Hypothalamic and Pituitary Hormones PHARM Flashcards
- What is the communication between the hypothalamus and the anterior pituitary?
- What happens normally in the posterior pituitary?
- What do most Pituitary Hormones act on?
- What is the exception?
- vascular link: hypothalamic-pituitary-portal system
- hormones of the posterior lobe of pituitary are synthesized in the hypothalamus, transported to the posterior pituitary, and released into circulation in response to specific physiologic signals
- most act on an endocrine gland before affecting target tissue
- Prolactin
Anterior Pit Secretion
- Hypothalamus creates what?
- What do these do?
- Long Loop Inhibition
- Short Loop Inhibition
- Ultra-short Loop Inhibition
- specific releasing or inhibiting factors/hormones that are released into portal system
- signal release of other hormones from AP that then act on a peripheral endocrine gland or the liver
- end product/ far downstream product acts as inhibitor on pituitary and hypothalamus
- Pituitary hormone inhibits hypothalamus
- Hypothalamus product inhibits its own release
Hypothalamic-Pituitary-Growth Hormone (GH) Axis
- Hypothalamic Homones (2) and action
- Ant Pit Hormone (1)
- Major Target Tissue
- Effects?
- GHRH- releases GH from AP; Somatostatin (SS)- inhibits GH release
- Growth Hormone
- Liver;
- releases IGF-1
Physiological Actions of GH
- In childhood (4)
- In Adulthood (5)
- How is it released?
- How is its secretion affected by age?
- How does it transmit its effects to cells?
- What mediates its effects?
- promotes linear growth: growth of long bones, cartilage, muscle, organ systems
- increases protein synthesis and bone density; promotes lipolysis and inhibits lipogenesis; promotes gluconeogenesis and glucose release; opposes insulin-induced glucose uptake in adipose tissue, reduces insulin sensitivity
- pulsatile manner, mostly during sleep; interplay of GHRH and SS
- decreases
- binds to its receptor and activates cascade mediated by JAK tyrosine kinases and STATs;
- IGF-1
GH Deficiency
- In children
- In Adults
- short stature and adiposity, hypoglycemia (most commonly deficiency of GHRH)
- changes in body composition, increased generalized adiposity; decreased skeletal muscle mass and strength, decreased bone density; CV changes, cardiac muscle atrophy, atherogenic blood lipid profile; fatigue, weakness, depression, overall malaise
Drugs Used in GH Deficiency
- Synthetic GHRH
- Recombinant Growth Hormone (2)
- Recombinant IGF-1
- Sermorelin- used in diagnosis
- Somatropin, Somatrem
- Mecasermin (used where the deficiency is due to mutation of GH receptor)
Somatropin and Somatrem
- Difference between the two
- Mechanism
- Indications for children (3)
- Indications for adults (3)
- 1 amino acid; somatropin is identical to hGH
- replaces GH
- documated growth failure in peds pts associated with: GH deficiency, chronic renal failure, Prader-Willi, Turner syndrome
- Small for gestational age condition w/ failure to catch up by age 2
- Idiopathic short stature, non GH-deficient (>2.25 SD below mean)
- GH deficiency in Adults
- Wasting pts w/ AIDS
- Short bowel syndrome in pts who are also receiving specialized nutritional support
Somatropin and Somatrem
- Controversies
- What do they do in children?
- What do they do in adults?
- Side Effects (5)
- Anti-aging remedies; use by athletes
- increases linear growth and weight gain to low normal range; increases muscle mass, organ size, RBCs
- increases bone mineral density, normalizes body composition (decreased central adiposity); increases muscle mass and strength, improves lipid profile and cardiac function, improves psychological symptoms and sense of well being
- Leukemia, rapid growth of melanocytic lesions; hypothyroidism, insulin resistance, arthralgia, increase in CYP450 activity
Somatropin and Somatrem
- Contraindications (4)
- Considerations
- Drug Interaction (1)
- Pediatric pts w/ closed epiphyses
Active underlying intracranial lesion
Active malignancy
Proliferative diabetic retinopathy - Cautin in diabetics and in children whose GH deficiency results from an intracranial lesion
- Glucocorticoids inhibit growth promoting effect of somatropin
GH Excess
- Usually due to what?
- What does it cause in children?
- What does it cause in adults?
- benign anterior pituitary tumor
- gigantism (occurs before closure of epiphyses)
- acromegaly (occurs after closure of epiphyses): thickening of bones, esp face, hands; large facial structure; increased soft tissue growth; enlarged, arthritic joints; headache, sleep apnea, excessive sweating; increased risk of CV disease, GI cancers,
Medical Treatment for GH Excess
- Somatostatin Analogues
- GH receptor antagonist
- Dopamine receptor agonist
- Octreotide, Lanreotide (used in Europe)
- Pegvisomant
- Bromocriptine
Octreotide
- Describe the drug
- Mechanism
- Indications (4)
- somatostatin analogue, long lasting peptide that is far more potent than SS
- inhibits GH secretion
- used to control pituitary adenoma growht in acromegalic pts
- Carcinoid crisis (flushing, diarrhea, and all symptoms of carcinoid syndrome)
- Secretory diarrhea from vasoactive intestinal peptide (VIP) secreting tumors
- Control acute GI bleeding
Octreotide
- Side Effects (4)
- Contraindications
- What drug levels does it decrease?
- What drug levels does it increase?
- N/V, abdominal cramps, GI discomfort
Cardiac Effects (sinus bradycardia and conduction disturbances)
Hypoglycemia
Gallstones - Hypersensitivity
- Decreases cyclosporin levels
- concomitant administration w/ bromocriptine increases availability of bromocriptine
Pegvisomant
- Describe the drug
- Mechanism
- Indication (1)
- recombinant protein, polyethylene glycol residues prolong half life; GH w/ several amino acid substitutions
- competitive antagonist of GH activity; decreases serum IGF-1 levels
- treatment of acromegaly that is refractory to other modes of surgical, radiologic, or pharmacologic intervention
Pegvisomant
- Side Effects (2)
- Contraindication
- What tests should be performed regularly? (2)
- increased pituitary adenoma size, elevated serum aminotransferase levels
- hypersensitivity rxn
- yearly MRI to exclude enlarging adenoma; liver function tests should be performed periodically
Hypothalamic Pituitary Reproductive Axis
- Role of Continuous GnRH
- Role of Pulsatile GnRH
- Role of Estrogen/Testosterone on Axis
- inhibits LH/FSH release
- activates LH/FSH release
- inhibits LH/FSH release
Hypothalamic Pituitary Reproductive Axis: In Women
- FSH function
- What happens in follicular stage of menstrual cycle?
- What happens in luteal stage of menstraul cycle?
- ovarian follicle development
- LH stimulates androgen production in ovary (theca cells); FSH stimulates conversion of androgens to estrogens (Granulosa cells)
- estrogen and progesterone production is mainly controlled by LH; in pregnancy, these are controlled by hCG made by placenta
Hypothalamic Pituitary Reproductive Axis: In Men
- FSH function
- LH function
- What does FSH do in Sertoli cells?
- regulates spermatogenesis
- stimulates production of testosterone by the testicular Leydig cells
- produces androgen binding protein, which helps maintain high levels of testosterone
Hypothalamic Pituitary Reproductive Axis: Pharm
- In order for pharm therapy to work in infertility, what must be normal?
- What drugs are used to stimulate Axis?
- What drugs are used to inhibit Axis?
- ability of gonads to competently respond to neuroendocrin factors
- Gonadotropins (human menopausal gonadotropins or menotropins, hCG, urofollitropin, follitropin); Gonadotropin Releasing Hormone (GnRH) or its analogue Gonadorelin
- Synthetic analogues of GnRH w/ longer half lives (Goserelin, Histrelin, Leuprolide, Nafarelin, Triptorelin); GnRH receptor antagonists (Ganirelix, Cetrorelix, Abarelix)
Gonadotropins: Describe
- Menotropins
- hCG
- Urofollitropin
- Follitropin
- Mechanism
- Indications (3)
- contain LH and FSH, obtained from urine of menopausal women
- placental hormone and LH agonist
- purified FSH from urine of menopausal women
- recombinant form of human FSH
- Replaces FSH and LH
- Ovulation induction in women w/ anovulation due to hypogonadotropic hypogonadism. polycystic ovary syndrome, obesity
- Controlled ovarian hyperstimulation in assisted reproductive technology procedures (eg IVF)
- Infertility in male hypogonadotropic hypogonadism
Gonadotropins
1. Side Effects (5)
- Ovarian hyperstimulation syndrome (associated w/ ovarian enlargement, ascites, hydrothorax, hypovoluemia, may result in shock);
- increase in multiple pregnancies
- increased risk of gynecomastia in men
- Ovarian cancer
- Ovarian cysts and hypertrophy (hypertrophy subsides after time)
Gonadotropins
1. Contraindications (5)
- Any endocrine disorder other than anovulation
- Primary gonadal failure
- Pituitary tumor or sex-hormone dependent tumors
- Ovarian cyst or enlargement
- Pregnancy
Pulsatile GnRH Agonist
- Describe GnRH
- Describe Gonadorelin
- Mechanism
- Indications (3)
- obtained from hypothalamus
- synthetic human GnRH (short half life)
- pulsatile GnRH secretion or Gonadorelin stimulates LH and FSH release (mimicks physiology)
- Diagnosis of hypogonadism; stimulate ovulation (less cost effective); Infertility in men w/ hypothalamic hypogonadotropic hypogonadism (less cost effective, occasional use)
Pulsatile GnRH Agonist
1. Side Effects (3)
- Anaphylaxis w/ mutliple administrations
- Light headedness, flushing
- Generalized hypersensitivity dermatitis
Sustained GnRH Agonists
- What drugs are synthetic analogs of GnRH?
- What are some advantages to using drugs over native GnRH or gonadorelin?
- Goserelin, Histrelin, Leuprolide, Nafarelin, Triptorelin
2. more potent, longer-lasting
Sustained GnRH Agonists
- Mecahnism
- Describe the response to these drugs
- Sustained nonpulsatile administration inhibits release of FSH and LH in men and women –> inhibition of gonadal axis;
This desensitizes GnRH receptors. - produces biphasic response:
transient flare for 7-10 days (increase in gonadal hormone levels)- agonist effect
Long-lasting suppression of gonadotropins and gonadal hormones - inhibitory action
Sustained GnRH Agonists
How is the flare prevented/minimized?
With co-administration of an androgen antagonist
Sustained GnRH Agonists: Indications (5 + which drugs are indicated for which)
- Keep LH surge low in controlled ovarian hyperstimulation that provides multiple mature oocytes for assisted reproductive technologies (Leuprolide, nafarelin, goserelin)
- Endometriosis and Uterine fibroids (leuprolide, nafarelin, goserelin)
- Adjunctive in prostate cancer (leuprolide, goserelin, histrelin, triptorelin)
- Central precocious puberty (leuprolide, nafareling)
- Others (advanced breast and ovarian cancer, amenorrhea and infertility in women w/ polycystic ovary disease)
Sustained GnRH Agonists
- Side Effects (4)
- Contraindications (3)
- Symptoms of menopause (hot flashes, sweats, headache); Osteoporosis; Urogenital atrophy; Temporary worsening of precocious puberty during the initial weeks of treatment
- Hypersensitvity; pregnancy; breast feeding
GnRH Receptor Antagonists
- Name the drugs (3)
- Mechanism
- What do these lack that GnRH receptor agonists have?
- Ganirelix, Cetrorelix, Abarelix; G and C produce immediate antagonistic effects
- competitive antagonists of GnRH receptors, inhibits secretion of FSH and LH in dose dependent manner
- flare effect
GnRH Receptor Antagonists: Indications
- Ganirelix and Cetrorelix
- Abarelix
- keeps LH surge low in controlled ovarian hyperstimulation for assisted reproductive technologies resulting in improved rates of implantation and pregnancy
- metastatic prostate cancer in pts with extensive metastases or tumor encroaching on the spinal cord
GnRH Receptor Antagonists
- Side Effects in general
- Side Effect of Abarelix
- Side Effects of Ganirelix (3)
- Side Effect of Cetrorelix
- Contraindications (4)
- ovarian hyperstimulation syndrome;
- QT interval prolongation
- Ectopic pregnancy, thrombotic disorder, spontaneous abortion
- Anaphylaxis
- Pregnancy, lactation, ovarian cysts or other enlargement;
Primary ovarian failure;
Thryoid or adrenal dysfunction;
Vaginal bleeding of unknown etiology
Hypothalamic-Pituitary-Prolactin Axis
- What cell type in AP produces and secretes prolactin?
- What inhibits Prolactin release?
- What increases Prolactin release?
- Describe negative feedback
- What is the role of estrogen?
- What is a powerful stimulus for release?
- Lactotrophs
- dopamine
- thyrotropin-releasing hormone
- There is none, because prolactin does not stimulate hormone secretion
- stimulates prolactin release, but antagonizes prolactin action; prevents lactation until after parturition
- suckling
Physiologic Actions of Prolactin (3)
- regulates mammary gland development,
- milk protein biosynthesis and secretion
- inhibits GnRH release, suppresses ovulation during lactation
Disorders of Hyperprolactinemia
- Destruction of what can cause it?
- How is it commonly caused?
- Symptoms of Hyperprolactinemia (3)
- hypothalamic destruction
- prolactin secreting adenomas
- amenorrhea, galactorrhea, and infertility in women
- Loss of libido and infertility in men
- can compress optic nerves and cause visual changes
Pharmacology of hyperprolactinemia
- Drugs Used
- What is used to treat prolactin deficiency?
- Dopamine Receptor Agonists: Bromocriptine, Cabergoline, Pergolide (all are D2 receptor agonists)
- nothing, yet
Bromocriptine, Cabergoline, Pergolide
- Mechanism
- Indications (3 + drugs)
- Inhibit pituitary prolactin release; GH release is reduced in pts w/ acromegaly, less effective
- Amenorrhea, galactorrhea, infertility from hyperprolactinemia, premenstrual syndrome (Bromocriptine, Cabergoline)
- Acromegaly (Bromocriptine- requires high doses)
- Parkinson’s Disease (Bromocriptime, Pergolide, Cabergoline)
Bromocriptine, Cabergoline, Pergolide
- Side Effects of all of them
- Side Effects of Bromocriptine
- Side Effects of Pergolide
- Side Effects of Cabergoline
- Orthostatic hypotension
- Cerebral vascualr accidnet, seizure, acute MI
- Arrhythmia, MI, heart failure
- Pulmonary fibrosis and pleural effusion
Bromocriptine, Cabergoline, Pergolide
- Contraindications (3)
- Which causes less nausea?
- What route of administration can reduce nausea but cause local irritation?
- Intolerance to what may occur?
- What potentiates hypotension?
- What drugs have additive effects?
- Hypersensitivity to ergot derivatives
- Uncontrolled HTN
- Toxemia of Pregnancy/Ecclampsia (Bromo)
- Cabergoline
- Intravaginal
- alcohol
- antihypertensives
- CNS depressants