Anti -thyroid

Hyperthyroidism

1) Thioamides - carbimazole, propylthiouracil, methimazole --> block synthesis of thyroid hormone
How to start??
starts at a high daily dose of 15 - 40mg continued until the patient has normal thyroid function. Then reduced to a maintenance dose of 5 - 15mg.
Treatment is usually given for 12 - 18 months followed by a trial withdraw
SE : rashes & pruritus --> if due to carbimazole cn change to PTU
bone marrow suppression (ask patient to come if has fever,sore throat)- Monitor WBC 3monthly
PTU can also cause fulminant liver failure --> death
PTU & methimazole - use in pregnancy. PTU (1st trimester) da rest is methimazole

2) Beta blocker - adrenoreceptor blocker
treat tremor & tachycardia

3) radioactive iodine (131 - I)
MOA : incorporate into storage follicles & destroy tissue internally

4) Iodide replacement agent (pottasium iodide)
MOA : inhibit thyroglobulin proteolysis --> inh hormone release --> decrease overactivity of thyroid

Hypothyroidism

Levothyroxine (synthetic T4) , Liothyronine (synthetic T3)
MOA : actions as endogenous hormone. enter cells, convert T4 to T3, T3 enter nucleus, bind to specific receptor protein, activate the synthesis