On the pharmacological actions of a diuretic, fenquizone, with particular reference to its site of action

The pharmacological actions of a diuretic drug, fenquizone have been investigated and its effects compared with well characterized diuretics in rats, mice and rabbits. Changes in sodium and potassium excretion and urine volume were similar in magnitude and duration to those of the thiazide diuretics over dose range 0.05-100 mg kg-1. Free water clearance in rabbits was decreased indicating an action at the cortical diluting site in the nephron and since free water reabsorption was relatively unaffected it appears unlikely to have actions at Other sites. Calcium and phosphate excretion studies also suggested that the predominant effects are those occurring at the cortical diluting segment of the nephron. Additional parameters not affected by the drug were blood flow to the cortex and medulla of the kidney (and Other major organs), plasma glucose concentration and plasma urate concentration.