Oral Contraceptives Flashcards
What is the mechanism of action of the combined oral contracpetive pill?
the synthetic oestrogen acts to provide negative feedback to the hypothalamus and anterior pituitary to block the release of GnRH and FSH (and sometimes LH) to prevent ovulation, the synthetic progesterone sometimes inhibits LH release but also stops endometrium proliferation, makes the mucous inhospitable for sperm and interferes with the contraction of the fallopian tubes and uterus
What is the most commonly used synthetic oestrogen?
ethinyloestradiol
What is levonorgestrel?
a progestogen - older type which is slightly androgenic
What is cyproterone?
a progestogen - a newer type which is not androgenic so is better for PCOS
What is drospirenone?
an aldosterone antagonist used in combination with a synthetic oestrogen in newer COCs (yasmin)
What are the side effects of levonorgestrel?
hirsuitism, acne
What is the combined oral contraceptive pill?
a combination of a synthetic oestrogen and a progestogen in a fixed ratio of 21 active pills and 7 sugar pills per cycle
What is a sequential preparation?
a pill with different doses of oestrogen and progestogen to mimic the endogenous changes
What is the progestogen only oral contraceptive?
the mini pill - only contains progestogen and no oestrogen - used in women when oestrogen is contraindicated and when lactating because doesnt inhibit prolactin
What are the side effects of the COCs?
hypertension, venous thromboembolism, increased risk of breast, cervical and uterine cancer (excpet progestogen negates the risk of uterine cancer), and other (fatigue, headaches, weight gain, nausea etc.)
What are the benefits of COCs?
decreased risk of endometrial cancer (if have progestegin), decreased risk of ovarian cancer and ovarian cyst formation, reduction in risk of colorectal cancer, protective effect on benign breast tumours, reduction in risk of bone fractures, reduction in dysmenorrhoea and menorrhagia
What is the morning after pill?
1500micrograms of levonorgestrel 72 hours after unprotected sex - stops implantation
Which COCs have the highest risk of venous thromboembolism?
COCs containing newer progestogens particularly cyproterone
Which women are particular at risk of venous thromboembolism when on the pill?
women over 35 who smoke
