What is the action of antithyroid agents?

Antithyroid agents are primarily designed to reduce the production and release of thyroid hormones, which are typically overproduced in conditions like hyperthyroidism. By inhibiting the synthesis of these hormones, antithyroid agents effectively alleviate the symptoms associated with hyperthyroidism, such as anxiety, rapid heartbeat, and weight loss. This symptom relief is essential for restoring balance and improving the patient's quality of life.

The other options present actions that are not aligned with the purpose of antithyroid medications. For instance, increasing thyroid hormone production, enhancing overall thyroid function, or managing thyroid cancer do not accurately reflect the intended use of these medications, which specifically aim to control excessive hormone levels.