Question

A patient takes a nitroglycerin tablet subligually for chest pain. Nitroglycerin acts directly on smooth muscle, producing relaxation and vessel dilation. How would this relieve chest pain?

Answer 1

A1: Nitroglycerin is a class of medication called vasodilators. It works by relaxing the blood vessels. The drug is administered as a tablet that is absorbed sublingually (below tongue) in case of anginal chest pain.

Mechanism Of Action

Angina is a type of chest pain caused by reduced blood flow to the heart it is often a symptom of coronary artery disease and is often described as angina pectoris.

Nitroglycerin forms free radical nitric oxide ( NO) which activates Guanylate cyclase there by resulting in an increase of Cyclic GMP in smooth muscle and other tissue, These events lead to dephosphorylation of myosin light chain and this in turn regulates the contractile state in smooth muscle and the end result is vasodilation.

As the patient has consumed nitroglycerin within few minutes (approximately 1 to 3 minutes) the above reaction will take place, which will lead to relaxation of vascular smooth muscle and thus will lead to dilation of both arterial and venous beds. Dilation of large veins promotes peripheral pooling of blood, decreases venous return to the heart and reduces left ventricular end diastolic pressure (Pre load). nitroglycerin also produces arteriolar relaxation and thus reducing peripheral vascular resistance and arterial pressure (after load). Thus nitroglycerin relives angina (chest pain) by causing coronary dilation and reducing preload and after load This causes increased blood flow in heart and will relive the chest pain