Potentiates adrenoceptor & stimulates action w/ catecholamines eg, epinephrine & isoproterenol. Decrease K level & aggravates CV effects w/ xanthine derivatives eg, theophylline, aminophylline, diprophylline; corticosteroids (eg, betamethasone, prednisolone & hydrocortisone Na succinate) & diuretics (eg, furosemide).