Pharm-thyroid Flashcards
Adverse effects of radioactive iodine? (3)
-Hypothyroidism
-Worsening of Graves orbitopathy
-Radiation thyroiditis
2 anti-thyroid agents?
methimazole + propylthiouracil
Mechanism of anti-thyroid agents?
Methimazole:
- decreases TH production by interfering with iodination of tyrosine + coupling
Propylthiouracil:
- the same but also affects the conversation of T4 to T3 in periphery
Indication of anti-thyroid agents?
Methimazole:
- hyperthyroid (most cases, children, breastfeeding)
Propylthiouracil:
- hyperthyroidism (1st trimester preg)
- thyroid storm
Adverse effects of antithyroid agents?
Skin rash, allergic reaction and agranulocytosis
Hepatoxicity (rare in methimazole but can be fatal in propylthiouracil)
Why is methimazole CI in 1st trimester pregnancy?
Can cause aplasia cutis
Which drug: Bradycardia, dizziness, fatigue, headache, hypotension
Avoid: asthma, bradycardia conditions
propranolol
Shared Adverse effects of levothyroxine and dessciated thyroid?
-Hyperthyroidism symptoms
-Angina
-glycemic control may decline
Which drug?
Risk of CV + neurological adverse effects in large doses (T3)
- palpitation, tachycardia, arrhythmias, angina
-nervousness, tremors, headache, insomnia
-sweating, heat intolerance, fever, weight loss
desiccate thyroid
Levothyroxine average adult replacement?
1.6 mcg/ kg/ day
Levothyroxine dose for patients with mild or subclinical disease?
25-50 mcg
How long to wait before adjusting?
6 weeks
Adjust in what increments?
12.5-25 mcg
Interactions w/ levothyroxine?
- Absorption may be reduced by antacids + mineral supplementation
- Proton pump inhibitors + estrogens may interfere absorption
- Variable effects w/ anticoagulant drugs
- Separate administration by 6 hrs
- Levothyroxine typically taken 1st thing in the morning before any other meds
Levothyroxine to desiccated thyroid conversion?
1:0.65
