Endocrine Drugs Flashcards
Two Thioamide drugs that are used for treating Hyperthyroidism?
Propylthiouracil
Methimazole
MOA of PTU & Methimazole?
1) Prevent Iodine incorporation with Tyrosine residues on Thyroglobulin protein.
2) Inhibits Thyroid Peroxidase enzyme (so Iodine cannot be converted into free atomic form).
Which one (PTU or Methimazole) has peripheral tissue effects? What enzyme does it inhibit?
PTU… Inhibits T4 to T3 conversion via enzymatic inhibition of 5’-deiodinase.
Common drug s/e’s of PTU & Methimazole?
-GI Upset
-Rash
-Arthralgia
Severe drug s/e’s of PTU & Methimazole?
-Agranulocytosis
-Neutropenia
-Polyarthritis
-Hepatotoxic
-Vasculitis
What other drug can be used to reduce cardiac over-stimulation due to Hyperthyroidic conditions?
Propranolol
-Or any Beta Blocker that doesn’t have Intrinsic Sympathomimetic Activity.
T or F: Radioactive Iodine (as a Curative Therapy for Hyperthyroidism) can temporarily worsen Hyperthyroidic symptoms.
True!
What do we need to do for those undergoing Curative Therapies for Hyperthyroidism?
Potential supplementation with Mg2+ & Ca2+ (as PTH levels are typically lower in these pt.’s).
Standard 1st line therapy for Hypothyroidism?
Levothyroxine (T4 analogue)
What is Liothyronine good for?
Cases in which T4 to T3 conversion is impaired (rare).
What important drug interactions does Levothyroxine have?
-Antacids
-H2 Blockers
-PPI’s
-Ca2+ & Iron Supplements
Avg. weight based dosing regimen for Levothyroxine?
1.6mcg / kg / day
Levothyroxine gets titrated up by what amounts every 4-6wks?
12.5-25mcg
If I have elevated TSH levels, should I increase or decrease my Levothyroxine dose?
Increase…
-High TSH means Low T3 / T4 levels (as we have increasing suppression).
1 therapy choice for Cushing’s Syndrome (ie. Elevated Cortisol)?
Surgery
