Mercurial diuretics now form a necessary part in the treatment of congestive heart failure. This is particularly true in the case of those patients who no longer show any response to digitalis therapy. Attention should be called to the fact that mercurial diuretics act on the tubules of the kidney interfering there with the reabsorption of water and sodium chloride. The effect on the heart is, therefore, secondary. The fall in venous pressure may not occur for several hours after diuresis has begun from the intravenous injection of a mercurial, whereas the venous pressure begins to fall within ten minutes after the intravenous administration of a rapidly acting glycoside such as ouabain.
All three of the commonly used mercurial diuretics in this country contain theophylline. In mercurophylline injection ("mercuzanthin") the theophylline is in molar equivalent amounts with the mercurial compound. In mersalyl and theophylline ("salyrgan-theophylline") and in meralluride sodium solution