Velocidad de disolución de diferentes preparados de calcio utilizados en clínica / Dissolution velocity of different calcium solutions used in clinics

RESUMO

Hydrochloric acid was added to destilled water in increasing amounts to obtain a final pH of 6.9, 3.0, 2.5, 2.0 and 1.5. Eighteen commercial calcium preparations were incubated in these solutions for 60 min and dissolution velocity was measured as the percentage of elemental calcium found in solution after this incubation period. Calcium carbonate preparations had a pH 1.5. Using the solution with pH 1.5 the dissolution velocity of different preparations varied widely from 56 to 100 percent. Calcium acetate, followed by calcium citrate and dicalcic phosphate were the salts in tablets with better dissolution velocities. Among powders and effervescent preparations, those containing calcium lactogluconate and citrate had the better dissolution velocities (95 to 115 percent), that were independent of the solution's pH. A studied preparation with integral bone had a very low dissolution velocity, not surpassing 33 mg of calcium per tablet. The dissolution velocity of different calcium carbonate preparations varies greatly and in conditions of achlorhydria, it is negligible. Calcium lactogluconate and citrate dissolution velocities are independent of the solution's pH