COMPARISON OF CALCIUM RETENTION MEASURED USING A RADIONUCLIDE METHOD AFTER ADMINISTRATION OF 1000 MG ELEMENTAL CALCIUM IN 2 DIFFERENT GALENIC FORMS, IN ONE OR 2 DOSES

A randomized, open, crossover, two-phase study was conducted to compar e body retention of calcium measured using a radionuclide method after acute oral administration of 1 000 mg elemental calcium in two differ ent galenic forms, in one or two doses. In the first phase of the stud y, which included 14 volunteers, the two treatments were one dissolve- in-the-mouth tablet of calcium carbonate in the morning and one in the evening (Orocal (R) 500 mg) (treatment Al) and one effervescent table t calcium carbonate (Cacit(R) 1000) (treatment B). In the second phase in 8 volunteers, treatment Al (Orocal(R) 500 mg) was compared to two tablets of the same preparation in a single dose (Orocal(R) 500 mg) (t reatment A2). Each treatment contained a tracing dose of Ca-47. Body r etention, expressed as the percentage of the total dose and measured s even and 14 days after each treatment, was significantly greater with Orocal(R) 500 mg than with Cacit(R) 1000 (24.21 +/- 3.38 versus 11.96 +/- 2.50 on day 7; 20.22 +/- 3.26 versus 9.67 +/- 2.56 on day 14; p < 0.001). Retention after administration of Orocal(R) 500 mg was slightl y better with two doses than with one dose (24.66 +/- 3.44 versus 21.3 2 +/- 7.63 on day 7; 20.19 +/- 3.28 versus 17.29 +/- 6.63 on day 14). Twenty-five per cent of the difference in calcium retention between tr eatments Al (Orocal(R) 500 mg) and B (Cacit(R) 1000) was ascribable to the dosing schedule difference and 75% to the differences in galenic characteristics.