Block 5: Gonads Breese Flashcards
What is the function of Gonadotropin Releasing Hormone (GnRH)?
Stimulates anterior pituitary gland to release FSH and LH
What is the function of FSH and LH?
- Increases the secretion of estrogen and progesterone in females
- Increases the secretion of testosterone in males
What occurs in the phases of ovulation?
Follicular: LH and FSH concentrations increase due to GnRH
Ovulation: Follicle released from ovary -> secretes estrogen
Luteal: Progesterone prepares the endometrium to receive and nourish a fertilized egg
What is the MOA of GnRH antagonists?
- Competitively and reversibly bind to GnRH receptors in the pituitary gland, blocking the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the anterior pituitary
- Abolish gonadal sex hormone production and suppress sex hormone levels
What are the types of GnRH antagonists?
- Cetrotelix (Cetrotide)
- Degarelix (Firmagon)
- Ganirelix
- Elagolix (Orilissa)
Danazol
Brand, MOA, Indication
Danocrine
MOA: Inhibits release of GnRH and consequently, the gonadotrophins (FSH and LH), preventing the mid-cycle surge in the levels of FSH and LH during the menstrual cycle
Indication: Endometriosis
Describe the biosynthesis of estrogens and testosterone?
What is the primary female sex hormone?
Estrogen
What is the function of estrogen?
- To develop secondary female sex characterisitcs
- Thickens endometrium
- Regulate menstrual cycle
How is estrogen regulated?
FSH and the LH
Hypothalamus → GnRH → Pituitary → FSH → Follicle → Estrogens
What are the estrogen receptors?
ERa and ERb
What are the types of estrogen preparations?
Natural: estradiol
Synthetic: mestranol, ethinyl estradiol
What are the clinical uses for estrogen?
- Oral contraception
- Hypogonadism
- Postmenopausal Hormonal Therapy
- Suppress ovulation in patients with intractable dysmenorrhea or hirsutism
- Fertility treatments
What is the pregnancy rate of using contraception perfectly?
0.5–1 per 100 woman years
What are the ADRs of estrogens?
- Tenderness of breasts
- NV
- Anorexia
- Retention of salt and water
- Breakthrough breeding
- Thromboembolism, carcinoma
CI of Estrogens?
- Pregnancy
- Incomplete bone growth
- Genital bleeding
- Strke
- TEDX, HDX
- BRCA gene
DDIs for estrogen?
↓ efficacy of oral anticoagulants and hypoglycemic agents
↑ adverse effects of tricyclic antidepressants
↑ the effects of oxytocin on the uterus.
St. John’s wort may cause loss of contraceptive or hormonal-replacement efficacy of estrogens
What are SERMs?
Tissue specific activity
1. Estrogenic activity for bone growth;
2. Anti-estrogenic for uterine endometrial growth (raloxifene) and in estrogen receptor positive (ER+) breast cancers
Raloxifene
Brand, MOA, INdication, ADR, Interactions
Evista
MOA: High affinity for both ER-a and ER-b
Indication: Osteoporosis
ADR: DVT and PE
Interaction: Decrease warfarin efficacy
What are the types of SERMs?
- Toremifene (Fareston)
- Ospemifene (Osphena)
- Raloxifene (EVISTA)
What are aromatase inhibitors?
- blocks the local production of estrogens in hormonally-responsive tissues
- Do not have the bone protecting activity of tamoxifen, and may require adjuvant therapies to prevent bone loss
What are the types of aromatase inhibitors?
Steroidal: exemestane (AROMASIN)
Non-steroidal: anastrozole (ARIMIDEX), letrozole (FEMARA)
Clomiphene
Brand, MOA
Clomid
MOA: Increases secretion of GnRH and gonadotrophins and induces ovulation
What are the anti-estrogens?
Clomiphene (Clomid)
Fulvestrant (FASLODEX)
Where is progesterone produced?
- Adrenal glands
- Gonads
- Brain
- Placenta
How is progesterone regulated? What is the primary effect?
Stimulated by the production of LH
Hypothalamus → GnRH → Pituitary → LH → Corpus luteum → Progesterone
Primary effect: Prepares uterus for implantation by the proliferation of endometrium and prepares body for pregnancy
What is the action of natural progesterone?
Destroyed by digestive enzymes and acids when used orally
What is component is in all oral contraceptives?
Progesting, synthetic form of progesterone
Why is progestin in all oral contraceptives?
In adequate doses, they inhibit ovulation
Due to progesterone’s low bioavailability, what products were created to increase efficacy?
- Medroxyprogesterone (Provera, Depo-Provera): 17-a-hydroxy-progesterone derivatives have substitutions at C17 that slow hepatic metabolism
- Norethindrone: 19-nor testosterone derivatives display primarily progestational with moderate estrogenic and androgenic activity
- Norgestrel / Levonorgestrel: Replacement of the 13-methyl group of norethindrone with a13-ethyl substituent
- Desogestrel and Norgestimate