L20 PHRM20001 - Contraceptives

Question 1

Where is Oestrogen and where is progesterone released?

Answer 1

Oestradiol/Oestrogen- ovaries, placenta (once conception and implantation has occurred), testes

Progesterone – ovaries, adrenal cortex

Question 2

Synthetic compared to natural?

Answer 2

Synthetic oestrogen have a higher bioavailability as they go through the enterohepatic circulation and keep getting released again where else the natural go through first pass metabolism

Question 3

Precursor for progesterone, testosterone, oestradiol?

Answer 3

Cholesterol

Question 4

Examples of synthetic oestrogen (1)

Answer 4

Oestrogens – ethinyloestradiol (synthetic), -ve feedback

Question 5

Examples of synthetic progestogens (2)

Answer 5

Levonorgestrel (pure substance used in morning after pill), drospirenone (relatively new, slight diuretic activity so women lose weight on the pill and anti-androgenic), changes cervical mucous to make it hostile to sperm so it cannot penetrate, changes endometrium and makes it harder to implant, reduces motility of sperm in fallopian tube

Question 6

3 types of contraceptive in order of efficacy

Answer 6

1. Combined preparations (COCs) -
   Mixture of oestrogen and progestogen in a fixed ratio of doses.
2. Sequential preparations-
   Ratio of doses varies to correspond approximately to changes in endogenous oestrogen and progestogen.
3. Progestogen-only oral preparations (Mini-pill) -
   When oestrogens are contraindicated (there are reasons not to use it) – least effective of OCs, may be used by lactating women as it blocks prolactin from anterior pituitary for lactation.

Question 7

4 adverse effects of COCs

Answer 7

Hypertension, Venous thromboembolism, cancer, other (Nausea/vomiting, Dizziness, Flushing, Breast discomfort, Headache, Decreased libido, Chloasma (pigmentation), Acne, Depression, Irritability, Fatigue )

Question 8

Benefits of COCs

Answer 8

• Decreased risk of endometrial cancer (due to progesterone)
• Decreased incidence of ovarian cancer and ovarian cyst formation
• Reduction in risk of colorectal cancer , bone fractures, dysmenorrhoea (painful period) and menorrhagia (heavy bleeding and therefore protection against iron deficiency anaemia)
• Protective effect on benign breast tumours

Question 9

3 other forms of contraceptions besides oral

Answer 9

1. Vaginal Ring
   • NUVARING® – etonogestrel and ethinyloestradiol. It is inserted into the vagina, left for three weeks and removed for one week. The process is repeated. It is effective with lower doses of hormones as it bypasses the portal circulation.
2. Progestogen-Only Contraceptives
   • MIRENA® – levonorgestrel, intrauterine device, effective up to 5 years
3. Emergency Contraception (morning-after pill)
   • POSTINOR-1® – one tablet of 1500g levonorgestrel, within 72hrs after unprotected intercourse