Ranolazine - sold under brand names Ranexa and others - is a prescription-only medication used to treat anginaplugin-autotooltip__plain plugin-autotooltip_bigMicrovascular angina

Microvascular angina ( previously known as Cardiac Syndrome X ) is a form of angina (chest pain) associated with insufficient blood flow to the heart (and some other organs/regions) but in patients who have normal coronary angiograms..

It was approved in the US in 2006, where it's now prescribed more than one million times per year.

Although it's known that Ranolazine inhibits persistent or late inward sodium current in the heart muscles, the exact mechanism of action is unknown.

Exact mechanism of antianginal action not fully elucidated; may involve the shifting of adenosine triphosphate (ATP) production away from fatty acid oxidation (i.e., partial inhibition of fatty acid oxidation) in favor of more oxygen-efficient glucose oxidation, especially when free fatty acid concentrations are elevated (e.g., during ischemia), leading to reduced oxygen demand and symptoms of ischemia without affecting cardiac work.

Source : Drugs.com