Theophylline can inhibit the effects of
adenosine infusions used in conjunction with radionuclide myocardial imaging.
Theophylline may antagonise the effect of
adenosine when used to treat supraventricular arrhythmias.
Theophylline, aminophylline and other xanthines should be avoided for 24 hours before using an
adenosine infusion for radionuclide myocardial imaging.
Adenosine bolus injections for the termination of paroxysmal supraventricular tachycardia may still be effective in patients taking xanthines. The usual dose schedule should be followed. However, note that
adenosine has induced
bronchospasm and it has been suggested that
adenosine should be avoided in patients with
asthma, and used cautiously in those with obstructive
pulmonary disease. Xanthines, such as
intravenous aminophylline, may be used to terminate any persistent adverse effects of
adenosine infusions given for myocardial imaging.