Paracetamol: Accelerated absorption w/ metoclopramide or domperidone. Reduced absorption w/ cholestyramine. Increased susceptibility to harmful liver effects w/ drugs for convulsion (eg, phenobarb, phenytoin, carbamazepine). Increased in INR w/ warfarin. Increased risk of liver toxicity w/ alcohol (eg, ethanol) or INH. Possibility of severe hypothermia w/ phenothiazine. Decreased clearance & increased effects w/ probenecid pre-treatment. Caffeine: Weakened vasodilating effect of substances used for myocardial imaging (eg, adenosine, dipyridamole). Antagonistic effect w/ sedatives & tranquilizers (eg, diazepam, zolpidem). May increase action of phenylpropanolamine in increasing heart rate. Competitively inhibits clozapine metabolism. Slight to moderate increase in serum lithium carbonate levels. Increased stimulant effects w/ MAOIs (eg, phenelzine, moclobemide, selegiline). Reduced clearance & increased effects w/ methoxsalen & pipemidic acid. Increased BP w/ levothyroxine. Increased clearance & decreased effects w/ phenytoin. Increased blood sugar & lactate conc w/ ephedrine.