06c Hormonal Agents Camarero Flashcards
What is the rationale behind Hormonal Agents?
Some of the tumors of endocrine origin (breast, prostate, endometrium) may (or may not) have hormone receptors. This determines whether they may respond to endocrine stimuli/inhibition
What are the sub-classes of hormonal agents used?
Estrogen & Androgen Inhibitors. Gonadotropin-Releasing Hormone Agonists. Aromatase Inhibitors
What are the Estrogen & Androgen Inhibitors used?
Tamoxifen
What are the Gonadotropin-Releasing Hormone Agonists used?
Leuprolide
What are the Aromatase Inhibitors used?
Aminogluthethimide
What are Antiestrogens?
Selective estrogen receptor modulator (SERM), possess both estrogenic and antiestrogenic effects on various tissues. Binds to estrogen receptors (ER) and induces conformational changes in the receptor. Has antiestrogenic effects on breast tissue. The ability to produce both estrogenic and antiestrogenic affects is most likely d/t the interaction with other coactivators or corepressors in the tissue and the binding with different estrogen receptors, ER-a and ER-B. The expression of estrogen dependent genes is blocked or altered. Resulting in decreased estrogen response
What is Tamoxifen?
Antiestrogen. Most of Tamoxifen’s effects occur in the G1 phase of the cell cycle
How is Tamoxifen administered?
Orally and is rapidly absorbed from the GI tract. Drug distributes widely through the body. Extensively metabolized in the liver
What are the therapeutic uses of Tamoxifen?
Can be used as primary therapy for metastatic breast cancer in both men and postmenopausal women. Reduces breast cancer incidence when used prophylactically
What is the toxicity associated with Tamoxifen?
Hot flashes, fluid retention and nausea
What is Megestrol?
Antiestrogen. Synthetic oral progestin (induces endometrial secretory changes, increases basal body temperature, inhibits pituitary function)
What is Megestrol used for?
To stimulate appetite in AIDS patients and as antieoplasic (breast, renal cell and endometrial carcinoma)
What is the MOA of Megestrol?
Suppression of luteinizing hormone release may have negative effect on cancerous tissues (breast and endometrial lining). Enhances estrogen metabolism, which may suppress estrogen-dependent tumors by lowering plasma estrogen concentrations
What is the PK/PD of Megestrol?
Rapidly absorbed across the GI tract. BA > 90%. Strongly bound to plasma proteins. Tendency to concentrate on adipose tissue. Completely metabolized by the liver. Major route of drug/metabolites elimination is urine
What is the toxicity related to Megestrol?
Adrenal insufficiency
What is the MOA of Antiandrogens?
Compete with ligand for AR binding (sequesters AR in cytoplasm). Prevents dimerization and/or DNA binding, prevents formation of active transcription complex
What is Flutamide?
Oral nonsteroidal Antiandrogen used in the treatment of metastatic prostatic carcinoma. Most effective when used in combination with LHRH antagonists (e.g. Leuprolide). Not effective in treating other hormonally dependent diseases (breast cancer or benign prostatic hypertrophy). Antiandrogenic effects mediated by inhibition uptake and/or nuclear binding of testosterone and dihydrotestosterone by prostatic tissue