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Pronunciation |
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(nor
eth IN
drone) |
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U.S. Brand
Names |
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Aygestin®; Micronor®;
NOR-QD® |
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Generic
Available |
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No |
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Synonyms |
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Norethindrone Acetate; Norethisterone |
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Pharmacological Index |
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Contraceptive; Progestin |
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Use |
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Treatment of amenorrhea; abnormal uterine bleeding; endometriosis, oral
contraceptive; higher rate of failure with progestin only
contraceptives |
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Pregnancy Risk
Factor |
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X |
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Contraindications |
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Hypersensitivity to norethindrone; thromboembolic disorders; severe hepatic
disease; breast cancer; undiagnosed vaginal bleeding |
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Warnings/Precautions |
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Use of any progestin during the first 4 months of pregnancy is not
recommended. Discontinue if sudden partial or complete loss of vision,
proptosis, diplopia, or migraine occur. There is a higher rate of failure
with progestin only contraceptives. Progestin-induced withdrawal bleeding
occurs within 3-7 days after discontinuation of drug. Use with caution in
patients with asthma, diabetes, seizure disorder, migraine, cardiac or renal
dysfunction, or psychic depression. |
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Adverse
Reactions |
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>10%:
Cardiovascular: Edema
Endocrine & metabolic: Breakthrough bleeding, spotting, changes in
menstrual flow, amenorrhea
Gastrointestinal: Anorexia
Local: Pain at injection site
Neuromuscular & skeletal: Weakness
1% to 10%:
Cardiovascular: Edema
Central nervous system: Mental depression, fever, insomnia
Dermatologic: Melasma or chloasma, allergic rash with or without pruritus
Endocrine & metabolic: Increased breast tenderness
Gastrointestinal: Weight gain or loss
Genitourinary: Changes in cervical erosion and secretions
Hepatic: Cholestatic jaundice |
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Drug
Interactions |
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Decreased effect: Aminoglutethimide may decrease effects by increasing
hepatic metabolism. Nelfinavir decreases norethindrone
concentrations. |
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Mechanism of
Action |
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Inhibits secretion of pituitary gonadotropin (LH) which prevents follicular
maturation and ovulation |
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Usual Dosage |
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Adolescents and Adults: Female: Oral:
Amenorrhea and abnormal uterine bleeding:
Norethindrone: 5-20 mg/day on days 5-25 of menstrual cycle
Acetate salt: 2.5-10 mg on days 5-25 of menstrual cycle
Endometriosis:
Norethindrone: 10 mg/day for 2 weeks; increase at increments of 5 mg/day
every 2 weeks until 30 mg/day; continue for 6-9 months or until breakthrough
bleeding demands temporary termination
Acetate salt: 5 mg/day for 14 days; increase at increments of 2.5 mg/day
every 2 weeks up to 15 mg/day; continue for 6-9 months or until breakthrough
bleeding demands temporary termination |
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Dietary
Considerations |
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Limit caffeine; high-dose vitamin C (1 g/day) may increase adverse effects;
increase dietary intake of folate and pyridoxine; should be taken with food at
same time each day |
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Mental Health: Effects
on Mental Status |
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May cause insomnia or depression |
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Mental Health:
Effects on Psychiatric
Treatment |
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None reported |
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Dental Health: Local
Anesthetic/Vasoconstrictor
Precautions |
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No information available to require special precautions |
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Dental Health:
Effects on Dental Treatment |
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Until we know more about the mechanism of interaction, caution is required in
prescribing antibiotics to female dental patients taking progestin-only oral
contraceptives |
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Patient
Information |
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Take according to prescribed schedule. Follow instructions for regular
self-breast exam. You may experience dizziness or lightheadedness; use caution
when driving or engaging in tasks that require alertness until response to drug
is known. Limit intake of caffeine. Avoid high-dose vitamin C, folate, or
pyridoxine. You may experience photosensitivity; use sunscreen, wear protective
clothing and eyewear, and avoid direct sunlight. You may experience loss of hair
(reversible), weight gain or loss. Report sudden severe headache or vomiting,
disturbances of vision or speech, sudden blindness, numbness of weakness in an
extremity, chest pain, calf pain, respiratory difficulty, depression or acute
fatigue, unusual bleeding, spotting, or changes in menstrual flow.
Pregnancy/breast-feeding precautions: Inform prescriber if pregnant. Consult
prescriber if breast-feeding. |
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Nursing
Implications |
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Norethindrone acetate is ~2 times as potent as
norethindrone |
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Dosage Forms |
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Tablet: 0.35 mg, 5 mg
Tablet, as acetate: 5 mg |
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