(3.1) Reproductive Hormone Pharmacology

Question 1

Describe the mechanisms of the types of oral contraceptive methods.

Answer 1

Combined Oral Contraceptive Pill

• [Oestrogen]high -> -ve feedback -> prevent LH surge -> no ovulation
• [Progesterone]high -> enhances -ve feedback
• [Progesterone]high -> thick & acidic cervical mucus

Progesterone Only Pill
- [Progesterone]high -> thick & acidic cervical mucus

Question 2

Compare and contrast the pros and cons of using COCP and POP, e.g. groups of patients who benefited and who should be avoided.

Answer 2

• COCP often preferred: Progesterone prevents unopposed Oestrogen action of continuous stimulation on endometrial thickening e.g. protecting from Endometrial Cancer
• POP is preferred in patients with CVD and smokers: Oestrogen affects coagulants -> increases risk of thromboembolism
• POP preferred in breast feeding mother: Oestrogen inhibits Prolactin production
• POP is preferred in hypertensive patient: both Oestrogen & Progesterone increases blood pressure -> COCP doubling the effects
• POP Con: is less reliable, more side effects and gives irregular menstrual cycles

Question 3

Suggest some side effects of Progesterone Only Pill.

Answer 3

• Amenorrhoea
• Breast tenderness (mastalgia)
• Mood swings

Question 4

Suggest some side effects of COCP.

Answer 4

• Weight gain
• Thromboembolism
• Hypertension
• Gallstones

Question 5

Suggest some risks of Hormone Replacement Therapy.

Answer 5

• Break cancer
• Ovarian/Endometrial Cancer
• Stroke / DVT

Question 6

What is Clomiphene and how does it work?

Answer 6

• Pituitary Oestrogen Antagonist

- Inhibits -ve feedback -> LH surge -> induces ovulation

Question 7

Suggest the uses of Raloxifene and how does it work?

Answer 7

• To post-menopausal women
• Breast Oestrogen Antagonist -> reduces risk of breast cancer
• Bone Oestrogen Agonist -> reduces risk of Osteoporosis

Question 8

Suggest a use of Tamoxifen and a risk of it.

Answer 8

• Breast Oestrogen Antagonist -> treat Breast Cancer

- Endometrial Oestrogen Agonist -> risk of Endometrial Cancer

Question 9

Suggest two used of Anti-progesterone (mifepristone).

Answer 9

• Induction of labour (initiated by a drop of Progesterone:Oestrogen ratio)
• Termination of pregnancy in 1st Trimester (given with Prostaglandin)

Question 10

A 27 years old woman whose taking contraceptive pills, but now she has been prescribed a board spectrum antibiotic due to an infection. Would you be concern about the drug interactions?

Answer 10

If she was on COCP, its effectiveness may be reduced because Oestrogen undergoes entero-hepatic metabolism:

• some antibiotics are CYP450 inducer -> reduced half life -> less active time
• antibiotics disturb normal gut flora -> reduced reuptake -> faster elimination into faeces