indication

Mestranol was used as one of the first oral contraceptives.

mechanism of action

Mestranol is the 3-methyl ether of ethinylestradiol. Ethinylestradiol, is a synthetic derivative of estradiol. Ethinylestradiol is orally bio-active and the estrogen used in almost all modern formulations of combined oral contraceptive pills. It binds to (and activates) the estrogen receptor. Mestranol is a biologically inactive prodrug of ethinylestradiol to which it is demethylated in the liver with a conversion efficiency of 70%. Estrogens diffuse into their target cells and interact with a protein receptor. Target cells include the female reproductive tract, the mammary gland, the hypothalamus, and the pituitary. Estrogens increase the hepatic synthesis of sex hormone binding globulin (SHBG), thyroid-binding globulin (TBG), and other serum proteins and suppress follicle-stimulating hormone (FSH) from the anterior pituitary. The combination of an estrogen with a progestin suppresses the hypothalamic-pituitary system, decreasing the secretion of gonadotropin-releasing hormone (GnRH).

drug interactions

Aminophylline: The contraceptive increases the effect and toxicity of theophylline

Amoxicillin: This anti-infectious agent could decrease the effect of the oral contraceptive

Ampicillin: This anti-infectious agent could decrease the effect of the oral contraceptive

Amprenavir: Ritonavir could decrease the contraceptive efficacy

Aprepitant: Aprepitant could decrease the effect of the oral contraceptive

Artemether: Artemether may decrease the effectiveness of mestranol by increasing its metabolism via CYP3A4. Consider an alternate non-hormonal means of contraception during artemether therapy.

Bosentan: Decreases the effect of contraceptive

Carbamazepine: This product may cause a slight decrease of contraceptive effect

Carbenicillin: This anti-infectious agent could decreases the effect of the oral contraceptive

Clavulanate: This anti-infectious agent could decrease the effect of the oral contraceptive

Cloxacillin: This anti-infectious agent could decrease the effect of the oral contraceptive

Colesevelam: Bile Acid Sequestrants may decrease the serum concentration of Contraceptives (Estrogens). Administer estrogen-based oral contraceptives at least 1-4 hours prior to or 4-6 hours after administration of a bile acid sequestrant. Consider alternatives in order to avoid this combination when possible, due to the risk for impaired contraceptive effectiveness. Ethinyl estradiol patches and vaginal rings may also be somewhat impacted by this interaction, though the extent and significance of such an interaction is uncertain.

Cyclosporine: The contraceptive increases the effect and toxicity of cyclosporine

Demeclocycline: This anti-infectious agent could decrease the effect of the oral contraceptive

Dicloxacillin: This anti-infectious agent could decrease the effect of the oral contraceptive

Doxycycline: This anti-infectious agent could decrease the effect of the oral contraceptive

Flucloxacillin: This anti-infectious agent could decrease the effect of the oral contraceptive

Fosphenytoin: This product may cause a slight decrease of contraceptive effect

Griseofulvin: This product may cause a slight decrease of contraceptive effect

Itraconazole: This anti-infectious agent could decrease the effect of the oral contraceptive

Ketoconazole: This anti-infectious agent could decrease the effect of the oral contraceptive

Lamotrigine: The oral contraceptive decreases the effect of lamotrigine

Minocycline: This anti-infectious agent could decrease the effect of the oral contraceptive

Modafinil: Modafinil decreases the effect of the contraceptive

Nelfinavir: Ritonavir could decrease the contraceptive efficacy

Oxcarbazepine: Oxcarbazepine decreases the effect of the contraceptive

Oxtriphylline: The contraceptive increases the effect and toxicity of theophylline

Penicillin G: This anti-infectious agent could decreases the effect of the oral contraceptive

Penicillin V: This anti-infectious agent could decrease the effect of the oral contraceptive

Phenobarbital: This product may cause a slight decrease of contraceptive effect

Phenytoin: This product may cause a slight decrease of contraceptive effect

Pioglitazone: Possible loss of contraceptive effect

Piperacillin: This anti-infectious agent could decrease the effect of the oral contraceptive

Pivampicillin: This anti-infectious agent could decrease the effect of the oral contraceptive

Prednisolone: The estrogenic agent, mestranol, may increase the effect of the corticosteroid, prednisolone.

Prednisone: The estrogenic agent, mestranol, may increase the effect of corticosteroid, prednisone.

Primidone: This product may cause a slight decrease of contraceptive effect

Raloxifene: Association not recommended

Rifabutin: This product may cause a slight decrease of the contraceptive effect

Rifampin: This product may cause a slight decrease of contraceptive effect

Tetracycline: This anti-infectious agent could decrease the effect of the oral contraceptive

Theophylline: The contraceptive increases the effect and toxicity of theophylline

Thiopental: Thiopental may decrease the effect of Mestranol. Contraceptive failure may occur. Alternative nonhomomonal contraception should be used during concomitant therapy.

Tipranavir: Mestranol may increase the adverse dermatological effects (i.e. skin rash) of Tipranavir. Tipranavir may decrease the serum concentration Mestranol. Use an alternate form of contraception or monitor for estrogen deficiency if Mestranol is used for hormone replacement therapy.

Tizanidine: Oral contraceptives decrease the clearance of Tizanidine.

Tolbutamide: Tolbutamide, a strong CYP2C9 inhibitor, may decrease the metabolism and clearance of Mestranol. Consider alternate therapy or monitor for changes in Mestranol therapeutic and adverse effects if Tolbutamide is initiated, discontinued or dose changed.

Topiramate: Topiramate may decrease the effect of the oral contraceptive, Mestranol. An alternate form of contraception should be used during concomitant therapy.

Tretinoin: Oral Tretinoin may decrease the effect of oral contraceptive, Mestranol. An alternate form of contraception should be used during concomitant therapy.

Warfarin: Mestranol may alter the anticoagulant effect of warfarin. Concomitant therapy should be avoided. Monitor for changes in coagulation status if mestranol is initiated, discontinued or dose changed.