Adenosine

Question 1

class

Answer 1

antiarrythmic, endogenous nucleoside

Question 2

Mechanism of action

Answer 2

 Slows conduction time through AV node; can interrupt re-entrant pathways through the
AV node.
 Slows sinus rate.
 Larger doses decrease BP by decreasing peripheral resistance.

Question 3

indications and field use

Answer 3

 Conversion of supraventricular tachycardias with no known atrial fibrillation or atrial
flutter.
 Undifferentiated regular monomorphic wide-complex tachycardia

Question 4

contraindications

Answer 4

 Sick sinus syndrome, 2nd or 3rd degree AV blocks; except in patients with a functioning
ventricular pacemaker.
 Use cautiously in patients with known asthma (has precipitated acute bronchospasm).
 Patients on theophylline and related methylxanthines.
 Patients on dipyridamole (Persantine) or carbamazepine (Tegretol).
 Cardiac transplant patients are more sensitive to adenosine and require only a small dose
(relative).
 Known atrial fibrillation or atrial flutter.
 Pregnancy (no controlled studies)

Question 5

adverse reactions

Answer 5

CV: Transient dysrhythmias (systole, bardycardia, PVC’s) occur in 55% of patients
(none reported as irreversible). Palpitations, chest pressure, chest pain,
hypotension, transient hypertension; facial flushing, sweating.
Resp: Dyspnea, hyperventilation, tightness in throat, bronchospasm.
CNS: Lightheadedness, headache, dizziness, paresthesias, apprehension, blurred vision,
neck-back pain.
GI: Nausea, metallic taste.

Question 6

incompatibilities/drug interactions

Answer 6

 Adenosine is not blocked by Atropine.
 Theophylline and related methylxanthines (caffeine & theobromine-xanthine) in
therapeutic concentrations decrease effectiveness.

Dipyridamole (Persantine) & carbamazepine (Tegretol, Atretol) block uptake and
potentiate effects.

Question 7

adult dose

Answer 7

 Initial: 6 mg rapid IV bolus over 1-3 seconds
 Special administration procedure: Follow immediately with 20 ml normal saline flush.
IV site recommended is antecubital fossa (close to central circulation); use injection port
nearest hub of IV catheter; arm elevated during procedure; constant ECG monitoring.
 Repeat: If no response in 1-2 minutes (of each dose, respectively) may repeat 12 mg
utilizing the same procedure for the repeat dose.

Question 8

ped dose (Drug of choice for treating SVT in symptomatic infants and children)

Answer 8

 Initial: 0.1 mg/kg as a rapid IV bolus.
 Special administration procedure: Follow immediately with 2-3 ml normal saline flush.
Use injection port nearest the hub of IV catheter for procedure; constant ECG monitoring.
 Repeat: If no response, dose may be doubled 1 time (0.2 mg/kg) using same
administration procedure.
 Maximum single dose: Should not exceed 12 mg.
 Infants with SVT associated with shock: Adenosine may precede cardioversion if
vascular access is available, but cardioversion should not be delayed while IV access is
achieved.

Question 9

routes of admin

Answer 9

rapid IV push

Question 10

onset of action

Answer 10

seconds

Question 11

peak effects

Answer 11

seconds

Question 12

duration of action

Answer 12

10-12 seconds (1/2 life 5 seconds)

Question 13

AZ drug minimum

Answer 13

18 mg

Question 14

Special notes

Answer 14

 Dysrhythmias may recur (short half-life).
 Dysrhythmias appear in 55% of patients at conversion, lasting for a few seconds, usually require intervention.
 Second dose must be prepared and available.
 Check for crystallization in cold climates.