Theobromine, occurring in chocolate to the extent of 0.3 to 2 per cent., and theophylline, which occurs in minute quantities in tea leaves, but is manufactured synthetically for the market, are isomeric dimethylxanthines.

Theobromine stimulates both cardiac and voluntary muscles to some extent, and has the diuretic power of caffeine. But it is preferred as a diuretic because it lacks the undesirable central effects. For, having no vasoconstrictor action and but little stimulating effect upon the brain, it may be given in much larger doses without the production of wakefulness. The dose is 10 grains (0.6 gm.), given in capsule or powder three or four times a day. As it is insoluble and but slowly absorbed, its soluble combination with sodium salicylate, theobromine sodio-salicylate, known also by the proprietary name, diuretin, is preferred. Its dose is twice that of theobromine. We have many times noted a rise to between 200 and 300 ounces in the urine flow of dropsical patients after theobromine or diuretin. Christian says that this is an effect seen in cardiac dropsy rather than renal dropsy, but the author has seen it also in true kidney cases. In one recent kidney case with high blood-pressure, retinal changes, low phthalein output and low Ambard urea coefficient, the urine reached the phenomenal amount of 300 ounces in twenty-four hours; and the output continued high during seven days' administration of the drug.

Theophylline (theocine) has the same action and dose, but it is more irritating to the stomach, so that nausea is not infrequent, and it has some of the central effects of caffeine (Thomas). Theocin-acet-sodium is a soluble salt of this alkaloid. In the author's experience both mouth and intravenous doses have resulted in active diuresis. Dose, 7 1/2 grains (0.5 gm.), three or four times a day.