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
