Theophylline Interactions

Caffeine and theophylline are closely related methylxanthines that share the CYP1A2 metabolic pathway and compete for the same adenosine receptors. Concurrent use can raise theophylline levels and add pharmacodynamically to cause tachycardia, tremor, nausea, seizures or arrhythmias.

Polycyclic aromatic hydrocarbons in tobacco smoke induce CYP1A2, increasing theophylline clearance by 58-100% and shortening its half-life by roughly 63%. Smokers often need 1.5-2 times the usual theophylline dose, and abrupt cessation can rapidly produce toxic levels.