Adenosine Interactions

Caffeine and theobromine from chocolate are competitive antagonists at A1 and A2A adenosine receptors. When intravenous adenosine or regadenoson is used for a cardiac stress test, or adenosine is used to terminate supraventricular tachycardia, recent methylxanthine intake can blunt the drug's effect and produce a falsely normal stress test or a failure to convert the arrhythmia.

Nicotine produces sympathomimetic cardiovascular effects (faster heart rate, higher blood pressure, peripheral vasoconstriction) that can complicate the periprocedural setting in which intravenous adenosine is used for supraventricular tachycardia or pharmacologic cardiac stress testing. Direct interference with adenosine itself is mechanistic and largely shown in animal models; the better-documented antagonist that smokers commonly co-ingest is caffeine.