6. Drugs affecting reproductive function Flashcards
Where are oestrogens synthesised?
Ovary and the placenta
Small amounts in adrenal cortex and testis
Clinical uses of oestrogens?
- Induce artificial menstrual cycle
- Contraception
- At or after menopause to prevent symptoms e.g. protect against osteoporosis, vaginal dryness and flushing
- Replacement therapy in primary ovarian failure (Turner’s syndrome) to promote sexual maturation
- Prostate and breast cancer
Side effect: Increase risk of thromboembolism, cause feminisation in Males
Oestrogen administration options?
Preparations: Oral, transdermal, intramuscular, implantable, topical (as it is well absorbed across the gut, skin and mucous membranes)
Options:
Natural e.g. Estragiol, estriol
Synthetic e.g. Menstranol, ethinylestradiol, diethylstilbestrol
Binding of eostrogens in the blood?
To albumin and to a sex hormone-binding globulin.
Thus making the oestrogens inactive
What does SERMs mean?
Selective Oestrogen Receptor Modulators
What are SERMs?
Competitive antagonists or partial agonists of oestrogens
3 examples of SERMs
Clomiphene
Tamoxifen
Raloxifene
Action of clomiphene?
Acts as an oestrogen antagonist in the hypothalmus and anterior pituitary to inhibit the negative feedback to induce ovulation.
Action of taxoxifen?
One such drug used in estrogen-dependent breast cancer. (anti-estrogenic action on mammary tissue)
Acton of raloxifene?
Used to treat and prevent osteoporosis (estrogenic action on bone).
3 oestrogens in the body are
Oestradiol **
Oestrone
Oestriol
Progesterone secreted by..
Corpus luteum in mentrual cycle follicular phase
Placenta during pregnancy
Relationship between progesterone, PR and oestrogen?
Progesterone acts on the PR (progesterone receptor) to regulate gene transcription in target tissues.
Oestrogen stimulates PR synthesis.
Progesterone inhibits oestrogen receptor synthesis
What are progestins?
Synthetic derivatives of progesterone (as progesterone is cleared rapidly so not used therapeutically)
3 examples of progestins?
Medroxyprogesterone
Hydroxyprogesterone
Norethisterone
Therapeutic uses for progestogens?
- Oral contraceptive pill alone or in combination with estrogen **
- Used as progesterone only injectable/ implantable contraception or as part of an intrauterine contraceptive.
- Combined with estrogen for estrogen replacement therapy in women, with an intact uterus, to prevent:
– endometrial hyperplasia
– carcinoma
– endometriosis