Diuretic induced hypokalaemia: relationship to dosage interval and plasma aldosterone.

Abstract

Plasma potassium and aldosterone responses to 9 days treatment with hydrochlorothiazide (100 mg/ day) alone or in combination with spironolactone (100 mg/day), prescribed once daily or in doses 12 h apart, were examined in a double-blind, crossover study in twelve healthy subjects. Plasma potassium concentrations were lower when the drugs were administered 12 h apart (P < 0.01). Spironolactone attenuated significantly hydrochlorothiazide induced hypokalaemia-mean rise in plasma potassium, 0.36 mmol/l (P < 0.001). The increase in plasma aldosterone was greater following combination therapies (P < 0.001), but there were no significant differences between once daily and twice daily regimens. We conclude that plasma potassium concentration is better maintained when diuretics are given once daily and that this is not related closely to differences in plasma aldosterone responses.

Metabolic Effects of Diuretics

“…At standard doses the mean fall in serum potassium level with a loop diuretic is approximately half that observed with a thiazide [14], Loop diuretics also appear to have a smaller effect on glucose homoeostasis. It is likely that these differ ences between diuretics are explained by dif ferences in the duration of their natriuretic action, and it is of interest in this respect that twice daily regimens cause more marked bio chemical disturbance than the equivalent dose taken once daily [ 15].…”