Adelseril, also known as adenosine, is a medication primarily used to treat certain types of supraventricular tachycardia, a condition characterized by an abnormally fast heart rate. It works by slowing down the electrical conduction in the heart, which can help restore a normal rhythm. Adenosine is typically administered intravenously in a clinical setting and has a very short half-life, requiring careful monitoring during its use. Additionally, it may naturally occur in the body and plays a role in various physiological processes.