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Look Up > Drugs > Ethinyl Estradiol and Norgestrel
Ethinyl Estradiol and Norgestrel
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 JES trel)

U.S. Brand Names
Lo/Ovral®; Ovral®

Generic Available

Yes


Synonyms
Morning After Pill; Norgestrel and Ethinyl Estradiol

Pharmacological Index

Contraceptive


Use

Prevention of pregnancy; oral: postcoital contraceptive or "morning after" pill; treatment of hypermenorrhea, endometriosis, female hypogonadism


Pregnancy Risk Factor

X


Contraindications

Thromboembolic disorders, cerebrovascular or coronary artery disease; known or suspected breast cancer; undiagnosed abnormal vaginal bleeding; women smokers >35 years of age; all women >40 years of age, hypersensitivity to drug or components; 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

Effects can be minimized by adjusting the estrogen/progestin balance or dosage. See tables in Ethinyl Estradiol and Norethindrone monograph.

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, myocardial infarction, edema, depression, dizziness, anxiety, stroke, 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


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

Norgestrel:

Metabolism: Reduction and conjugation

Bioavailability: Complete with no first-pass effect

Half-life, terminal: 11-45 hours

Time to peak: 0.5-2 hours


Usual Dosage

Oral: Adults: Female: Contraception: Some products recommend starting with one schedule over the other (refer to product information for more details):

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: Schedule 1 (Sunday starter): Continue to take 1 tablet daily until Sunday, then discard the rest of the pack, and a new pack is started that same day. Schedule 2 (Day 1 starter): Current pack should be discarded, and a new pack started that same day. An additional method of contraception should be used for 7 days after missed dose.

Postcoital contraception or "morning after" pill: Oral (50 mcg ethinyl estradiol and 0.5 mg norgestrel): 2 tablets at initial visit and 2 tablets 12 hours later


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 on 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:

Ovral®: Ethinyl estradiol 0.05 mg and norgestrel 0.5 mg (21s and 28s)

Low-Ogestrel®: Bioequivalent to Lo/Ovral®


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