Amiodarone

- Amiodarone has high iodine content (40% of its weight)
- can directly cause both sinus bradycardia and AV block due to its calcium channel blocking activity
- prolonged QT interval due to blockage of potassium channels

Side effects of Amiodarone : BITCH

• B - Bradycardia
• I  - Interstitial pulmonary fibrosis
• T - Thyroid disorder (hyper/hypo)
• C - Corneal microdeposits (visual haloes & photophobia)
• H - Hepatitis / Hypersensitive skin (slate grey)

Amiodarone-induced hyperthyrodism

- Type 1 : high iodine content cause release of thyroid hormones (Jod Basedow effect). Positive antithyroid antibodies,normal IL-6

- Type 2 : amiodarone cause destructive thyroiditis, raised IL-6
- colour flow doppler ultrasound can differentiate (increase in type 1 and reduced in type 2)

- treatment: antithyroid in type 1, steroid + antithyroid for type 2
                  consider stop amiodarone if possible

Amiodarone also can cause hypothyroidism by inhibiting the peripheral conversion of T4 to T3 (thus elevated T4, low T3 and raised TSH)