Flashcards in Contraception Deck (23):
What are sex hormones derived from and give examples.
All derived from cholestrol - oestrogen, oestradiol, oestriol, progesterone, testosterone (precursor - dihydrotestosterone).
Name 4 glycoprotein hormones and where they come from.
LH and FSH (hypothalamic GnRH to AP where LH/FSH is released to the ovaries/testes).
Human chorionic gonadotropin, hCG (from placenta)
Thyroid stimulating hormone - (from AP)
They all have alpha and beta chains. Alpha chains are common to all 4 but the beta chains provide specificity.
What is the consequence of pulsatile release of GnRH?
Release of LH and FSH.
What is the consequence of sustained release of GnRH?
Inhibit LH and FSH release.
What does LH do in the ovaries?
Acts on thecal cells in ovary to convert cholestrol to androgens.
What does FSH do in the ovaries?
Acts on granulosa cells to convert androgens to oestrogen.
When does oestrogen provide positive feedback - and what are the consequences of this?
Mid cycle, oestrogen provides positive feedback on the gonadotrophs to increase sensitivity to GnRH. This causes an LH surge causing ovulation.
What happens to temperature during ovulation?
It increases by 0.5 degrees.
Explain how steroids act at receptors and the consequences of this.
1) Steroid binds
2) Heatshock 90 protein is released revealing the DNA binding domain.
3) This acts with the transcription activating domain and binds DNA
4) Acts in dimers and bind the hormone responsive element of DNA.
5) Alters the transcription of specific genes.
Slow onset (3-4hrs) with a long duration.
Explain the Combined contraceptive pill.
Oestrogen and progesterone.
21 days pill, 7 days pill free.
Normal menstruation usually starts fairly quickly after cessation.
Effectiveness decreased by drugs that induce liver enzymes, and some antibiotics.
Explain how oestrogen and progesterone in the COC work.
Oestrogen inhibits FSH secretion.
- suppresses ovarian follicular development.
Progesterone inhibits LH secretion.
- prevents ovulation, makes cervical mucus hostile to sperm.
Oestrogen and progesterone...alter endometrium to discourage implantation.
What synthetic forms of oestrogen are used in the COC?
Ethinylestradiol (20-40 micrograms)
What syntheticforms of progesterone are used in the COC?
3/4gen have less effects on lipid levels but increase the risk of thrombosis.
Side effects of the COC?
Amenorhea on cessation.
Increased risk of thromboemboli
Advantages to the COC?
Decrease menstrual problems
decrease iron deficiency and anaemia.
decrease risk of benign breast cancer
decrease incidence of ovarian cysts
Explain the difference between mono,bi and tri phasic COC.
Monophasic - fixed oestrogen and progesterone.
Biphasic - 1 or 2 doses of oestrogen and 2 differernt doses of progesterone.
Triphasic - 1-2 doses of oestrogen, 3 different doses of progesterone.
Explain the combined contraceptive patch.
Ethinylestradiol and norelegestromin.
Each patch for 7 days x3 and then 1 7 days free.
Explain the vaginal ring.
Ethinylestradiol and etongestrel.
Apply for 21 days, 7 days free.
Explain the progesterone only pill.
Progesterone (any of the generations)
Inhibit LH secretion
Hostile cervical mucus.
Suitable even if increased risk of thromboembolism, smokers, old people etc.
BUT - irregular bleeding, decreased effectiveness by drugs that induce liver enzymes or some antibiotics.
Explain postcoital contraception.
levonorgestrel - up to 72 hours after intercourse. (one of 2 steps!)
Ulipristal - up to 5 days after intercourse.
(Selective progesteron receptor modulator).
Explain the intrauterine device.
Works for up to 5 days (120 hrs)
Copper containing device which interferes with implantation - hostile environment for sperm.
Give 2 examples of long acting contraceptives.
EG seasonal......84 days active pill, 7 day placebo - 4 periods per year.
Lybrel - active pill every day - no periods!