Mestranol

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Cat Number

API0232110

CAS Number

72-33-3

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Product Detail Description Customer Q&A

CAS Number

72-33-3

EINECS

200-777-8

Storage

Store at room temperature

Synonyms

Norquen; Ovastol; Menophase; EE3ME; Mestranolum; Ethynylestradiol 3-methyl ether; 3-Methoxyethynylestradiol; 3-Methylethynylestradiol

Molecular Formula

C21H26O2

Molecular Weight

310.4

Smiles

C[C@]12CC[C@H]3[C@H]([C@@H]1CC[C@]2(C#C)O)CCC4=C3C=CC(=C4)OC

Appearance

White crystalline solid

Melting Point

153-155°C

Boiling Point

464.1°C at 760 mmHg

Relative Density

0.905

General Description

Mestranol is a synthetic estrogen, specifically the 3-methyl ether of ethinylestradiol. It is a prodrug that requires hepatic demethylation to become active ethinylestradiol. The molecule is a 19-nortestosterone derivative with an ethinyl group at the 17α position and a methoxy group at the 3-position.

Mechanism of Action

As a prodrug, mestranol is converted to ethinylestradiol, which binds to estrogen receptors (ERα and ERβ) in target tissues. The receptor complex regulates transcription of genes involved in the reproductive cycle. In oral contraceptives, the estrogen component inhibits gonadotropin (FSH and LH) secretion via negative feedback, preventing ovulation. Mestranol itself has very low affinity for estrogen receptors; its activity depends entirely on bioactivation.

Application

Mestranol was used as the estrogenic component of combined oral contraceptives for pregnancy prevention and for the management of menstrual disorders. It is also employed in some menopausal hormone therapy preparations. Compared to ethinylestradiol, mestranol has a slightly longer half-life due to the demethylation step, but it is also less potent on a milligram basis.

Does Mestranol require protection from light during storage?

Yes, it is photosensitive. Light exposure can cause photodegradation and isomerization. Store in light-resistant, tightly sealed containers, preferably amber glass.

What is the recommended storage temperature for Mestranol?

Store at controlled room temperature (15-25°C). Avoid excessive heat above 30°C, which can accelerate oxidation of the ethinyl group.

Is Mestranol stable in oral contraceptive formulations with progestins?

Yes, when formulated with standard excipients and protected from light and moisture.

How is the impurity ethinyl estradiol (demethylated mestranol) monitored during stability?

This primary degradation product is specifically quantified using a stability-indicating HPLC method, ensuring it remains below USP limits.