Hormonal Contraceptives

Hormonal Contraceptives - How They Work

• Central Action (Ovulation Inhibition):
  • Estrogen: Suppresses FSH release from pituitary → ↓ follicular development. Stabilizes endometrium.
  • Progestin: Suppresses LH surge (primary contraceptive effect) → prevents ovulation.
• Peripheral Actions (Mainly Progestin):
  • Cervical mucus: Thickens → impedes sperm penetration.
  • Endometrium: Becomes unreceptive/atrophic → hinders implantation.
  • Fallopian tubes: Altered motility → ↓ gamete/zygote transport.

⭐ Progestin is the key contraceptive driver by inhibiting the LH surge; estrogen supports by suppressing FSH and providing cycle stability.

Hormonal Contraceptives - Estrogen + Progestin Power

Combined Hormonal Contraceptives (CHCs) contain Estrogen (Ethinyl Estradiol) + Progestin.

• Mechanism of Action:
  • Estrogen: Suppresses Follicle Stimulating Hormone (FSH) → inhibits follicular development.
  • Progestin: Suppresses Luteinizing Hormone (LH) surge → inhibits ovulation; thickens cervical mucus; creates atrophic endometrium (hostile to implantation).
• Forms: Oral pills (monophasic, biphasic, triphasic), transdermal patch, vaginal ring.
• Non-Contraceptive Benefits:
  • ↓ Risk of ovarian & endometrial cancer.
  • ↓ Benign breast disease, Pelvic Inflammatory Disease (PID), ectopic pregnancy.
  • Regularizes menses; ↓ dysmenorrhea, menorrhagia.
  • Improves acne & hirsutism.
• Key Adverse Effects & Risks:
  • Estrogen-related: Nausea, breast tenderness, headache, Venous Thromboembolism (VTE), Hypertension (HTN), Myocardial Infarction (MI)/Stroke (risk ↑ in smokers >35 yrs).
  • Progestin-related: Mood changes, weight gain, acne, breakthrough bleeding.
• Absolute Contraindications:
  • History of VTE, CAD, CVA, known thrombogenic mutations.
  • Migraine with aura.
  • Breast cancer (current or past).
  • Severe liver disease/tumor.
  • Uncontrolled HTN (>160/100 mmHg).
  • Smokers >35 years (≥15 cigarettes/day).
  • Known pregnancy.

⭐ CHCs significantly reduce the lifetime risk of developing ovarian and endometrial cancers by up to 50% after several years of use, with protection persisting after discontinuation.

Hormonal Contraceptives - Progestin-Only Players

• Progestin-Only Pills (POPs / Minipills)
  • Mechanism: Thicken cervical mucus, endometrial atrophy, inconsistent ovulation inhibition.
  • Examples: Norethindrone, Levonorgestrel. Strict 3-hour missed pill window.
  • Ideal for: Breastfeeding, estrogen contraindications (e.g., VTE history, migraine with aura, smoker >35 years).
  • Side effect: Irregular bleeding.
• Injectable Progestins
  • Depot Medroxyprogesterone Acetate (DMPA): IM/SC every 3 months. Inhibits ovulation.
    • ⚠️ Delayed return to fertility (up to 10 months); reversible bone mineral density loss.
  • Norethisterone Enanthate (NET-EN): IM every 2 months.
• Implants
  • Etonogestrel (e.g., Nexplanon): Subdermal, lasts 3 years. Highly effective.
  • Side effect: Irregular bleeding patterns.
• Intrauterine Systems (IUS)
  • Levonorgestrel-IUS (LNG-IUS, e.g., Mirena): Lasts 5-8 years (device dependent).
  • Mechanism: Local progestogenic effect on endometrium & cervical mucus.
  • Benefits: Reduces menstrual bleeding/dysmenorrhea.

⭐ Progestin-only methods are a crucial alternative for women with contraindications to estrogen, such as those with a history of venous thromboembolism (VTE), certain cardiovascular diseases, or during lactation immediately postpartum (WHO MEC Category 1 or 2).

Hormonal Contraceptives - Emergency & Beyond

Emergency Contraception (EC):

COCs: Non-Contraceptive Benefits:

• ↓ Risk: Ovarian cancer (~50%), endometrial cancer (~70%), PID, ectopic, benign breast disease.
• Cycle: Regularizes, ↓ dysmenorrhea, ↓ menorrhagia.
• Improves: Acne, hirsutism.

Drug Interactions (↓ Efficacy):

• Enzyme inducers (CYP450): Rifampicin, phenytoin, carbamazepine, phenobarbital, St. John’s Wort.
• Broad-spectrum antibiotics (e.g., tetracyclines, ampicillin): Use backup during & 7 days after.

⭐ Ulipristal Acetate (UPA), a SPRM, is more effective than Levonorgestrel for EC, especially if taken 72-120 hours post-coitus.

High‑Yield Points - ⚡ Biggest Takeaways

• Combined OCPs primarily inhibit ovulation using estrogen (ethinylestradiol) and progestin.
• Key absolute contraindications: history of VTE, current breast cancer, active liver disease, uncontrolled hypertension, migraine with aura.
• Progestin-only pills (POPs) are preferred during lactation and when estrogen is contraindicated.
• Emergency contraception: Levonorgestrel (effective up to 72 hours), Ulipristal acetate (up to 120 hours).
• OCPs offer non-contraceptive benefits like reduced risk of ovarian and endometrial cancers.
• Enzyme inducers (e.g., rifampicin, phenytoin) significantly reduce OCP efficacy, risking failure.