diuretic /dī′yo͝oret″ik/ , 1. adj., (of a drug or other substance) tending to promote the formation and excretion of urine. 2. n., a drug that promotes the formation and excretion of urine. The more than 50 diuretic drugs available in the United States and Canada are classified by chemical structure and pharmacological activity into groups: carbonic anhydrase inhibitors, loop diuretics, mercurials, osmotics, potassium-sparing diuretics, and thiazides. A diuretic medication may contain drugs from one or more of these groups. Diuretics are prescribed to reduce the volume of extracellular fluid in the treatment of many disorders, including hypertension, congestive heart failure, and edema. The specific drug to be prescribed is selected according to the action desired and the patient’s physical status. Hypersensitivity to sulfonamides prohibits use of many diuretic drugs, and diabetes mellitus may be aggravated by thiazide medications. Thus the presence of a particular condition may prohibit the use of a particular agent. Several adverse reactions, including hypovolemia and electrolyte imbalance, are common to all diuretics. Mercurial diuretics are rarely used because of their nephrotoxicity, and carbonic anhydrase inhibitors have only weak diuretic activity.
