NORETHINDRONE

NORETHINDRONE
(nor-eth-in'drone)
Micronor, Norlutin, Nor-Q.D.
NORETHINDRONE ACETATE
Aygestin

, Norlutate

Classifications: hormone; progestin;
Therapeutic: hormone; progestin
Prototype: Norgestrel
Pregnancy Category: X

Availability

0.35 mg, 5 mg tablets

Action

Synthetic progestational hormone with androgenic, anabolic, and estrogenic properties. Progestin-only contraceptives alter cervical mucus, exert progestational effect on endometrium, interfere with implantation, and, in some cases, suppress ovulation. May produce excess estrogenic effect.

Therapeutic Effect

Contraceptive that suppresses the midcycle surge of luteinizing hormone (LH).

Uses

Amenorrhea, abnormal uterine bleeding due to hormonal imbalance in absence of organic pathology; endometriosis. Also alone or in combination with an estrogen for birth control.

Contraindications

Thromboembolic disorders, cerebral vascular or coronary vascular disease; carcinoma of breast, endometrium, or liver; abnormal vaginal bleeding; known or suspected pregnancy (category X); children <16 y.

Cautious Use

Cardiac disease; history of depression, seizure disorders, migraine; diabetes mellitus; CHF; history of thrombophlebitis or thromboembolic disease.

Route & Dosage

Amenorrhea
Adult: PO Norethindrone 5–20 mg on day 5 through day 25 of menstrual cycle; Acetate 2.5–10 mg on day 5 through day 25 of menstrual cycle

Endometriosis
Adult: PO Norethindrone 10 mg/d for 2 wk; increase by 5 mg/d q2wk up to 30 mg/d, dose may remain at this level for 6–9 mo or until breakthrough bleeding; Acetate 5 mg/d for 2 wk, increase by 2.5 mg/d q2wk up to 15 mg/d, dose may remain at this level for 6–9 mo or until breakthrough bleeding

Progestin-Only Contraception
Adult: PO Norethindrone 0.35 mg/d starting on day 1 of menstrual flow, then continuing indefinitely

Administration

Oral

Note: Dosing schedule is based on a 28-d menstrual cycle.
Use or add a barrier contraceptive when starting the minipill regimen (progestin-only contraception) for the first cycle or for 3 wk to ensure full protection.
Protect drug from light and from freezing.

Adverse Effects (≥1%)

CNS: Cerebral thrombosis or hemorrhage, depression. CV: Hypertension, pulmonary embolism, edema. GI: Nausea, vomiting, cholestatic jaundice, abdominal cramps. Urogenital: Breakthrough bleeding, cervical erosion, changes in menstrual flow, dysmenorrhea, vaginal candidiasis. Other: Weight changes; breast tenderness, enlargement or secretion.

Interactions

Drug: barbiturates, carbamazepine, fosphenytoin, modafinil, phenytoin, primidone, pioglitazone, rifampin rifabutin, rifapentine, topiramate, troglitazone can decrease contraceptive effectiveness.

Pharmacokinetics

Absorption: Readily absorbed from GI tract. Metabolism: In liver. Elimination: In urine and feces as metabolites.

Nursing Implications

Assessment & Drug Effects

Monitor for S&S of thrombophlebitis (see Appendix F).
Withhold drug and notify physician if any of the following occur: Sudden, complete, or partial loss of vision, proptosis, diplopia, or migraine headache.

Patient & Family Education

Wait at least 3 mo before becoming pregnant after stopping the minipill to prevent birth defects. Use a barrier or nonhormonal method of contraception until pregnancy is desired.
If you have not taken all your pills and you miss a period, consider the possibility of pregnancy after 45 d from the last menstrual period; stop using progestin-only contraceptive until pregnancy is ruled out.
If you have taken all your pills and you miss 2 consecutive periods, rule out pregnancy and use a barrier or nonhormonal method of contraception before continuing the regimen.
Review package insert to ensure you understand how to use norethindrone.
Promptly report prolonged vaginal bleeding or amenorrhea.
Learn and do breast self-examination.
Keep appointments for physical checkups (q6–12mo) while you are taking hormonal birth control.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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