Thyroxine

Question 1

Give an example

Answer 1

Levothyroxine

Question 2

What are the indications for use

Answer 2

• 1o hypothyroidism

- Hypothyroidism 2o to hypopituitarism

Question 3

What is the mechanism of action

Answer 3

• Thyroid hormones regulate metabolism + growth

- Synthetic T4 or T3 used to replace

Question 4

What are the side effects

Answer 4

• excessive dose can mimic hyperthyroidism
• cardiac (palpitations, angina, arrhythmia)
• neuro (tremor, insomnia, restlessness)

Question 5

What are the contra-indications

Answer 5

• CAD
• HYPOPITUITARISM
  (corticosteroid therapy initiated first to avoid Addisonian crisis)

Question 6

What are the interactions

Answer 6

• Antacids
• Ca/IRON
• Salts (reduced absorption)
• Inducers (phenytoin, carbamazepine, insulin, warfarin