Hormonal Contraceptives

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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. Hormonal Contraceptives and HPO Axis

⭐ 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.

Combined Oral Contraceptives by Generation

⭐ 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. Progestogen-Only Contraception Types and Administration

⭐ 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.

Practice Questions: Hormonal Contraceptives

Test your understanding with these related questions

A 28-year-old nonsmoking woman presents to discuss birth control methods. She requests a contraceptive option that is not associated with weight gain. She and her husband agree that they desire no children for the next few years. Her periods are regular, but heavy and painful, with severe lower abdominal cramping and back pain, requiring pad changes every 4 hours. This pattern of bleeding has been present since she was 15 years old. For a week before her period begins, she experiences uncharacteristic tearfulness, irritability, and depression, which are affecting her personal relationships. Her physical examination reveals blood pressure 110/75, BMI 22, and moderate acne on her face and neck. What recommendation would best address her mood, skin, and contraceptive needs?

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Flashcards: Hormonal Contraceptives

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_____ is a selective progesterone receptor modulator (SPRM) that acts as an emergency contraceptive by inhibiting ovulation by inhibiting LH surge

TAP TO REVEAL ANSWER

_____ is a selective progesterone receptor modulator (SPRM) that acts as an emergency contraceptive by inhibiting ovulation by inhibiting LH surge

Ulipristal

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