hypothalamic-pituitary hormones (Exam 1) Flashcards
What is another name for the Growth Hormone?
Somatropin
A child needs replacement therapy of growth hormone. Which is more effective for dosing?
A. Daily at bedtime via SC or 3 times a week IM?
daily at bedtime via SC- this mimics natural release pattern
What can you use to treat children who have a growth hormone insensitivity? (laron dwarf)
can treat recombinant IGF-1
What is the drug name for recombinant IGF-1?
Mecasermin-Increlex
What should pts due before injecting recombinant IGF-1?
Eat some carbs before injection because there is a concern for hypoglycemia
What is the most common causes of growth hormone deficiency?
usually due to pituitary tumor or consequences of its treatment- (surgery/radiation )
What increases the release of growth hormone?
the release is increased by GHRH
What decreases the release of growth hormone?
somatostatin also paradoxically decreased by dopamine agonists in acromegaly
limited studies of Illicit use of growth hormone in the elderly for anti-aging suggest what?
That it is associated with small changes in body composition and INCREASED rates of adverse effects (edema, joint pain, muscle pain, carpal tunnel
True or false can your recommend growth hormone to the elderly for anti aging?
False it can not be recommended
What side effects can occur with the use of somatropin?
- insulin resistance and glucose intolerance may occur
- Slight increased risk for idiopathic intracranial hypertension
- Rarely pancreatitis, gynecomastia, nevus growth
What is somatostatin?
This is a growth hormone- inhibiting hormone can also be called Somatotropin release-inhibiting factor
Where is somatostatin present in the body?
it is in the…
- hypothalamus
- nervous system
- gut
- endocrine and exocrine glands
True or false: Somatostatin inhibits GH release via GPCR coupled to Gi decreasing cAMP levels and activating K+ channels
True
True or false Beetches: somatostatin INCREASES secretion of gastric enzymes and acid- INCREASED GI motility- STIMULATES the release of serotonin
False. The bolded words should be
- decrease
- decreased
- suppresses
True or false: Somatostatin reduces insulin and glucagon release
True
Does somatostatin interfere with TRH ability to release TSH
yes it does
What is the half life of somatostatin following exogenous administration?
it is only 3-4 min which limits its therapeutic effects
What organ system has a major role in the clearance of somatostatin?
The kid knees
What are the names of two other meds that are similar to somatostatin?
Octreotide and Lanreotide
What is the half life of Octreotide in the plasma? how long does it last? How often is it given and by what method?
- plasma half life 90min
- duration 12 hours
- Given SC every 6-12 hours
How else can Octreotide be given and how often?
can be IM and every 4 weeks
How is Lanreotide administered and how often?
SC and every 4 weeks
What is Octreotide and Lanreotide used for?
- Pituitary or excess of growth hormone
2. control of bleeding from esophageal varices and GI hemorrhage
What are two conditions associated with pituitary excess where Lanreotide and Octreotide can be used?
- Acromegaly and gigantism
What treatment is preferred for when the pituitary releases excess growth hormone?
Surgical resection- unless adenoma does not appear fully resectable
After a response is seen with the use of SC Octreotide, what med is utilized next
Long acting somatostatin analog
Are dopamine agonists as effective as SST (somatostatin) analogs?
no they are not; however Cabergoline is a preferred agent for adjunctive management of acromegaly with advantage of oral administration
What is Pegvisomant (somavert)?
- this is a GH receptor antagonist
- It binds to receptors blocking GH access, but does not activate signaling transduction
- administered single dose SC
true or false: SST analogs can be used for WDHA (watery diarrhea, hypokalemia, achlorhydria)
True
What is a side effect of SST drugs?
- transient hyperglycemia
- cardiac effects (brady and conduction disturbances)
what is prolactin release under control of?
under inhibitory control by hypothalamic dopamine at D2 receptors
what is the main stimulus for the release of prolactin?
suckling causes 10-100 fold increase
If there are sufficient levels of, insulin, estrogen, progestin, and corticosteroids what will prolactin stimulate?
milk production
Prolactin stimulates milk production, what else does it stimulate?
Proliferation and differentiation of mammary tissue during pregnancy?
So what does prolactin inhibit?
inhibits gonadotropin (FSH/LH) release and or ovarian response to these hormones
What two drugs are used for prolactin issues?
Cabergoline and bromocriptine
Is there any treatment available for prolactin deficiency?
no there isn’t
why are prolactinomas that cause hyperprolactinemia amenable to pharmacotherapy?
this is because of the availability of dopamine agonists that both decrease secretion and reduces tumor size.
What are some frequent side effects of bromocriptine?
nausea, vomiting, headache, postural hypotension
Does bromocriptine activate D1 receptors?
yes
What is the preferred agent for hyperprolactinemia?
Cabergoline
which is more selective for D2 receptors? and more effective in reducing prolactin secretion?
cabergoline
which is better tolerated? cabergoline or bromocriptine?
cabergoline
What is another name for vasopressin?
it is the antidiuretic hormone, ADH
what is the half life of vasopressin?
about 20 minutes
Which one is more stable desmopressinor vasopressin?
desmopressin, it has a half life of 1.5-2.5 hours
What part of the kidney does desmo and vasopressin act on?
the collecting tubules
What are the stimuli in the body that cause the release of vasopressin?
- main stimuli is rising blood osmolarity
2. decrease circulating blood volume
True or false: alcohol can inhibit the release of ADH
true
What receptors mediate the renal actions of ADH?
V2 receptors
What are the non-renal actions of ADH?
release of coagulation factor VIII and von willebrands factor
Other than the V2 receptors what other receptors does ADH-vasopressin act on?
V1 receptors
What is the effect of ADH on V1 receptors?
- mediates vasoconstriction of vascular smooth muscle
- BUT pressor responses only at much higher concentrations than for maximal antidiuresis
Central diabetes insipidus is a posterior pituitary disease resulting in hypofunction. what two medications can be used to treat it?
- Desmopressin
2. Chlorpropamide
What is central diabetes insipidus?
this is when you have inadequate ADH secretion from the posterior pituitary
Which of the two is the treatment of choice for central diabetes insipidus? why?
A. Desmopressin
B. Chlorpropamide
A. Desmopressin because it is highly selective for V2 receptor with little vasopressor or uterotonic actions
Can desmopressin be given nasally?
Yes and an adverse reaction can be nasal irritation.
When taken orally what can be some adverse reactions?
- Mild elevation of liver enzymes
- asthenia
- water intoxication,
- abdominal cramps
What 2 drugs can induce nephrogenic diabetes insipidus?
- Lithium. This drug reduces V2-receptor mediated stimulation of adenyl cyclase
- Demeclocycline- possibly acts via block of ADH binding to receptor
What is one treatment for nephrogenic diabetes insipidus that doesnt seem to make sense?
The use of thiazide diuretics
How does the use of thiazide diuretics work for nephrogenic diabetes insipidus?
Paradoxically reduce the polyuria of patients.
-somehow antidiuretic effect parallels ability to cause natriuresis
Other than the use of thiazide diuretics for nephrogenic diabetes insipidus what other drug can you use?
NSAIDS
how do NSAIDS work for nephrogenic diabetes insipidus?
Prostaglandins attenuate ADH-induced antidiuresis so INHIBITION of PG synthesis by indomethacin may relate to the antidiuretic response.
-INDOMETHACIN HAS GREATEST EFFICACY AMONG NSAIDS
What combined therapy can be used for treatment of nephrogenic diabetes insipidus?
Thiazide and indomethacin
We have talked about hypofunction of posterior pituitary. What is a condition of hyperfunction of posterior pituitary?
SIADH
What disorders can cause SIADH?
- Malignancies
- Pulmonary disease
- CNS trauma, infections, tumor
What drug classes most commonly implicated can lead to life threatening hyponatremia and then seizures?
- Psychotropic agents: SSRIs, haloperidol, tricyclic antidepressant
- Sulfonylureas (chlorpropamide)
- Vinca alkaloids chemotherapy
- Methylenedioxy methamphetamine (MDMA)
what is the initial conservative approach for treatment of hyponatremia?
initially just restriction of free water intake
What drug inhibits ADH effect on distal tubule and has been the preferred drug in patients with inadequate response to conservative therapy for Hyponatremia?
Demeclocyline
What two drugs are V2 receptor antagonists and have been used for hyponatremia?
- Tolvaptan
2. Conivaptan
If severe symptomatic hyponatremia is present, what can be given along with conivaptan?
hypertonic saline 3% which permits a more rapid correction
If there is a to rapid correction of hyponatremia what can occur?
cerebellar pontine myelinolysis
Vasopressin is a V1 receptor mediated drug. Can it be used for bleeding in esophageal varices? is there another option that is better tolerated and preferred?
- Vasopressin can be used
2. The better option is octreotide
True or false: Vasopressin can be used for severe septic shock and formerly used for shock-refactory ventricular tachycardia?
True
Which medication is V2 receptor mediated and can be used for nocturnal enuresis?
Desmopressin
What two blood conditions can desmopressin be used for?
- Von willebrands disease
2. Moderate hemophilia A (elevates factor VIII)
