Adenosine – Class IIe

Adenosine – Class IIe

Adenosine is a class IIe antiarrhythmic agent as per the Modernized Classification of Cardiac Antiarrhythmic Drugs [1]. Autonomic inhibitors and activators constitute new class II.

Adenosine is an adenosine A1 receptor activator, activating A1 receptors in supraventricular tissue (sinoatrial node, atrial tissue and atrioventricular node). It activates G protein–coupled inward rectifying K⁺ channels and I_KAdo.

Adenosine hyperpolarizes the sinoatrial node and shortens the action potential durations in atrial and AV node tissue. It reduces early afterdepolarization (EAD)/ delayed afterdepolarization (DAD) triggered activity.

Adenosine is useful in the acute termination of AV nodal tachycardia and cAMP-mediated triggered ventricular tachycardias. Another role is in the differentiation of sinus from atrial tachycardia.

Adenosine can precipitate bronchospasm in asthmatics. It is thought to be due to adenosine binding to specific purino receptors in the mast cells of the lungs leading to release of mediators which cause bronchoconstriction and asthma [2].

References

1. Ming Lei, Lin Wu, Derek A Terrar, Christopher L-H Huang. Modernized Classification of Cardiac Antiarrhythmic Drugs. Circulation. 2018 Oct 23;138(17):1879-1896.
2. S B Rao. Adenosine and its role in asthma. Indian J Clin Biochem. 2001 Jul;16(2):140-4.