This study was conducted to compare the value of an older formulation of
potassium-magnesium citrate (K4MgCit2) with newer formulations (K3MgHCit2 and K5MgCit2Cl) with respect to the correction of
thiazide-induced
hypokalemia and
magnesium loss, alkalinizing effect, and citraturic action. Sixty-two healthy volunteers first took
hydrochlorothiazide 50 mg/day. After 3 weeks of
thiazide treatment (or earlier if
hypokalemia developed), they were randomized to take one of three drugs for 3 weeks while continuing
thiazide: K4MgCit2 (49 mEq K, 25 mEq Mg, and 74 mEq
citrate/day), K3MgHCit2 (49 mEq K, 33 mEq Mg, and 98 mEq
citrate/day), and K5MgCit2Cl (49 mEq K, 20 mEq Mg, 10 mEq Cl and 59 mEq
citrate/day). Outcome measures were changes in serum
potassium and
magnesium, and urinary
potassium,
magnesium, pH, and
citrate. The three drugs were equally effective in correcting
thiazide-induced
hypokalemia. K3MgHCit2 and K4MgCit2 produced a small but significant increase in serum
magnesium concentration, whereas K5MgCit2Cl did not. Although all three supplements significantly increased urinary pH and
citrate, these effects were more marked with K3MgHCit2 and K4MgCit2 than with K5MgCit2. All three supplements were generally well tolerated, with the lowest side effect profile obtained with K4MgCit2. The new formulation of K3MgHCit2 exerts similar correction of
thiazide-induced
hypokalemia and
magnesium loss, and enhancement of urinary pH and
citrate, compared with the older K4MgCit2. However, it is less well tolerated. The new formulation of K5MgCit2Cl does not avert
magnesium loss, and has less prominent alkalinizing and citraturic effects than the older preparation.