In treating hypertension, which of the following drugs is NOT useful?

Metformin is primarily used as an antidiabetic medication to manage blood sugar levels in individuals with type 2 diabetes. While it has numerous benefits for diabetic patients, it does not have a significant effect on blood pressure management and is therefore not considered a useful treatment for hypertension.

On the other hand, thiazide diuretics, calcium channel blockers, and angiotensin-converting enzyme (ACE) inhibitors are all classes of medications that are specifically designed to help lower blood pressure. Thiazide diuretics help reduce blood volume and decrease vascular resistance. Calcium channel blockers work by relaxing blood vessels, while ACE inhibitors prevent the formation of angiotensin II, which constricts blood vessels, thereby lowering blood pressure. Each of these drug classes has a well-established role in the management of hypertension.