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Look Up > Drugs > Ethinyl Estradiol and Norethindrone
Ethinyl Estradiol and Norethindrone
Pronunciation
U.S. Brand Names
Generic Available
Synonyms
Pharmacological Index
Use
Pregnancy Risk Factor
Contraindications
Warnings/Precautions
Adverse Reactions
Overdosage/Toxicology
Drug Interactions
Mechanism of Action
Pharmacodynamics/Kinetics
Usual Dosage
Dietary Considerations
Test Interactions
Dental Health: Local Anesthetic/Vasoconstrictor Precautions
Dental Health: Effects on Dental Treatment
Patient Information
Nursing Implications
Dosage Forms

Pronunciation
(ETH in il es tra DYE ole & nor eth IN drone)

U.S. Brand Names
Brevicon®; Estrostep® 21; Estrostep® Fe; Femhrt™; Genora® 0.5/35; Genora® 1/35; Jenest-28™; Loestrin®; Modicon™; N.E.E.® 1/35; Nelova™ 0.5/35E; Nelova™ 10/11; Norethin™ 1/35E; Norinyl® 1+35; Ortho-Novum® 1/35; Ortho-Novum® 7/7/7; Ortho-Novum® 10/11; Ovcon® 35; Ovcon® 50; Tri-Norinyl®

Generic Available

Yes


Synonyms
Norethindrone Acetate and Ethinyl Estradiol

Pharmacological Index

Contraceptive


Use

Prevention of pregnancy; treatment of hypermenorrhea, endometriosis, female hypogonadism, moderate to severe vasomotor symptoms associated with menopause; prevention of osteoporosis


Pregnancy Risk Factor

X


Contraindications

Thrombophlebitis, cerebral vascular disease, coronary artery disease, known or suspected breast carcinoma, undiagnosed abnormal genital bleeding, hypersensitivity to any component; pregnancy


Warnings/Precautions

Use of any progestin during the first 4 months of pregnancy is not recommended; in patients with a history of thromboembolism, stroke, myocardial infarction (especially >40 years of age who smoke), liver tumor, hypertension, cardiac, renal or hepatic insufficiency; risk of cardiovascular side effects increases in those women who smoke cigarettes and in women >35 years of age.


Adverse Reactions

>10%:

Cardiovascular: Peripheral edema

Endocrine & metabolic: Enlargement of breasts, breast tenderness

Gastrointestinal: Nausea, anorexia, bloating

1% to 10%:

Central nervous system: Headache

Endocrine & metabolic: Increased libido

Gastrointestinal: Vomiting, diarrhea

<1%: Hypertension, thromboembolism, stroke, myocardial infarction, edema, depression, dizziness, anxiety, chloasma, melasma, rash, decreased glucose tolerance, breast tumors, amenorrhea, alterations in frequency and flow of menses, increased triglycerides and LDL, GI distress, cholestatic jaundice, intolerance to contact lenses, increased susceptibility to Candida infection

Minimize these effects by adjusting the estrogen/progestin balance or dosage. The table categorizes products by both their estrogenic and progestational potencies; because overall activity is influenced by the interaction of components, it is difficult to precisely classify products; placement in the table is only approximate. Differences between products within a group are probably not clinically significant.

Hormonal Balance in Oral Contraceptives:

Estrogen Excess: Nausea, bloating, cervical mucorrhea, polyposis, melasma, migraine headache, breast fullness or tenderness, edema, hypertension

Estrogen Deficiency: Early or midcycle breakthrough bleeding, increased spotting, hypomenorrhea

Progestin Excess: Increased appetite, weight gain, tiredness, fatigue, hypomenorrhea, acne, oily scalp*, hair loss, hirsutism*, depression, monilial vaginitis, breast regression

Progestin Deficiency: Late breakthrough bleeding, amenorrhea, hypermenorrhea

*Result of androgenic activity of progestins

Pharmacological effects of progestins used in oral contraceptives:

Norgestrel/levonorgestrel:

Progestin: Pronounced effect

Estrogen: No effect

Antiestrogen: Moderate effect

Androgen: Pronounced effect

Ethynodiol diacetate:

Progestin: Moderate effect

Estrogen: Slight effect*

Antiestrogen: Slight effect*

Androgen: Slight effect

Norethindrone acetate:

Progestin: Slight effect

Estrogen: Slight effect

Antiestrogen: Pronounced effect

Androgen: Slight effect

Norethindrone:

Progestin: Slight effect

Estrogen: Slight effect*

Antiestrogen +*

Androgen: Slight effect

Norethynodrel:

Progestin: Slight effect

Estrogen: Pronounced effect

Antiestrogen: No effect

Androgen: No effect

*Has estrogenic effect at low doses; may have antiestrogenic effect at higher doses.


Overdosage/Toxicology

Toxicity is unlikely following single exposures of excessive doses

Any treatment following emesis and charcoal administration should be supportive and symptomatic


Drug Interactions

Ethinyl estradiol is a CYP3A3/4 and 3A5-7 enzyme substrate; CYP1A2 enzyme inhibitor

Potential contraceptive failure with barbiturates, hydantoins, and rifampin, nelfinavir.

Concomitant penicillins or tetracyclines may lead to contraceptive failure

Increased toxicity:

Increased toxicity of carbamazepine, tricyclic antidepressants, and corticosteroids

Increased thromboembolic potential with oral anticoagulants


Mechanism of Action

Combination oral contraceptives inhibit ovulation via a negative feedback mechanism on the hypothalamus, which alters the normal pattern of gonadotropin secretion of a follicle-stimulating hormone (FSH) and luteinizing hormone by the anterior pituitary. The follicular phase FSH and midcycle surge of gonadotropins are inhibited. In addition, oral contraceptives produce alterations in the genital tract, including changes in the cervical mucus, rendering it unfavorable for sperm penetration even if ovulation occurs. Changes in the endometrium may also occur, producing an unfavorable environment for nidation. Oral contraceptive drugs may alter the tubal transport of the ova through the fallopian tubes. Progestational agents may also alter sperm fertility.


Pharmacodynamics/Kinetics

Ethinyl estradiol:

Absorption: Absorbed well from GI tract

Protein binding: 98%

Metabolism: Inactivated by liver

Half-life: 6-20 hours

Elimination: Bile and urine, enterohepatic recycling

Norethindrone:

Bioavailability: Overall 65% with first-pass metabolism

Half-life, terminal: 5-14 hours

Time to peak: Oral: 0.5-4 hours


Usual Dosage

Oral: Adults: Female: Contraception:

For 21-tablet package: Dosage is 1 tablet daily for 21 consecutive days, followed by 7 days off of the medication; a new course begins on the 8th day after the last tablet is taken.

For 28-tablet package: Dosage is 1 tablet daily without interruption.

Schedule 2 (Day 1 starter): Dose starts on first day of menstrual cycle taking 1 tablet daily.

For 21-tablet package: Dosage is 1 tablet daily for 21 consecutive days, followed by 7 days off of the medication; a new course begins on the 8th day after the last tablet is taken.

For 28-tablet package: Dosage is 1 tablet daily without interruption.

If all doses have been taken on schedule and one menstrual period is missed, continue dosing cycle. If two consecutive menstrual periods are missed, pregnancy test is required before new dosing cycle is started.

Missed doses monophasic formulations (refer to package insert for complete information):

One dose missed: Take as soon as remembered or take 2 tablets next day

Two consecutive doses missed in the first 2 weeks: Take 2 tablets as soon as remembered or 2 tablets next 2 days. An additional method of contraception should be used for 7 days after missed dose.

Two consecutive doses missed in week 3 or three consecutive doses missed at any time: An additional method of contraception must be used for 7 days after a missed dose.

Schedule 1 (Sunday starter): Continue dose of 1 tablet daily until Sunday, then discard the rest of the pack, and a new pack should be started that same day.

Schedule 2 (Day 1 starter): Current pack should be discarded, and a new pack should be started that same day.

Missed doses biphasic/triphasic formulations (refer to package insert for complete information):

One dose missed: Take as soon as remembered or take 2 tablets next day.

Two consecutive doses missed in week 1 or week 2 of the pack: Take 2 tablets as soon as remembered and 2 tablets the next day. Resume taking 1 tablet daily until the pack is empty. An additional method of contraception should be used for 7 days after a missed dose.

Two consecutive doses missed in week 3 of the pack; An additional method of contraception must be used for 7 days after a missed dose.

Schedule 1 (Sunday Starter): Take 1 tablet every day until Sunday. Discard the remaining pack and start a new pack of pills on the same day.

Schedule 2 (Day 1 starter): Discard the remaining pack and start a new pack the same day.

Three or more consecutive doses missed; An additional method of contraception must be used for 7 days after a missed dose.

Schedule 1 (Sunday Starter): Take 1 tablet every day until Sunday; on Sunday, discard the pack and start a new pack.

Schedule 2 (Day 1 Starter): Discard the remaining pack and begin new pack of tablets starting on the same day.


Dietary Considerations

Should be administered with food at same time each day


Test Interactions

Decreased antithrombin III

Decreased serum folate concentration

Increased prothrombin and factors VII, VIII, IX, X

Increased platelet aggregability

Increased thyroid binding globulin

Increased total thyroid hormone (T4)

Increased serum triglycerides/phospholipids


Dental Health: Local Anesthetic/Vasoconstrictor Precautions

No information available to require special precautions


Dental Health: Effects on Dental Treatment

When prescribing antibiotics, patient must be warned to use additional methods of birth control if taking oral contraceptives


Patient Information

Take exactly as directed; use additional method of birth control during first week of administration of first cycle; photosensitivity may occur. Women should inform their physicians if signs or symptoms of any of the following occur thromboembolic or thrombotic disorders including sudden severe headache or vomiting, disturbance of vision or speech, loss of vision, numbness or weakness in an extremity, sharp or crushing chest pain, calf pain, shortness of breath, severe abdominal pain or mass, mental depression, or unusual bleeding.

Women should discontinue taking the medication if they suspect they are pregnant or become pregnant


Nursing Implications

Administer at bedtime to minimize occurrence of adverse effects


Dosage Forms

Tablet:

Estrostep®:

Triangular tablet (white): Ethinyl estradiol 0.02 mg and norethindrone acetate 1 mg

Square tablet (white): Ethinyl estradiol 0.03 mg and norethindrone acetate 1 mg

Round tablet (white): Ethinyl estradiol 0.035 mg and norethindrone acetate 1 mg

Estrostep® Fe:

Triangular tablet (white): Ethinyl estradiol 0.02 mg and norethindrone acetate 1 mg

Square tablet (white): Ethinyl estradiol 0.03 mg and norethindrone acetate 1 mg

Round tablet (white): Ethinyl estradiol 0.035 mg and norethindrone acetate 1 mg

Brown tablet: Ferrous fumarate 75 mg

Loestrin® 1.5/30: Ethinyl estradiol 0.03 mg and norethindrone acetate 1.5 mg (21s)

Loestrin® Fe 1.5/30: Ethinyl estradiol 0.03 mg and norethindrone acetate 1.5 mg with ferrous fumarate 75 mg in 7 inert tablets (28s)

Loestrin® 1/20: Ethinyl estradiol 0.02 mg and norethindrone acetate 1 mg (21s)

Loestrin® Fe 1/20: Ethinyl estradiol 0.02 mg and norethindrone acetate 1 mg with ferrous fumarate 75 mg in 7 inert tablets (28s)

Genora® 1/35, N.E.E.® 1/35, Nelova® 1/35E, Norethin™ 1/35E, Norinyl® 1+35, Ortho-Novum® 1/35: Ethinyl estradiol 0.035 mg and norethindrone 1 mg (21s, 28s)

Jenest-28™: Phase 1 (7 white tablets): Ethinyl estradiol 0.035 mg and norethindrone 0.5 mg; Phase 2 (14 peach tablets): Ethinyl estradiol 0.035 mg and norethindrone 1 mg and 7 green inert tablets (28s)

Ortho-Novum® 7/7/7: Phase 1 (7 white tablets): Ethinyl estradiol 0.035 mg and norethindrone 0.5 mg; Phase 2 (7 light peach tablets): Ethinyl estradiol 0.035 mg and norethindrone 0.75 mg; Phase 3 (7 peach tablets): Ethinyl estradiol 0.035 mg and norethindrone 1 mg (21s, 28s)

Ortho-Novum® 10/11: Phase 1 (10 white tablets): Ethinyl estradiol 0.035 mg and norethindrone 0.5 mg; Phase 2 (11 dark yellow tablets): Ethinyl estradiol 0.035 mg and norethindrone 1 mg (21s, 28s)

Ovcon® 35: Ethinyl estradiol 0.035 mg and norethindrone 0.4 mg (21s, 28s)

Ovcon® 50: Ethinyl estradiol 0.050 mg and norethindrone 1 mg (21s, 28s)

Tri-Norinyl®: Phase 1 (7 blue tablets): Ethinyl estradiol 0.035 mg and norethindrone 0.5 mg; Phase 2 (9 green tablets): Ethinyl estradiol 0.035 mg and norethindrone 1 mg; Phase 3 (5 blue tablets): Ethinyl estradiol 0.035 mg and norethindrone 0.5 mg (21s, 28s)


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