Paper II
2021 December (Supplementary) (2010 Scheme)

Question

What are the different types of oral contraceptive pills available. Describe the mechanism of action and adverse effects of combined oral contraceptive pills.(2+2+2)

Q26 marksEssays

Answer

Types of oral contraceptive pills

  • Combined oral contraceptive pills (oestrogen + progestin) — monophasic, biphasic, triphasic
  • Progestin-only pills (“mini-pill”)
  • Emergency contraceptive pills (high-dose levonorgestrel)
  • Centchroman (non-steroidal SERM-based, weekly pill)

Mechanism of action of combined OCPs

  • Oestrogen suppresses FSH secretion (inhibits follicular development) and stabilizes the endometrium
  • Progestin suppresses LH secretion (inhibits ovulation), thickens cervical mucus (impairs sperm penetration), and makes the endometrium unfavourable for implantation
  • Together, they reliably suppress the hypothalamic-pituitary-ovarian axis, preventing ovulation

Adverse effects

  • Thromboembolism (DVT/PE)
  • Increased risk of MI/stroke (especially smokers >35 years, hypertensives)
  • Hypertension
  • Hepatic adenoma/cholestatic jaundice
  • Gallstones
  • Breakthrough bleeding, weight gain, mood changes
  • Small increased risk of breast/cervical cancer (with reduced risk of ovarian/endometrial cancer)

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