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A comparison of the potassium and magnesium‐sparing properties of amiloride and spironolactone in diuretic‐treated normal subjects.
Author(s) -
Murdoch DL,
Forrest G,
Davies DL,
McInnes GT
Publication year - 1993
Publication title -
british journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.216
H-Index - 146
eISSN - 1365-2125
pISSN - 0306-5251
DOI - 10.1111/j.1365-2125.1993.tb04153.x
Subject(s) - amiloride , spironolactone , diuretic , magnesium , potassium , pharmacology , medicine , sodium , chemistry , endocrinology , aldosterone , organic chemistry
1. The relative potencies of amiloride (5 and 20 mg) and spironolactone (25 and 100 mg) for plasma and erythrocyte electrolytes were investigated in a double‐blind, randomised, balanced, crossover study in 12 normal men treated concomitantly with hydrochlorothiazide 100 mg daily for 1 week. 2. Participants satisfied an a priori requirement for a fall in plasma potassium concentration of at least 0.5 mmol l‐1 after 7 days of treatment with hydrochlorothiazide alone. 3. After hydrochlorothiazide alone, plasma potassium and sodium concentrations fell (P < 0.001). There were associated reductions in erythrocyte sodium (P < 0.01). Plasma magnesium concentration did not change, although erythrocyte magnesium decreased (P < 0.001). 4. Both amiloride and spironolactone attenuated the thiazide‐induced fall in plasma potassium (relative potency, amiloride:spironolactone 10:1, 95% confidence interval 6.3‐16.2:1). Amiloride but not spironolactone was associated with a dose‐related increase in plasma magnesium; a relative potency estimation was precluded. There was little evidence of influences of amiloride or spironolactone on erythrocyte electrolytes. 5. On a weight basis, amiloride is ten times more potent than spironolactone as a potassium‐sparing agent in diuretic‐treated subjects but neither agent had major effects on erythrocyte potassium. The drugs may have divergent actions on magnesium handling; hydrochlorothiazide alone had no influence on plasma magnesium.