When it is administered intravenously, adenosine causes transient heart block in the atrioventricular (AV) node. This is mediated via the A1 receptor, inhibiting adenylyl cyclase, reducing cAMP and so causing cell hyperpolarization by increasing K+ efflux via inward rectifier K+ channels, subsequently inhibiting Ca2+ current. It also causes endothelial-dependent relaxation of smooth muscle as is found inside the artery walls. This causes dilation of the "normal" segments of arteries, i.e. where the endothelium is not separated from the tunica media by atherosclerotic plaque. This feature allows physicians to use adenosine to test for blockages in the coronary arteries, by exaggerating the difference between the normal and abnormal segments.
The administration of adenosine also reduces blood flow to coronary arteries past the occlusion. Other coronary arteries dilate when adenosine is administered while the segment past the occlusion is already maximally dilated. This leads to less blood reaching the ischemic tissue, which in turn produces the characteristic chest pain.
In individuals with supraventricular tachycardia (SVT), adenosine is used to help identify and convert the rhythm.
Certain SVTs can be successfully terminated with adenosine. This includes any re-entrant arrhythmias that require the AV node for the re-entry, e.g., AV reentrant tachycardia (AVRT), AV nodal reentrant tachycardia (AVNRT). In addition, atrial tachycardia can sometimes be terminated with adenosine.
Fast rhythms of the heart that are confined to the atria (e.g., atrial fibrillation, atrial flutter) or ventricles (e.g., monomorphic ventricular tachycardia) and do not involve the AV node as part of the re-entrant circuit are not typically converted by adenosine. However, the ventricular response rate is temporarily slowed with adenosine in such cases.
Because of the effects of adenosine on AV node-dependent SVTs, adenosine is considered a class V antiarrhythmic agent. When adenosine is used to cardiovert an abnormal rhythm, it is normal for the heart to enter ventricular asystole for a few seconds. This can be disconcerting to a normally conscious patient, and is associated with angina-like sensations in the chest.
Side effects of adenosine include:
Post marketing side effects of adenosine reported include:
Dosage Considerations – Should be Given as Follows:
Paroxysmal Supraventricular Tachycardia
Stress Testing (Diagnostic)
If your doctor has directed you to use this medication, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider or pharmacist first.
Adenosine has no known severe interactions with other drugs.
Adenosine has no known serious interactions with other drugs.
Moderate interactions of adenosine include:
Mild interactions of adenosine include:
Alclofenac is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store alclofenac in the bathroom or the freezer. There may be different brands of alclofenac that may have different storage needs. It is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.
Before using this drug, tell your doctor if: