diltiazem + theophylline

Diltiazem + theophylline is a combination of two small molecule drugs, each with distinct mechanisms of action. Diltiazem is a non-dihydropyridine calcium channel blocker primarily used for cardiovascular conditions such as hypertension, angina, and certain arrhythmias. It works by inhibiting calcium influx into cardiac and vascular smooth muscle during depolarization, resulting in vasodilation and reduced cardiac workload[6]. Theophylline is a methylxanthine bronchodilator indicated for asthma, COPD, and other reversible obstructive airway diseases. Its mechanism involves phosphodiesterase inhibition (increasing cAMP), adenosine receptor antagonism (leading to bronchodilation), and histone deacetylase activation[7]. When combined, these drugs may be used in patients requiring both cardiovascular management (diltiazem) and bronchodilation (theophylline). However, co-administration can result in pharmacokinetic interactions; diltiazem inhibits hepatic metabolism of theophylline via cytochrome P450 enzymes, leading to increased serum concentrations of theophylline and potential toxicity[2][3][4][8].