Adenosine (Adenocard®)
endogenous nucleotide
Adenosine is primarily formed from the breakdown product of adenosine triphosphate (ATP). Both compounds are found in every cell of the human body, and have a wide range of metabolic roles. Its actions in the AV node are thought to act through stimulation of specific adenosine receptors. Adenosine slows those tachycardias associated with the AV node (i.e. AV Node Re-entry Tachycardias) by decreasing conductivity through the node. Specifically, activation of A1 receptors in the AV node activate an inward potassium channel and inactivation of inward slow calcium channels that result in membrane hyperpolarization. This decreases the speed of AV node conduction and increases the AV node refractory period.
Although there are adenosine receptors in most every cell, includes those of the sinus pacemakers, there is no clinical effect of the drug on tachycardias originating outside the AV node such as sinus tachycardia, atrial fibrillation or atrial flutter.
within 30 seconds
10 seconds
Conversion of PSVT (including those associated with WPW syndrome) to sinus rhythm
Second or third degree AV block, or sick sinus syndrome
Hypersensitivity to adenosine
Lightheadedness, hypotension, paresthesia, shortness of breath, headache, transient periods of sinus bradycardia and ventricular ectopy, palpitations, chest pain, nauseua
Methylxanthines (ie caffeine and theophylline) antagonize the action of adenosine.
Dipyridamole potentiates the effect of adenosine; you may need to reduce dose of adenosine
Carbamazepine may potentiate the AV-nodal blocking effect of adenosine, therefore the adenosine dose may need to be decreased.
Paranteral for IV injection
3 mg/ml in 2 ml flip-top vials
Initial : 6 mg rapid IV bolus over 1-3 second, followed immediately by a 20 ml saline flush.
Repeat if no change after 1-2 minutes at 12 mg in same manner. Repeat again at 12 mg after 1-2 mg
Initial dose 0.1mg/kg, may be doubled once if no effect. Max single dose 12 mg. Follow immediately with 2-3ml saline flush
Pregnancy Safety: Class C
A brief period of asystole (up to 15 seconds) following conversion, followed by NSR is common after rapid administration
Patients on theophylline may require larger doses
Cardiac tansplant patients may require only a small dose
May produce bronchoconstriction in patient with asthma or bronchopulmonary disease