S5.2 Sex Steroid Hormones Flashcards
(19 cards)
What are the effects of oestrogen?
Stimulates growth of the endometrium and breast
What are the actions and ADRs of oestrogen?
Na and water retention, decrease bone resorption
ADRs: breast tenderness, nausea
What are the effects of progesterone?
Stimulates growth of the endometrium and breast; maintains pregnancy and prepares endometrium for implantation
What are the actions and ADRs of progesterone?
Increases bone density
ADRs: weight gain, acne
What are the effects of testosterone?
Stimulates male characteristics e.g pubes, deep voice
What are the ADRs of testosterone?
Acne, aggression
Describe the transport of sex steroid hormones
Transport bound to SHBG (sex hormone binding globule, production upregulated by oestrogen) and albumin
Describe the pharmacokinetics of sex steroid hormones
Liver metabolism: hormones metabolised in one passage through liver.
Stored in fatty tissue which increases half life
What is the mechanism of the OCP?
Oestrogen (ethinyloestradiol) + progesterone (levonorgestrel). Prevents ovulation (inhibits FSH LH), thickening of cervical mucous
What are the ADRs of the OCP?
Venous thromboembolism, MI, Hypertension.
Metabolised by CP450, so there efficacy is reduced by enzyme inducing drugs;
Phenytoin, Carbamazapine, Rifampicin, Rifabutin (as all increase CP450)
Describe the features of the progesterone-only pill
E.g: levonorgestrel, norethisterone, medroxyprogesterone.
Thickens cervical mucus so impenetrable to sperm.
ADRs: menstrual problems common
What advice would you give to a woman who missed the pill on one day?
Take last pill immediately and continue others as normal. May need extra contraception for next 7 days.
What are the two forms of emergency contraception?
Levonorgestrel (72h after sex), ulipristal acetate (120h after sex).
Describe the two types of HRT
Unopposed oestrogen (E)RT - risk of endometrial or ovarian cancer. Opposed oestrogen (H)RT - risk of breast cancer. Both reduce menopausal symptoms, and can increase HDL
What is the mechanism of clomiphene?
Ovulation induction: inhibits oestrogen to its receptor in the anterior pituitary, inhibits negative feedback, so results in increased FSH, LH expression
What is the mechanism of tamoxifen?
Reduces risk of breast cancer: Binds to oestrogen receptor in breast tissue and blocks oestrogen-stimulated myoepithelial cell division
What is the mechanism of anti-progestins (mifepristone)?
Inhibits progesterone action.
Sensitises the uterus to prostaglandins, is used for termination of pregnancy and induction of labour
What is the mechanism of anti-androgens (cyproterone)?
Partial agonist at progesterone receptor, that competes with DHT. Used to treat prostate cancer.
What is the mechanism of the SERM raloxifene?
Protects against osteoporosis.
Reduced risk of invasive breast cancer in postmenopausal women with osteoporosis
