogen hormone, equilin.
From:
INDICATIONS AND USAGE
PREMARIN is a mixture of estrogens indicated for:
To:
INDICATIONS AND USAGE
PREMARIN is a mixture of estrogens and a 17Beta-HSD1 enzyme inhibitor indicated for:
Section B: Statement of Grounds
I am requesting the Full Prescribing Information be updated to include pertinent information about the estrogen hormone, equilin.
Equilin is a major component of Premarin, comprising about 22-30% of Premarin’s ingredients. Being such a large part of Premarin confirms the importance of equilin to carry out the purpose of using Premarin vs using bioidentical estradiol alone.
Estrone is a major component of Premarin, comprising about 52-62% of Premarin’s ingredients. The estrone in Premarin can convert to estradiol via the enzyme 17ẞ-HSD1 (17β-Hydroxysteroid dehydrogenase type 1)
Equilin, according to a peer reviewed paper published in 1999, blocks the 17ẞ-HSD1 enzyme in vitro. According to this paper, it is likely that equilin can also block the 17B-HSD1 enzyme in vivo.
Of course, as we know in science, it is possible that what happens in vitro may not happen in vivo.
However, since there is a possibility that the equilin in Premarin could block estrone converting to estradiol in vivo, it is important to include this information in the Full Prescribing Information for Premarin tablets.
Section C: Environmental Impact
According to section§ 25.30 General subsection (a) and§ 25.31 Human drugs and biologics subsection (a) there is no requirement to provide an environmental impact.
Section D: Economic Impact
not applicable at this time
E. Certification
The undersigned certifies, that, to the best knowledge and belief of the undersigned, this petition includes all information and views on which the petition relies, and that it includes representative data and information known to the petitioner which are unfavorable to the petition.