Gonadal hormone Pharmacology Flashcards
Name two GnRH analogs.
- Gonadorelin hydrochloride(Factrel®)
- Gonadorelin diacetate tetrahydrate(Cystorelin®)
- Both are injectable
Describe the pharmacokinetics/dynamics of GnRH analogs.
1) Highly bioavailable and more stable than native GnRH peptide:
2) Can be administered as a nasal spray, SC injection, IM injection, or in a SC time-release device.
3) Renal clearance.
What are the indications for GnRH analogs?
- Suppression of estrogen production in hormone-dependent breast cancer
- Suppression of androgen production in hormone-dependent prostate cancer
- Delay the onset of precocious puberty. (Also used to delay puberty in transgendered youth who are too young for hormone-replacement therapy.)
- Hypergonadism: Disrupts the GnRH pulse generator
What contraindications are associated with GnRH analogs?
- Pregnancy
What precautions should be taken in male patients on GnRH analogs?
- Increased risk of diabetes, MI, sudden cardiac death, stroke; monitor blood glucose and for signs/symptoms of CVD during therapy.
- Co-symptomatic with androgen suppression/Low Testosterone.
- Risk of ureteral obstruction or spinal cord compression
What precautions should be taken in female patients on GnRH analogs?
- Not recommended for nursing mothers and abnormal vaginal bleeding
- Risk factors for decreased bone mineral density (e.g. chronic alcohol, tobacco, anticonvulsants, corticosteroids).
- Premenopausal women: use nonhormonal contraception during and for 12 weeks after therapy or until menses resume.
What states do steroid receptor exist in the absence of an agonist?
1) In the cytoplasm of androgen target cells associated with a multi-protein complex known as the heat-shock complex.
2) Bound to target genes and associated with a co-repressor complex with innate histone-deactylase activity.
Describe the state of a steroid receptor in the presence of an antagonist.
In the presence of an antagonist a steroid receptor is bound to target genes and associated with a co-repressor complex with innate histone deactylase activity.
Where is estrogen produced in the female body?
Most estrogen in the female is produced in the ovaries by the theca interna and the granulosa cells of the follicles
What are the clinical uses of estrogen?
- Contraception
- Hormone Replacement Therapy
- Oncology (anti-estrogens»estrogens)
- Male to female transgender promotion
What are the systemic effects of estrogen?
- Ovaries : stimulate follicular growth; small doses cause an increase in weight of ovary; large doses cause atrophy
- Uterus: endometrial growth
- Vagina: cornification of epithelial cells with thickening and stratification of epithelium
- Cervix: increase of cervical mucous with a lowered viscosity (favoring sperm access)
- Development and maintenance of internal (fallopian tubes, uterus, vagina), and external genitalia.
- Mammary gland: Promotes ductal outgrowth and branching during puberty and in each mammary regenerative cycle.
- Skin: increase in vascularization, development of soft, textured and smooth skin
- Bone: increase osteoblastic activity
- Electrolytes: retention of Na+, Cl- and water by the kidney
- Cholesterol: hypocholesterolemic effect
What is the mechanism of estrogen as a contraceptive?
- Ectopic estrogen treatment mimics the negative feedback on the HPG axis resulting in reduced LH and FSH production.
- Many formulations include progesterone which help to offset unwanted side-effects of estrogens.
How is estrogen administered when used as a contraceptive?
Can be delivered orally or via injection, transdermally or placement of a time-release implant.
What types of breast cancer are tamoxifen and Arimidex
used for?
- Useful for hormone dependent breast cancer
What is the mechanism of action of Tamoxifen?
- Selective inhibitor of the hormone-binding domain of the estrogen receptor.
- Selective Estrogen Receptor Modulator (SERM) that has anti-estrogenic activity in certain tissues (e.g. mammary gland) and estrogenic activity in others (e.g. uterus).
- Has been shown to reduce the risk of breast cancer recurrence.