What is the primary action of hydralazine hydrochloride?

Hydralazine hydrochloride is primarily recognized as a vasodilator, which means it works to relax blood vessels. This relaxation results in a decrease in total peripheral resistance, which in turn helps to lower blood pressure. The mechanism of action involves direct relaxation of arterial smooth muscle, leading to vasodilation. As the blood vessels widen, blood flow increases, reducing the workload on the heart.

While various other drug classes have different mechanisms, options like anticoagulants are not relevant to hydralazine as they work to prevent blood clots rather than affect blood vessel dilation. Similarly, hydralazine does not primarily function by increasing heart rate or blocking calcium channels, as these actions are characteristic of other drug classes. By focusing on its role as a vasodilator, we can understand how hydralazine effectively contributes to managing conditions like hypertension and heart failure by alleviating increased vascular resistance.