A 57-year- old lady came with chief complaints of fatigue. On fuher questioning, she reveals that she has gained 5 kg weight in one month. She has been taking L-thyroxine for hypothyroidism since 10 years and fairly controlled. Recently she was staed on an anti-arrhythmic drug for treatment of his cardiac condition. The symptoms staed after sta of this drug. Most likely anti-arrhythmic drug she was prescribed is?

The patient is already a case of hypothyroidism stabilized on thyroxine. Amiodarone is an antiarrhythmic drug with side effects on the thyroid gland and thyroid hormones. It inhibits peripheral conversion of T4 to T3. It contains iodine and can inhibit the formation of thyroid hormones. Most likely Amiodarone would have resulted in loss of control over the hypothyroidism. Procainamide, lidocaine and verapamil are also anti-arrhythmics but have no role on thyroid.