Which antiarrhythmic drug is likely to have side effects related to thyroid function?

Amiodarone is known for its significant impact on thyroid function due to its structural similarity to thyroid hormones and its iodine content. This drug can induce both hypothyroidism and hyperthyroidism because it contains approximately 37% iodine by weight. The excessive iodine can lead to changes in thyroid hormone production, resulting in these thyroid dysfunctions.

In hypothyroid patients, the high iodine levels can cause the thyroid to underperform, leading to symptoms such as fatigue, weight gain, and cold intolerance. Conversely, in some individuals, amiodarone can provoke an overproduction of thyroid hormones, leading to hyperthyroid symptoms such as weight loss, heat intolerance, and increased heart rate.

This unique aspect of amiodarone underscores the necessity for monitoring thyroid function in patients undergoing treatment with this medication. Other antiarrhythmic agents listed do not share the same level of interaction with thyroid physiology, which is why amiodarone is specifically recognized for its potential side effects related to thyroid function.