Mestranol

Mestranol/Norethidrone

Mechanism :

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).

Indication :

• Oral Contraceptive

Contraindications :

Pregnancy, Estrogen or progesterone dependant cancers, Breast cancer, Uterine cancer, Thrombophlebitis, Smoking.

Dosing :

Adverse Effect :

Fusion of epiphysis and reduction of adult stature.

Serious reactions: Thrombosis/thromboembolism, cerebral hemorrhage, depression, vision changes, hypertension, hepatic adenoma, cholestasis, gallbladder disease, pancreatitis, depression, anaphylaxis, erythema multiforme, SLE exacerbation, porphyria exacerbation, chorea exacerbation, ocular lesions.

Common Reactions: vaginal itching, bleeding irregularities, menstrual cramps, nausea/vomiting, breast tenderness, headache, abdominal distension/pain, edema, weight changes, emotional lability, depression, acne.

Interaction :

Aminophylline: The contraceptive increases the effect and toxicity of theophylline
Amoxicillin, Ampicillin, Carbenicillin, Clavulanate, Cloxacillin, Dicloxacillin, Demeclocycline, Doxycycline, Ketoconazole: This anti-infectious agent could decrease the effect of the oral contraceptive.
Amprenavir, Ritonavir: Could decrease the contraceptive efficacy.
Aprepitant: Could decrease the effect of the oral contraceptive.
Artemether: May decrease the effectiveness of mestranol by increasing its metabolism via CYP3A4.
Benzylpenicillin: This anti-infectious agent could decreases the effect of the oral contraceptive.
Bosentan & Carbamazepine: Decreases the effect of contraceptive.
Colesevelam Bile Acid Sequestrants: May decrease the serum concentration of Contraceptives (Estrogens).
Cyclosporine: The contraceptive increases the effect and toxicity of cyclosporine.
Fosphenytoin, Griseofulvin: This product may cause a slight decrease of contraceptive effect.
Lamotrigine: The oral contraceptive decreases the effect of lamotrigine.
Modafinil: Modafinil decreases the effect of the contraceptive.
Nelfinavir: Ritonavir could decrease the contraceptive efficacy.
Oxcarbazepine: Decreases the effect of the contraceptive.
Oxtriphylline: The contraceptive increases the effect and toxicity of theophylline.
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.
Rifampicin: 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 nonhormonal 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.
Tizanidine: Oral contraceptives decrease the clearance of Tizanidine.
Tolbutamide: This strong CYP2C9 inhibitor, may decrease the metabolism and clearance of Mestranol.
Topiramate: May decrease the effect of the oral contraceptive, Mestranol.
Tretinoin Oral: Tretinoin may decrease the effect of oral contraceptive, Mestranol.
Warfarin: Mestranol may alter the anticoagulant effect of warfarin.

Hepatic Dose :