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Norethisterone information from DrugsUpdate  

See Available Brands of Norethisterone in India

P - Contraindicated in pregnancy
L - Caution when used during lactation
FI - Food *
LI - Lab *

Norethisterone (or norethindrone) (or 19-nor-17α-ethynyltestosterone) is a molecule used in some combined oral contraceptive pills and in some progestogen only pills. It is a progestogen and can be used to treat premenstrual syndrome, painful periods, abnormal heavy bleeding, irregular periods, menopausal syndrome (in combination with oestrogen), or to postpone a period. Norethindrone was the first orally highly active progestin to be synthesized. It was synthesized for the first time by chemists Luis Miramontes, Carl Djerassi, and George Rosenkranz at Syntex in Mexico City in 1951. It was the progestin used in one of the first two oral contraceptives. It is often used as the related ester, norethisterone acetate.

Pharmacodynamics

Pharmacokinetics

Information Not Available

Norethisterone Indications / Norethisterone Uses

Information Not Available

Norethisterone Adverse Reactions / Norethisterone Side Effects

Norethisterone has typical effects of a progestogen and converts the endometrium from the proliferative to the secretory phase. It may also have some oestrogenic, anabolic and androgenic activities, but these may not be significant. Norethisterone delays onset of periods and controls abnormal uterine bleeding. It also has contraceptive effects due to negative feedback inhibition of pituitary gonadotropin thus preventing ovulation.

Absorption
Absorbed from the GI tract (oral).

Distribution
Highly protein bound

Metabolism
Hepatic; extensive first-pass effect.

Excretion
Via urine (50-80%); via faeces (40%).

Precautions

Information Not Available

Special Precautions

Hypertension; CVS disease; hepatic impairment; epilepsy; lactation; new onset of migraine-type headache; asthma; renal impairment; history of clinical depression.

Other Drug Interactions

Concentration may be reduced by CYP450 inducers (e.g. phenobarbital, phenytoin, carbamazepine, rifampicin, rifabutin, nevirapine, efavirenz, tetracyclines, ampicillin, oxacillin, co-trimoxazole) and ritonavir, nelfinavir (usually inhibitors of CYP450 but have inducing properties when used with steroid hormones). May cause additive fluid retention with NSAIDs, vasodilators. Adjustment in antidiabetic, thyroid hormone and anticoagulant therapy may be required.

Potentially Fatal: May increase ciclosporin concentration.

Other Interactions

Food Interaction
St John's wort may induce norethisterone metabolism, leading to decreased concentrations.

Dosage

Oral
Menorrhagia
Adult: 10-15 mg daily in a cyclical regimen. Usual dose: 5 mg tid for 10 days as primary treatment, subsequently 5 mg bid on days 19-26 of cycle to prevent recurrence. As acetate: 2.5-10 mg daily in a cyclical regimen, beginning during the assumed latter half of the cycle.

Oral

Endometriosis
Adult: 10-25 mg daily continuously for 4-9 months. As acetate: 5-15 mg daily, start at 5 mg daily and increase by 2.5 mg at 14 day intervals. Take continuously for 4-9 months.

Oral

Contraception
Adult: 0.35 mg daily, or 0.5-1 mg daily when combined with oestrogen. As acetate: 0.6 mg daily, or 1-1.5 mg daily when combined with oestrogen.

Oral

Progestogen component of menopausal hormonal replacement therapy
Adult: 0.7 mg as a continuous daily dose. As acetate: 1 mg daily for 10-12 days of a 28-day cycle.

Oral

Premenstrual syndrome
Adult: 5 mg tid on days 16-25 of cycle.

Oral

Breast cancer
Adult: 40 mg daily increasing to 60 mg daily if no regression is noted.

Oral

Postponement of menstruation
Adult: 5 mg tid starting 3 days before expected onset of menstruation.

Intramuscular

Contraception
Adult: As enantate: 200 mg every 8 weeks.

Transdermal

Progestogen component of menopausal hormonal replacement therapy
Adult: As acetate: 140, 170 or 250 mcg/day (as patch), applied twice wkly for 2 weeks of a 4 weeks cycle. Lower strength may also be applied twice weekly on a continuous basis.

Food(before/after)

May be taken with or without food

List of Contraindications

Norethisterone and Pregnancy

Contraindicated in pregnancy

Norethisterone and Lactation

Caution when used during lactation

Norethisterone and Children

Information Not Available

Norethisterone and Geriatic

Information Not Available

Norethisterone and Other Contraindications

Severe hepatic dysfunction; undiagnosed vaginal bleeding; porphyria; pregnancy; previous idiopathic or current thromboembolism; thromboembolic disease; DVT.

Storage

Oral
Store below 25°C.

Transdermal

Store below 25°C.

Lab interference

Oral
Store below 25°C.

Transdermal

Store below 25°C.

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