THE EFFECT OF VARYING MOLAR RATIOS OF POTASSIUM-MAGNESIUM CITRATE ON THIAZIDE-INDUCED HYPOKALEMIA AND MAGNESIUM LOSS

This study was conducted to compare the value of an older formulation of potassium-magnesium citrate (K(4)MgCit(2)) with newer formulations (K(3)MgHCit(2) and K(5)MgCit(2)Cl) with respect to the correction of t hiazide-induced hypokalemia and magnesium loss, alkalinizing effect, a nd citraturic action. Sixty-two healthy volunteers first took hydrochl orothiazide 50 mg/day. After 3 weeks of thiazide treatment (or earlier if hypokalemia developed), they Mere randomized to take one of three drugs for 3 weeks while continuing thiazide: K(4)MgCit(2) (49 mEq K, 2 5 mEq Mg, and 74 mEq citrate/day), K(3)MgHCit(2) (49 mEq K, 33 mEq Mg, and 98 mEq citrate/day), and K(5)MgCit(2)Cl (49 mEq K, 20 mEq Mg, 10 mEq CI and 59 mEq citrate/day). Outcome measures were changes in serum potassium and magnesium, and urinary potassium, magnesium, pH, and ci trate. The three drugs were equally effective in correcting thiazide-i nduced hypokalemia. K(3)MgHCit(2) and K(4)MgCit(2) produced a small bu t significant increase in serum magnesium concentration, whereas K(5)M gCit(2)Cl did not. Although all three supplements significantly increa sed urinary pH and citrate, these effects were more marked with K(3)Mg HCit(2) and K(4)MgCit(2) than with K(5)MgCit(2)Cl. All three supplemen ts were generally well tolerated with the lowest side effect profile o btained with K(4)MgCit(2). The new formulation of K(3)MgHCit(2) exerts similar correction of thiazide-induced hypokalemia and magnesium loss , and enhancement of urinary pH and citrate, compared with the older K (4)MgCit(2). However, it is less well tolerated. The new formulation o f K(5)MgCit(2)Cl does not avert magnesium loss, and has less prominent alkalinizing and citraturic effects than the older preparation. (C) 1 998 The American College of Clinical Pharmacology.