B.15 Flashcards
Estrogens and antiestrogens
- Estrogen analogs: Ethinylestrogen, Estradiol
- SERM: Tamoxifene, Raloxifene, Clomifene
- Affecting GnRH: Goserelin, Degarelix
- Aromatase inhibitor: Anastrozole
SERM
Selective Estrogen Receptor Modulator
Palliative treatment
Medical care given to relieve the symptoms and improve the quality of life of patients with advanced or terminal cancer. This treatment doesn’t cure the cancer, but rather provide confort and support to the patient.
Ethinylestradiol
MOA: synthetic Estrogen analog (binds estrogen receptor and activates it)→ ↓LH→↓endometrial vascularizaiton. ↓GnRH→prevent ovulation.
It also ↑SHBG;
IND: Combined with other drugs for contraceptive, premenstrual dysphoric disorder, moderate acne, prevention of postmenopausal osteoporosis;
Kinetics: can be adm. s.c, as contraceptive patch, locally as vaginal ring (3week use-1 week pause), ↑PPB, metabolized in the liver, excreted in bile/urine/feces; has a long T1/2;
SEs: headache, dizziness, weight gain, impaired glucose tolerance, abnormal bleeding
Estradiol
MOA: Estrogen analog (binds estrogen receptor and activates it)→acts on vasomotor systems (such as hot flashes) and urogenital symptoms (such as vaginal dryness), inhibits bone resorption, have beneficial effect on plasma lipid profile;
IND: treatment of moderate-severe vasomotor symptoms and vulvar and vaginal atrophy due to menopause, hypoestrogenism due to hypogonadism /casteration /primary ovarian failue, prevention of postmenopausal osteoporsis, treatment of breast cc (only for Palliative treatment), treatment of androgen dependent prostate cc, in combination with other drugs as oral contraceptive pills
Clomifene
MOA: SERM, mechanism not completely understood (somehow it stimulates the release of GnRH, FSH and LH→ development and maturation of follicle→ovulation→development & function of the corpus luteum→pregnancy);
IND: Ovulation-inducing agent (e.g. in patients with anovulation→PCOS);
Kinetics: p.o adm., good absorption, hepatic metabolism, excreted mainly via feces, long T1/2
Tamoxifene
MOA: SERM (→competitively inhibits estrogen binding to its receptor→ inhibiting growth and promotes apoptosis in estrogen-R positive tumors), it also ↑SHBG (→↓the amount of freely available estradiol);
IND: Used in palliative treatment of estrogen-R positive breast cc in postmenopausal women;
Kinetics: has narrow therapeutic index (can lead to breathing diffculty or convulsions),
Raloxifene
MOA: SERM (exhibits estrogenic effects on bone&lipid metabolism, and antiestrogenic effects on uterine endometrium and breast tissues)→inhibits bone resorption, ↑bone mineral density;
IND: Prevention&treatment of post-menopausal osteoporosis, prevention &treatment of corticosteroid-induced bone loss, reduction in the risk of invasive breast cc in postmenopausal women with osteoporosis/women with high risk for invasive breast cc;
Kinetics: good p.o abs., ↑PPB, metabolized in liver and intestines, mostly fecal elimination
Anastrozole
MOA: non-steroidal Aromatase inhibitor;
IND: breast cc resistant to Tamoxifen
Goserelin
MOA: GnRH analogs (binds GnRH-R on the pituitary gonadotrophs and stimulate release of FSH and LH); IND: Hormone-dependent tumors (prostate, breast), Endometriosis, preterm puberty, Assisted fertillization (→stopping the pituitary function during preparation), Diagnostics (LH. FSH producing capacity), Hormone replacement (pulsatile→ hypothalamic hypogonadism, Kallmann sy.);
SEs: at the beginning of administration it can transiently worsen certain symptoms (→pain from bone metastases), secondary amenorrhea, reduced libido, erectile dysfunction, hypogonadism, hot flashes, osteoporosis
Degarelix
MOA: GnRH antagonist;
IND: Advanced hormone-dependent prostate cc;
SEs: erectile dysfunction, glucose tolerance↓, osteoporosis, QT↑, increased cardiovascular risk
Female sexual hormones
Hypothalamus secretes GnRH→ it stimulates the anterior pituitary (hypophysis) to release LH + FSH → they stimulate the ovary to secrete Estradiol + Progesterone→ they then go back and stimulate/inhibit the hypophysis in a negative feedback loop
The function of the ovary
Gametogenic and endocrine
- Quescient before puberty
- At puberty- begins 30-40 years period of cyclic function (menstrual cycle)
- Menopause::explain the stages during female life
Mechanism of action of estrogens
Binds Intracellular receptor →gene activation
Pharmacological effects of estrogen
- Estrogens promote proliferation (endometrium, breast)
- Cooperation with progestins
- Female sexual maturation and growth, secondary sex characteristics, female libido
- Metabolic and cardiovascular effects:
- Normal structure and function of the skin and blood vessels::vascular system
- Decrease the rate of bone resorption (inhibition of osteoclasts)
- higher levels of CBG, TBG, SHBG, transferrin, fibrinogen
- mild, advantageous changes in lipoproteins, TAGs, and cholesterol levels
- Blood coagulation is enhanced (increased synthesis of coagulation factors)
- Activation of the stress and the sympathetic system
- Na+- retention and edema