Adenosine

It is one of the naturally occurring nucleoside.
Action:
It causes a reduction in conduction velocity. It causes an increased refractory period and reduces automaticity in the AV node.

Pharmacokinetics:
Its duration of action is short. Its half life is approximately 10 seconds.

Therapeutic uses:
Acute supraventricular tachycardia (IV administration)

Adverse effects:
Flushing, chest pain, dyspnea, hypotension