methylxanthine
2 interactions related to methylxanthine
caffeine + theophylline
Caffeine and theophylline are closely related methylxanthines that share the CYP1A2 metabolic pathway and act on the same adenosine receptors. Taking them together can slow theophylline clearance and add to its stimulant and cardiovascular effects, which matters because theophylline has a very narrow safety margin.
caffeinetheophyllinemethylxanthineasthmacopdcyp1a2narrow therapeutic indextoxicity
chocolate + adenosine
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.
chocolateadenosineregadenosoncardiac stress testcaffeinetheobrominemethylxanthineSVTnuclear stress test