Pharmacology

Question 1

How do we treat hyperthyroidism (i.e. Graves disease)? How about in pregnant women? What is the major (but rare) side effect?

Answer 1

• treat hyperthyroidism with Methimazole (Carbimazole) or propylthiouracil (PTU); these are thionamides
• MOA: inhibits thyroxine peroxidase
• (note that PTU also functions to block peripheral conversion of T4 into T3)
• Methimazole is teratogenic, so use PTU in pregnancy
• rare but serious side effect: agranulocytosis (leukopenia)

Question 2

How do we treat hypothyroidism?

Answer 2

• with hormone replacement therapy via Levothyroxine
• Levothyroxine is T4
• can give triiodothyronine (T3) as well, but is usually TOO strong of an effect
• very well tolerated, but can result in hyperthyroidism if dose is too high

Question 3

How do we treat acromegaly? What else is this drug used to treat?

Answer 3

• treat acromegaly (excess GH) with Octreotide
• MOA: Octreotide is a somatostatin analog; somatostatin inhibits GH release (it is also known as SRIF in this context: somatotrophin release inhibiting factor)
• also used to treat carcinoid syndrome, diarrhea via VIPoma, gastronome, glucagonoma, insulinoma, and esophageal varices

Question 4

How do we treat hyperaldosteronism? What side effect of this drug commonly affects men?

Answer 4

• treat hyperaldosteronism with spironolactone (or remove tumor)
• MOA: spironolactone acts as an aldosterone antagonist in the cortical collecting tubule; it is K+ sparing
• side effects: gynecomastia (spironolactone also inhibits androgen receptors and increases the conversion of T into estradiol), hyperkalemia

Question 5

How do we treat SIADH?

Answer 5

• treat SIADH with fluid-restriction and Demeclocycline
• MOA: an ADH antagonist
• (can cause nephrogenic diabetes insipidus)

Question 6

How do we treat a pheochromocytoma?

Answer 6

• surgical resection
• give the patient alpha-blockers and then beta-blockers before the surgery*
• alpha-blockers (Phenoxybenzamine or Prazosin) prevent the vasoconstrictive effect of the catecholamines
• beta-blockers (“-olol”) are to control the HR
• *make sure the patient is successfully alpha-blocked before giving the beta-blockers! (beta-blockers prevent vasodilation, so if the patient isn’t fully alpha-blocked beforehand, the catecholamines can induce unopposed alpha-stimulation and extreme vasoconstriction will occur)

Question 7

How do we treat a prolactinoma?

Answer 7

• Bromocriptine, Cabergoline

- these are dopamine agonists

Question 8

How do we treat diabetes insipidus?

Answer 8

• central DI: hydration and desmopressin (DDAVP)

- nephrogenic DI: hydration and hydrochlorothiazide