Dosing and uses of Aygestin, Norlutate (norethindrone acetate)
Adult dosage forms and strengths
tablet
- 5mg
Amenorrhea or Uterine Bleeding
2.5-10 mg/day PO for 5-10 days during latter part of cycle
Expect withdrawal bleeding within 3-7 days after stopping norethindrone
Endometriosis
5 mg PO qDay for 14 days, may increase by 2.5 mg up to 15 mg/day PO for 6-9 months
Pediatric dosage forms and strengths
Pre-menarche: Not recommended
Aygestin, Norlutate (norethindrone acetate) adverse (side) effects
Frequency not defined
Edema
Weakness
Anorexia
Amenorrhea
Breakthrough bleeding
Change in menstrual flow
Spotting
Deep vein thrombosis
Thrombophlebitis
Depression
Dizziness
Headache
Nervousness
Somnolence
Breast tenderness
Galactorrhea
Abdominal pain
Nausea
Vomiting
Weight change
Cholestatic jaundice
Warnings
Contraindications
Documented hypersensitivity
Estrogen-dependent neoplasia
Arterial thromboembolic disease (stroke, MI), thrombophlebitis, DVT/PE, thrombogenic valvular disease, cerebral apoplexy
Estrogen-dependent neoplasia, liver disease, liver tumors
Undiagnosed abnormal vaginal bleeding
Diabetes mellitus with vascular involvement
Jaundice with prior oral contraceptive use
Missed abortion or as diagnostic test for pregnancy
Cautions
Norethindrone acetate is 2 times as potent as norethindrone
Family history of breast cancer and or DVT/PE, current/history of depression, endometriosis, DM, HTN, bone mineral density changes, renal/hepatic impairment, bone metabolic disease, SLE; conditions exacerbated by fluid retention (eg, migraine, asthma, epilepsy).
Discontinue if the following develop jaundice, visual problems (may cause contact lens intolerance), any signs of VTE, migraine with unusual severity, significang blood pressure increase, severe depression, increased risk of thromboembolic complications after surgery.
Rare hepatic adenomas and focal modular hyperplasia, resulting in fatal intra-abdominal hemorrhage reported with therapy
Irregular menstrual bleeding is common with progestin only contraceptives; rule out nonpharmacologic causes of abnormal bleeding
Not for use prior to menarche
Discontinue 4 week before major surgery or prolonged immobilization. Patients on warfarin, oral anticoagulants (increase in anticoagulant dose may be warranted).
Some studies link OCP use with increased risk of breast cancer, whereas other studies have not shown a change in risk. Woman's risk depends on conditions where naturally high hormone levels persist for long periods of time including early onset menstruation before age 12, late onset menopause, after age 55, first child after age 30, nulliparity.
Increased risk of cervical cancer with OCP use, however HPV remains as main risk factor for this cancer. Evidence suggests long-term use of OCPs, 5 or more years, may be associated with increased risk. Increased risk of liver cancer with OCP use; risk increases with longer duration of OCP use.
Pregnancy and lactation
Pregnancy category: X
Lactation: Excreted in breast milk; use caution
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Aygestin, Norlutate (norethindrone acetate)
Mechanism of action
Progestin; inhibits secretion of gonadotropins from pituitary gland; prevents follicular maturation & ovulation, stimulates growth of mammary tissues
Absorption
Bioavailability: 64%
Peak Plasma Time: 1-2 hr
Distribution
Vd: 4 L/kg
Protein Bound: 61%
Metabolism
Liver
Metabolites: Sulfate and glucuronide metabolites (inactive)
Elimination
Half-Life: 4-13 hr
Excretion: Urine 33-81%; feces 35-43%
