Description: Adenosine or adenosine derivatives play many important biological roles in addition to being components of DNA and RNA. Adenosine itself is a neurotransmitter. Indication : Used as an initial treatment for the termination of paroxysmal supraventricular tachycardia (PVST), including that associated with accessory bypass tracts, and is a drug of choice for terminating stable, narrow-complex supraventricular tachycardias (SVT). Mechanism of action Adenosine slows conduction time through the AV node and can interrupt the reentry pathways through the AV node, resulting in the restoration of normal sinus rhythm in patients with paroxysmal supraventricular tachycardia (PSVT), including PSVT associated with Wolff-Parkinson-White Syndrome. This effect may be mediated through the drug's activation of cell-surface A1 and A2 adenosine receptors. Adenosine also inhibits the slow inward calcium current and activation of adenylate cyclase in smooth muscle cells