pitutary and thyroids Flashcards
what is the growth hormone (somatoropin)
- MOA: Stimulates protein synthesis cell proliferation & bone
growth. Also, increases cartilage synthesis.
This effect is either:
a) Directly through GH.
b) Or, indirectly: through somatomedins & insulin-like growth
factors I & II (IGF-I & IGF-II). - Therapeutic uses of somatropin (synthetic human GH):
• Dwarfism due to GH deficiency in children.
• Somatropin is also used to treat children with chronic renal
insufficiency leading to growth deficiency, prader-willi syndrome
and patients with AIDS-related wasting syndrome.
what is somatostatin, octreotide and pegvisomant
3) Growth hormone-inhibiting hormone :
• Suppresses release of GH.
• Octreotide is an analogue with a longer duration of action.
• Used in treatment of gigantism & acromegaly caused by GH-
secreting tumors.
• Pegvisomant is an antagonist of GH receptor normalization of
IGF-I levels used for refractory acromegaly.
what are Gonadotropin-releasing hormone/luteinizing
hormone-releasing hormone:
• Also called: GnRH, gonadorelin.
• Pulsatile secretion is essential for release of
gonadotropins.
• Continuous administration inhibits release of
gonadotropins.
• Pulsatile GnRH is used to stimulate gonadal hormone
production in hypogonadism.
• Leuprolide, goserelin, nafarelin, & histrelin are GnRH
receptor agonists used for treatment of breast cancer,
prostatic cancer, endometriosis, & precocious puberty.
• Leuprolide inhibits gonadotropin release after 1 week of
sustained activity.
• Ganirelix, cetrorelix and degarelix are GnRH receptor
antagonist that inhibits gonadotropin release immediately
what are gonadotropins
• Regulate production of human gonadal steroids.
• Mainly for infertility of men & women.
• Agents:
1. Menotropins (human menopausal gonadotropins, hMG):
– Obtained from urine of menopausal women.
– Contain FSH & LH.
2. Urofollitropin:
– Obtained from urine of menopausal women.
– Contain FSH & devoid from LH.
3. Human chorionic gonadotropin (hCG):
– An LH agonist.
– Also from urine.
4. Follitropin beta:
– FSH produced by recombinant DNA technology.
In females:
– inject hMG or Follitropin beta over 5-12 days
ovarian follicular growth & maturation
– Then: injection of hCG ovulation.
• In males:
– hCG external sexual maturation
– Then: hMG spermatogenesis.
what is the prolactin inhibiting hormones
Prolactin Stimulates lactation & ↓ reproductive activity.
• Hyperprolactinemia causes galactorrhea & hypogonadism.
It is treated with dopamine agonists: bromocriptine, cabergoline and
quinagolide.
A/E: psychiatric problems, pathological gampling, hypersexuality,
increased Raynaud’s phenomenon.
These drugs are also used to stop milk production if the lactating
mother wants to stop breast-feeding
what is oxytocin
IV infusion to induce labor
• IN (intra-nasal) to induce milk let-down
• Prevention & treatment of postpartum hemorrhage.
what is atosiban
Atosiban is an antagonist of the oxytocin receptor that is
used in some countries as a tocolytic (anti-contraction
medications or labor repressants), a drug used to
prevent preterm labour.
what is vasopressin (ADH)
Binds to V2
receptors in collecting ducts antidiuretic effect
Used to treat pituitary diabetes insipidus (not nephrogenic)
• Binds to V1
receptors in blood vessels vasoconstriction.
for bleeding from esophageal varices.
- A/E: water intoxication, hyponatremia, ↑ BP, bronchoconstriction
Conivaptan and tolvaptan are antagonists of vasopressin
receptors: ↓ the fluid retention that results from the excessive
production of vasopressin associated with hyponatremia or acute
heart failure, for treatment of SIADH
what is desmopressin
• More selective for V2
receptors, but still the same
precautions as vasopressin.
• Longer-acting than vasopressin.
• Administered IN.
• For DI (diabetes insipidus) & nocturnal enuresi
what is levothyroxine
• Treatment of hypothyroidism:
• Levothyroxine (T4) sodium.
• Pharmacokinetics:
• Oral.
• Affected by food & antacids.
• Narrow therapeutic window.
• Metabolized in liver inducers decrease its levels
what is liothyronine
• Liothyronine sodium:
• Given as an IV injection in severe hypothyroid states
how do we treat hyperthyroidism (thyrotoxicosis)
1) Removal of part or all of the thyroid:
a) Surgically.
b) Destruction of the gland by beta particles emitted by radioactive
iodine (131I), which is selectively taken up by the thyroid
follicular cells no damage to other tissues.
- Should not be used during pregnancy (category X) or lactation.
- Most patients become hypothyroid as a result & require
treatment with levothyroxine.
- Can also be used for thyroid cancer
2) Inhibition of thyroid hormone synthesis:
• The thioamides: propylthiouracil (PTU), methimazole, &
carbimazole inhibit peroxidase.
• PTU can also block the conversion of T4 to T3.
• These drugs have no effect on the thyroglobulin already stored in
the gland delayed effect.
• Adverse effects: agranulocytosis, edema, rash, liver failure
Use of thioamides in pregnancy (Second & third trimesters):
neonatal goiter, hypothyroidism, & aplasia cutis of the neonate.
3) Blockade of hormone release:
- Lugol’s solution (iodine & potassium iodide) inhibits the
iodination of tyrosines, & inhibits the release of thyroid
hormones from thyroglobulin.
- Also decreases the vascularity of the thyroid gland
hormones of the hypothalamus are?
neuropeptides, any hormone with the word releasing/inhibiting= from the hypothalamus
hormones of the anterior pituitary are?
growth hormone ——-agonist (somatropin and mecasermin)—— antagonist (octerotide and pegvisomant)
Gonadotropins——— LH and FSH
Prolactin
hormones of the posterior pituitary gland
oxytocin and vasopressin
the endocrine control
CNS—–hypothalamus——Pituitary—–endocrine glands
what is the synthesis of thyroid hormones
uptake of iodide—-systhesis of (from amino acids) thyroglobulin—-iodination——condensation—–release
