I.V. ADENOSINE HAS BEEN EFFECTIVELY ADMINISTERED IN THE PRESENCE OF OTHER CARDIOACTIVE DRUGS, SUCH AS QUINIDINE, BETA-ADRENERGIC BLOCKING AGENTS, CALCIUM BLOCKING AGENTS, AND ANGIOTENSIN CONVERTING ENZYME INHIBITORS. COMBINED USE WITH DIGOXIN AND VERAPAMIL ASSOCIATED WITH VENTRICULAR FIBRILLATION IS POSSIBLE. CAFFEINE,THEOPHYLLINE AND OTHER XANTHINES ARE INHIBITORS .DIPYRIDAMOLE INHIBITS ADENOSINE UPTAKE AND THEREFORE MAY POTENTIATE ITS ACTION. RISK OF AV BLOCK IS INCREASED IF ADENOSINE IS CONCURRENTLY ADMINISTERED WITH OTHER DRUGS THAT SLOW AV CONDUCTION.