Adenosine is a Class V Antiarrhythmic Agent used to treat Supraventricular Tachycardia (SVT). This drug has a VERY short half-life and must be administered in a particular way to work effectively.
What is Adenosine?
Let’s go back to our Organic Chemistry days.
(GIPHY)
Remember DNA? DNA is made up of Nucleic Acids which is made up of Nucleotides. Nucleotides are made up of 2 of 4 purine nucleobases that are bound together.
- Adenine
- Thymine
- Guanine
- Cytosine
(Source)
When you add Adenine to a ribose sugar you get Adenosine.
Side Note: When you add three phosphate groups to Adenosine you get Adenosine Triphosphate (ATP)… You know, good ole ATP that gives your cells ENERGY.
How does Adenosine Work?
Adenosine (by itself and not as ATP) binds to purinergic receptors in vascular smooth muscle cells, causing relaxation, thus slowing the heart rate down. Adenosine also binds to the A-1 receptors in the Sinoatrial (SA) Node inhibiting the pacemaker current, again slowing the heart rate down. Finally, adenosine will bind to the nerve terminals, decreasing the release of norepinephrine which reduces conduction velocity, especially at the Atrioventricular (AV) Node. Sometimes the reduction of electrical activity at the AV node can cause AV block.
Adenosine has a very short half-life (less than 10 seconds) so the effects slow down the heart enough to reset the electrical rhythm back to normal sinus rhythm.
How to Administer Adenosine
When a patient is in Paroxysmal Supraventricular Tachycardia or having Wolff-Parkinson-White Syndrome, you will want to administer Adenosine in a rapid bolus to slow down the heart to allow the electrical rhythm to reset.
It comes in 3mg/mL concentrations with 2 mL in the vial. The first dose you give is 6 mg or 2 mL. If that does not work then you re-dose with 12 mg instead of 6 mg.
So the best way to give Adenosine is in a large bore IV located at or above the antecubital but not below the wrist. If possible, you will want to push the medication with a stopcock attached to the hub of the catheter rather than through a J-loop or any other extended IV tubing. Pictured below is a stopcock with 2 mL of Adenosine on one attachment and a 10 cc flush on the other attachment.
This requires two people to administer. One person to push the meds and one person to flip the stopcock switch.
Nursing considerations while giving Adenosine
- Have the patient on the cardiac monitor, including Pulse ox and BP cuff to document continuous vitals during the administration of adenosine.
- Also, have a 12 lead EKG attached to capture a rhythm strip before, during and after the administration of adenosine.
- Lastly, have the AED pads on the patient in case the electrical activity is reset to a life-threatening arrhythmia.
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