norgestrel

norgestrel

(nor jess' trel)

Ovrette

Pregnancy Category X

Drug classes

Hormone

Progestin

Hormonal contraceptive

Therapeutic actions

Progestational agent; the endogenous female progestin, progesterone, transforms proliferative endometrium into secretory endometrium; inhibits the secretion of pituitary gonadotropins, which prevents follicular maturation and ovulation; and inhibits spontaneous uterine contractions. The primary mechanism by which norgestrelprevents conception is not known, but progestin-only hormonal contraceptives alter the cervical mucus, exert a progestional effect on the endometrium that interferes with implantation, and in some patients, suppress ovulation.

Indication

·        Prevention of pregnancy using hormonal contraceptives; somewhat less efficacious (3 pregnancies per 100 woman years) than the combined estrogen/progestin hormonal contraceptives (about 1 pregnancy per 100 woman years, depending on formulation)

Contraindications and cautions

·        Contraindicated with allergy to progestins, tartrazine; thrombophlebitis, thromboembolic disorders, cerebral hemorrhage, or history of these conditions; CAD; hepatic disease, carcinoma of the breast or genital organs, undiagnosed vaginal bleeding, missed abortion; as a diagnostic test for pregnancy; pregnancy (fetal abnormalities—masculinization of the female fetus, congenital heart defects, and limb reduction defects); lactation.

·        Use cautiously with epilepsy, migraine, asthma, cardiac or renal dysfunction.

Available forms

Tablets—0.075 mg

Dosages

ADULTS

Administer daily, starting on the first day of menstruation. Take 1 tablet, PO, at the same time each day, every day of the year. Missed dose: 1 tablet—take as soon as remembered, then take the next tablet at regular time; 2 consecutive tablets—take 1 of the missed tablets, discard the other, and take daily tablet at usual time; 3 consecutive tablets—discontinue immediately and use additional form of birth control until menses or pregnancy is ruled out.

Pharmacokinetics

Route	Onset
Oral	Varies

Metabolism: Hepatic; T_1/2: Unknown

Distribution: Crosses placenta; enters breast milk

Excretion: Urine

Adverse effects

·        CNS: Neuro-ocular lesions, mental depression, migraine, changes in corneal curvature, contact lens intolerance

·        CV: Thrombophlebitis, thrombosis, pulmonary embolism, coronary thrombosis, MI, cerebral thrombosis, Raynaud's disease, arterial thromboembolism, renal artery thrombosis, cerebral hemorrhage, hypertension

·        Dermatologic: Rash with or without pruritus, acne, melasma

·        GI: Gallbladder disease, liver tumors, hepatic lesions, nausea, vomiting, abdominal cramps, bloating, cholestatic jaundice

·        GU: Breakthrough bleeding, spotting, change in menstrual flow, amenorrhea, changes in cervical erosion and cervical secretions, endocervicalhyperplasia, vaginal candidiasis

·        Other: Breast tenderness and secretion, enlargement; fluid retention, edema, increase or decrease in weight

Interactions

Drug-drug

·        Decreased effectiveness of hormonal contraceptives with barbiturates, hydantoins, carbamazepine, rifampin, griseofulvin, penicillins, tetracyclines; use alternate form of birth control if these drugs are needed

Drug-alternative therapy

·        Decreased effectiveness if taken with St. John's wort

Nursing considerations

Assessment

·        History: Allergy to progestins, tartrazine; thrombophlebitis, thromboembolic disorders, cerebral hemorrhage; CAD; hepatic disease, carcinoma of the breast or genital organs, undiagnosed vaginal bleeding, missed abortion; epilepsy, migraine, asthma, cardiac or renal dysfunction; pregnancy; lactation

·        Physical: Skin color, lesions, turgor; hair; breasts; pelvic examination; orientation, affect; ophthalmologic examination; P, auscultation, peripheral perfusion, edema; R, adventitious sounds; liver evaluation; LFTs, renal function tests, glucose tolerance, Pap smear, pregnancy test

Interventions

·        Arrange for pretreatment and periodic (at least annual) history and physical, including BP, breasts, abdomen, pelvic organs, and a Pap smear.

·        Start no earlier than 4 wk postpartum for postpartum use.

·        WARNING: Discontinue drug and consult physician if sudden partial or complete loss of vision occurs; if papilledema or retinal vascular lesions are present on examination, discontinue.

·        Discontinue drug and consult physician at any sign of thromboembolic disease—leg pain, swelling, peripheral perfusion changes, shortness of breath.

Teaching points

·        Take exactly as prescribed at intervals not exceeding 24 hours. Take at bedtime or with a meal to establish a routine; medication must be taken daily for prevention of pregnancy; if you miss one tablet, take as soon as remembered, then take the next tablet at regular time. If you miss two consecutive tablets, take one of the missed tablets, discard the other, and take daily tablet at usual time. If you miss three consecutive tablets, discontinue immediately, and use another method of birth control until your cycle starts again. It is a good idea to use an additional method of birth control if any tablets are missed.

·        Discontinue drug and consult your health care provider if you decide to become pregnant. It may be suggested that you use a nonhormonal form of birth control for a few months before becoming pregnant.

·        Do not take this drug during pregnancy; serious fetal abnormalities have been reported. If you think that you are pregnant consult physician immediately.

·        Tell all health care providers, including dentists, that you take this drug. If other medications are prescribed, they may decrease the effectiveness of hormonal contraceptives and an additional method of birth control may be needed.

·        You may experience these side effects: Sensitivity to light (avoid exposure to the sun; use sunscreen and protective clothing); dizziness, sleeplessness, depression (use caution driving or performing tasks that require alertness); rash, skin color changes, loss of hair; fever; nausea; breakthrough bleeding or spotting (transient); intolerance to contact lenses due to corneal changes.

·        Report pain or swelling and warmth in the calves, acute chest pain or shortness of breath, sudden severe headache or vomiting, dizziness or fainting, visual disturbances, numbness or tingling in the arm or leg, breakthrough bleeding or spotting that lasts into the second month of therapy.

Adverse effects in Italic are most common; those in Bold are life-threatening.