What are the guidelines for using Loestrin 1/21 (Ethinyl Estradiol and Norethindrone)?

Guidelines for Using Loestrin 1/21 (Ethinyl Estradiol and Norethindrone)

Loestrin 1/21 is an effective combined oral contraceptive containing 1 mg norethindrone acetate and 20 mcg ethinyl estradiol that should be taken daily for 21 consecutive days followed by 7 pill-free days to prevent pregnancy and manage certain hormonal conditions.

Indications and Efficacy

• Primary indication: Contraception (approximately 9 out of 100 women become pregnant in the first year with typical use of combined hormonal contraceptives) 1
• Secondary indications:
  • Management of acne vulgaris 1
  • Treatment of menorrhagia (can reduce menstrual blood loss by up to 50%) 2
  • Normalization of testosterone levels in women with polycystic ovary syndrome 3

Dosing Instructions

• Take 1 pill daily at the same time for 21 consecutive days
• Follow with 7 pill-free days (during which withdrawal bleeding typically occurs)
• Begin therapy either on the first day of menstrual period or on the first Sunday after onset of menstruation 1
• May be initiated 4 weeks postpartum in non-lactating mothers 1

Initiation Guidelines

Starting Loestrin 1/21:

• First 5 days since menstrual bleeding started: No additional contraceptive protection needed
• >5 days since menstrual bleeding started: Use additional contraceptive protection (e.g., condoms) for the next 7 days 1

Special Populations:

1. Amenorrhea (Not Postpartum):

   • Can start at any time if reasonably certain woman is not pregnant
   • Use additional contraceptive protection for the next 7 days 1

2. Postpartum (Breastfeeding):

   • Should not use during first 3 weeks after delivery (U.S. MEC 4)
   • Generally should not use during fourth week postpartum (U.S. MEC 3)
   • If ≥21 days postpartum and menstrual cycles have not returned, use additional contraceptive protection for 7 days 1

3. Postpartum (Not Breastfeeding):

   • Should not use during first 3 weeks after delivery (U.S. MEC 4)
   • If ≥21 days postpartum, use additional contraceptive protection for 7 days 1

4. Post-abortion:

   • Can start within first 7 days after first or second trimester abortion
   • May require additional contraceptive protection 1

Management of Missed Pills

If ONE pill is missed:

• Take the missed pill as soon as possible
• Continue taking remaining pills at usual time
• No additional contraceptive protection needed 1

If TWO or more pills are missed:

• Take the most recent missed pill as soon as possible (discard other missed pills)
• Continue taking remaining pills at usual time
• Use backup contraception for 7 consecutive days
• If pills were missed in the last week (days 15-21):
  • Omit the hormone-free interval
  • Start a new pack immediately 1
• Consider emergency contraception if pills were missed during the first week and unprotected intercourse occurred in previous 5 days 1

Vomiting or Severe Diarrhea

• If vomiting occurs within 3-4 hours of taking a pill, consider it a missed pill
• Follow missed pill guidelines
• If severe diarrhea continues for >24 hours, follow missed pill guidelines 1

Contraindications

Loestrin 1/21 should NOT be used in women with:

• Active or history of arterial thromboembolic disease (stroke or myocardial infarction)
• Breast cancer or other estrogen/progestin-sensitive cancer
• Deep vein thrombosis or pulmonary embolism (current or history)
• Uncontrolled hypertension
• Migraine with aura if >35 years of age
• Smoking if >35 years of age
• Hepatic tumors (benign or malignant) or active liver disease
• Undiagnosed genital bleeding
• Pregnancy 1

Common Adverse Effects

• Headache, depression, or mood changes
• Breast pain, irregular menstruation, or weight changes
• Nausea, vomiting, abdominal pain
• Breakthrough bleeding (particularly in first 3 months)
• Amenorrhea 1

Drug Interactions

Loestrin 1/21 effectiveness may be reduced by:

• Antibiotics (rifampin, griseofulvin)
• Anticonvulsants (phenytoin, carbamazepine, topiramate, barbiturates)
• St. John's Wort
• HIV protease inhibitors
• Other medications that induce liver enzymes 1, 2

Monitoring

• Baseline: Pregnancy status, blood pressure
• Ongoing: Blood pressure, monitor for health status changes 1

Special Considerations

• Breastfeeding: World Health Organization recommends avoiding if possible; infant risk cannot be ruled out 1
• Return to fertility: Fertility returns quickly after discontinuation 2
• STI protection: Does not protect against sexually transmitted infections; condoms recommended if STI protection is needed 1
• Breakthrough bleeding: More common in first 3 months of use; typically improves with continued use 2
• Cycle control: Studies show Loestrin 1/21 may have higher rates of breakthrough bleeding compared to some other formulations 4

Alternative Formulations

• Loestrin 24 Fe: A 24-day regimen of the same hormones (NETA 1 mg/EE 20 mcg) that may provide better cycle control with fewer intracyclic bleeding days and fewer total bleeding/spotting days 5