COCs: Basics & MOA - Pill Power Intro
Combined Oral Contraceptives (COCs) are widely used hormonal pills containing synthetic estrogen and progestin. They offer highly effective, reversible contraception when used correctly.
- Core Mechanism of Action (MOA):
- Ovulation Inhibition (Primary): Estrogen suppresses FSH (ā follicle development); Progestin suppresses LH surge (prevents ovulation). Both act on hypothalamus-pituitary-ovarian axis.
- Cervical Mucus Thickening: Progestin makes mucus viscous, ā impenetrability to sperm.
- Endometrial Alteration: Endometrium becomes thin, atrophic, and unreceptive to blastocyst implantation.
- Estrogen Component: Typically Ethinyl Estradiol (EE), common doses range 20-35 µg.

ā Ethinyl estradiol (EE) is the most common synthetic estrogen in COCs; newer COCs may use estradiol valerate or estetrol (E4).
COCs: Benefits, Risks & Combined Methods - Perks, Perils, Combos
- Benefits (Non-Contraceptive):
- Significant ā Ovarian & Endometrial cancer risk.
ā Combined hormonal contraceptives significantly reduce the risk of ovarian and endometrial cancers.
- Menstrual cycle regulation: ādysmenorrhea, āmenorrhagia.
- Other: āPelvic Inflammatory Disease (PID), āectopic pregnancy, ābenign breast disease, āacne, āhirsutism.
- Significant ā Ovarian & Endometrial cancer risk.
- Risks & Contraindications (CI):
- VTE (Venous Thromboembolism): Estrogen-dependent; highest risk in 1st year.
- Cardiovascular: āMI/Stroke (CI: smokers >35yrs, uncontrolled HTN, migraine with aura).
- HTN, Gallbladder disease, Hepatic adenoma (rare).
- Cancer: Slight āBreast Ca risk (normalizes 10 yrs post-cessation); āCervical Ca risk with >5 yrs use.
- Other Combined Hormonal Methods:
- Transdermal Patch (e.g., Evra): Weekly; higher systemic estrogen exposure.
- Vaginal Ring (e.g., NuvaRing): Monthly; lower systemic estrogen.
- Missed COC Pill Management:
Progestin-Only Contraceptives - Solo Hormone Hits
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Mechanism: Thicken cervical mucus, suppress ovulation (variably), endometrial changes.
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Ideal for: Breastfeeding, estrogen contraindications (e.g., VTE risk, smokers >35 yrs, migraine with aura).
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Types:
- Progestin-Only Pills (POPs / Mini-pills):
- E.g., Norethindrone, Levonorgestrel.
- Strict 3-hour intake window (traditional); 12-hour for desogestrel. š POP In Time!
- Common: Irregular bleeding.
- Injectables (DMPA):
- Depot Medroxyprogesterone Acetate: 150 mg IM / 104 mg SC every 3 months.
- Side effects: Menstrual changes (amenorrhea common), weight gain.
- Delayed fertility return (~9-10 months).
- ā > DMPA (Depo-Provera) use is associated with a potential reversible decrease in bone mineral density, particularly with long-term use.
- Implants (e.g., Etonogestrel - Nexplanon):
- Long-acting (up to 3 years).
- Highly effective.
- Common: Irregular bleeding.

- Progestin-Only Pills (POPs / Mini-pills):
Emergency Contraception & Comparisons - Backup & Best Bets
- Top ECP Choices (Post-Coitus):
- Copper IUD (Cu-IUD): Most effective, up to 120 hrs.
- Ulipristal Acetate (UPA): 30mg dose, up to 120 hrs.
- Levonorgestrel (LNG): 1.5mg dose, up to 72 hrs (some efficacy up to 120 hrs).
- Mechanisms:
- UPA/LNG: Primarily delay/inhibit ovulation.
- Cu-IUD: Prevents fertilization; inhibits implantation.
- Key Note: High BMI may ā hormonal ECP efficacy; Cu-IUD often preferred.
ā Ulipristal acetate (UPA) is more effective than Levonorgestrel for emergency contraception, especially closer to ovulation and up to 120 hours post-coitus.
HighāYield Points - ā” Biggest Takeaways
- OCPs primarily inhibit ovulation; progestins thicken cervical mucus & alter endometrium.
- Combined OCPs ā risk of ovarian & endometrial cancer, regulate cycles, and improve acne.
- Progestin-only pills (POPs) are preferred during lactation & for women with estrogen contraindications (e.g., VTE history).
- Emergency Contraception: Levonorgestrel (LNG) within 72 hours, Ulipristal acetate (UPA) within 120 hours; Copper IUD is most effective.
- Absolute COCP Contraindications: History of VTE, stroke, migraine with aura, current breast cancer, severe liver disease, uncontrolled hypertension.
- DMPA (injectable): Associated with delayed return to fertility and potential ā bone mineral density with long-term use.
- Hormonal IUDs (LNG-IUS): Provide long-acting reversible contraception and can significantly reduce menstrual bleeding, treating menorrhagia.
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