Mode of action of conventional and potassium-sparing diuretics--aspects with relevance to Mg-sparing effects. Review of the present state of the art and recent findings.

The sites and modes of action of five groups of diuretics within the nephron, and their effects on magnesium excretion are outlined. More than 60% of the glomerularly filtered magnesium is reabsorbed in the loop of Henle. Hence, the loop diuretics induce a strong magnesium excretion. The benzothiadiazine diuretics increase magnesium excretion only moderately. In contrast, the potassium-sparing diuretics amiloride and triamterene, as well as the aldosterone antagonists, increase magnesium reabsorption and therefore may be designated as magnesium-conserving diuretic drugs. The possible modes of action of this property are discussed.