Adenosine Interactions

Caffeine and theobromine from chocolate are competitive antagonists at A1 and A2A adenosine receptors. When intravenous adenosine is used for cardiac stress testing or to terminate supraventricular tachycardia, recent methylxanthine intake can blunt its effects and lead to a falsely negative test or failure to convert the arrhythmia.

Nicotine produces sympathomimetic cardiovascular effects (increased heart rate, blood pressure, peripheral vasoconstriction) and disrupts adenosine A2A receptor-mediated reflex cardiac control, which can blunt or interfere with the diagnostic and therapeutic actions of intravenous adenosine used for supraventricular tachycardia or cardiac stress testing.