Bioavailability, biodistribution and toxicity of Biocal (TM) a new calciumsource. Comparative studies in rats

The purpose of this study is to determine the bioavailability, biodistribut ion and toxicity of Biocal(TM), a new calcium source. Biocal(TM) is a calci um gluconate stabilized with glycine. A comparative study of this compound versus calcium gluconate was performed in Sprague-Dawley rats. Bioavailabil ity studies were carried out by the labeling of both compounds with Ca-45. We administered a dose of 30 mg of Ca per kg of body weight p.o. to two gro ups of 7 male adult rats each. The urine elimination of the Ca-45, expresse d as total accumulated percentage of Ca-45 activity in urine (Ae(infinity)) , between the rats that received Biocal(TM) (Ae(infinity) = 2.436+/-1.337 % ) and the rats that received calcium gluconate (Ae(infinity) = 1.241+/-0.47 3 %) were found to be statistically different (p<0.05). Biodistribution stu dies showed that the calcium from Biocal(TM) follows the same metabolic pat hway as calcium from calcium gluconate. Values of radioactivity concentrati on of 97.1+/-1.3% and 98.7+/-1.6% were found in bone for Biocal(TM) and cal cium gluconate, respectively. Toxicity studies of Biocal(TM) were carried o ut with 60 female and 60 male rats. The values of oral LD50 for female rats was 13.5 g/kg with a lower limit of 12.8 g/kg and upper limit of 14.3 g/kg . In the case of male rats the LD50 was 13.0 g/kg with a lower limit of 12. 2 g/kg and upper limit of 13.9 g/kg. These values are higher with regard to the oral LD50 for calcium gluconate (10 g/kg). Our results demonstrate tha t calcium from Biocal(TM) has a higher bioavailability with the same metabo lic behavior than calcium from calcium gluconate. The value of oral LD50 sh ows that the toxicity of Biocal(TM) is lower than that of the calcium gluco nate. Therefore we conclude that Biocal(TM) has adequate properties to be c onsidered as a promissory calcium compound to be used as dietary supplement or for food fortification. (C) 1999 Elsevier Science Inc.