MONOSORB XL is a brand name for a medication that contains the active ingredient isosorbide mononitrate, which is primarily used in the treatment of angina pectoris, a condition characterized by chest pain or discomfort due to coronary heart disease. As an extended-release formulation, MONOSORB XL is designed to release the medication slowly over time, allowing for once-daily dosing. Isosorbide mononitrate belongs to a class of drugs known as nitrates, which work by relaxing and widening blood vessels. This action helps to increase blood flow to the heart muscle and reduces its workload, thereby preventing angina attacks. It is important for patients to follow their healthcare provider's instructions when using MONOSORB XL to ensure its effectiveness and to minimize potential side effects.