Which of the following medications is known to cause elevated prolactin levels?

Verapamil is a calcium channel blocker primarily used to manage hypertension and angina. It has the potential to increase prolactin levels due to its action on dopamine pathways. Dopamine usually inhibits prolactin secretion from the anterior pituitary gland. When dopamine receptors are blocked or inhibited—as can occur with verapamil—the inhibitory control over prolactin release is diminished, leading to elevated levels of this hormone.

In contrast, medications like ibuprofen, acetaminophen, and metformin do not have a straightforward association with increased prolactin levels. Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID) and generally does not influence hormone levels significantly. Acetaminophen, used primarily for pain relief and fever reduction, also lacks evidence linking it to increased prolactin secretion. Metformin, primarily an oral hypoglycemic agent used in the management of type 2 diabetes, does not typically cause elevations in prolactin levels and is rather neutral when it comes to hormonal influence in comparison to verapamil.