5 WARNINGS AND PRECAUTIONS
5.1 Cardiac Arrest, Ventricular Arrhythmias, and Myocardial Infarction
Fatal and nonfatal cardiac arrest, sustained ventricular tachycardia (requiring resuscitation), and myocardial infarction have occurred following adenosine infusion. Avoid use in patients with symptoms or signs of acute myocardial ischemia, for example, unstable angina or cardiovascular instability; these patients may be at greater risk of serious cardiovascular reactions to adenosine injection. Appropriate resuscitative measures should be available [see Overdosage (10)].
5.2 Sinoatrial and Atrioventricular Nodal Block
Adenosine injection exerts a direct depressant effect on the SA and AV nodes and may cause first-, second- or third-degree AV block, or sinus bradycardia. In clinical trials, approximately 6% of patients developed AV block following adenosine injection administration (first-degree heart block developed in 3%, second-degree in 3%, and third-degree in 0.8% of patients) [see Clinical Trials Experience (6.1)].
Use adenosine injection with caution in patients with pre-existing first-degree AV block or bundle branch block. Do not use in patients with high-grade AV block or sinus node dysfunction (except in patients with a functioning artificial pacemaker). Discontinue adenosine injection in any patient who develops persistent or symptomatic high-grade AV block.
5.3 Bronchoconstriction
Adenosine injection administration can cause dyspnea, bronchoconstriction, and respiratory compromise. Adenosine injection should be used with caution in patients with obstructive lung disease not associated with bronchoconstriction (e.g., emphysema, bronchitis). Do not use in patients with bronchoconstriction or bronchospasm (e.g., asthma). Discontinue adenosine injection in any patient who develops severe respiratory difficulties. Resuscitative measures should be available prior to adenosine injection administration [see Clinical Trials Experience (6.1), Overdosage (10), and Clinical Pharmacology (12.2)].
5.4 Hypotension
Adenosine injection is a potent peripheral vasodilator and can induce significant hypotension. The risk of serious hypotension may be higher in patients with autonomic dysfunction, hypovolemia, stenotic valvular heart disease, pericarditis or pericardial effusions, or stenotic carotid artery disease with cerebrovascular insufficiency. Discontinue adenosine injection in any patient who develops persistent or symptomatic hypotension.
5.5 Cerebrovascular Accident
Hemorrhagic and ischemic cerebrovascular accidents have occurred. Hemodynamic effects of adenosine injection including hypotension or hypertension can be associated with these adverse reactions. [see Warnings and Precautions (5.4) and (5.9)].
5.6 Seizures
New-onset or recurrence of convulsive seizures has occurred following adenosine injection. Some seizures are prolonged and require emergent anticonvulsive management. Aminophylline may increase the risk of seizures associated with adenosine injection. Methylxanthine use is not recommended in patients who experience seizures in association with adenosine injection administration [see Overdosage (10)].
5.7 Hypersensitivity, including Anaphylaxis
Dyspnea, throat tightness, flushing, erythema, rash, and chest discomfort have occurred. Symptomatic treatment may be required. Have personnel and appropriate treatment available. Resuscitative measures may be necessary if symptoms progress. [see Post-Marketing Experience (6.2)].
5.8 Atrial Fibrillation
Adenosine injection can cause atrial fibrillation in patients with or without a history of atrial fibrillation. Atrial fibrillation typically began 1.5 to 3 minutes after initiation of adenosine injection, lasted for 15 seconds to 6 hours, and spontaneously converted to normal sinus rhythm [see Post-Marketing Experience (6.2)].
5.9 Hypertension
Adenosine injection can induce clinically significant increases in systolic and diastolic blood pressure. Most increases resolved spontaneously within several minutes, but in some cases, hypertension lasted for several hours [see Clinical Trials Experience (6.1)].