Used primarily as an anti-anginal agent to prevent and treat chest pain (angina pectoris) by dilating blood vessels and improving blood flow to the heart. It works by releasing nitric oxide, which relaxes smooth muscles in vessel walls, reducing cardiac workload and oxygen demand. Often administered sublingually or in sustained-release oral forms for rapid or prolonged effect. Also used in patients with coronary artery disease to manage acute episodes or as prophylaxis before exertion. May be part of combination therapy with other cardiovascular drugs.