Examples: Methimazole (MMI) and Propylthiouracil (PTU)
Choice: Methimazole is preferred over propylthiouracil due to a slightly better safety profile and potency
Pregnancy: In first trimester, propylthiouracil is preferred, whereas second and third trimester, methimazole is preferred
Dosing: divided doses 2 to 3 doses, with food
Adverse Effects:
-rash
-joint pain, upset stomach
-increased liver function tests and hepatotoxicity (higher risk with PTU)
-agranulocytosis (rare): monitor for signs of infection (sore throat, fever)
-nephrotoxicity (rare)
Interactions:
-warfarin: may lead to a decrease in INR
-theophylline: may lead to increased theophylline levels
-digoxin: may increase digoxin levels
-avoid other medications that cause agranulocytosis: clozapine