Abosorption of Calcium Salt

» The type of calcium salt used in calcium/vitamin D₃ preparations may affect the gastrointestinal absorption of calcium from the preparations

» One of the distinguishing features between the Calcia portfolio and products manufactured by some of the main competitors is the type of calcium salt used. The form of calcium contained in a product should therefore be taken into consideration if patients are to get maximum benefit from their treatment

» The Calcia Calcium/vitamin D₃ portfolio contains calcium carbonate; the typical absorption rate of calcium from calcium carbonate is in the range 20-40%, depending on the dose of calcium ingested and the individual physiological status

» Ekman et al carried out two separate crossover studies to compare the intestinal absorption of calcium from Calcia tablets with that from effervescent calcium lactogluconate/carbonate tablets, and calcium chloride solution, using the whole body retention and excretion of ⁴⁷Ca¹

» The Calcia tablet showed a significantly greater mean minimum absorption of calcium (25.6% in experiment 1; 22.8% in experiment 2) than calcium administered as effervescent calcium lactogluconate/carbonate tablets (16.9%) (p<0.05), but was similar to calcium chloride solution (24.7%)¹

» Deroisy et al compared the acute changes in parathyroid hormone (PTH) concentrations following oral administration of a Calcia chewable tablet, gluconolactate/carbonate water-soluble sachet, effervescent citrate tablet, pidolate/carbonate water-soluble sachet, ossein-hydroxyapatite complex tablets for swallowing and placebo²

» Calcia tablets (AUC=4705 pg/ml x min) and calcium citrate (AUC=4769 pg/ml x min) induced a significantly greater decrease in PTH levels compared with the others, (AUC ranged from 5193 to 6070 pg/ml x min) (p<0.05 for all comparisons)²

» These differences in PTH suppression may have significant implications for their clinical use as preventative or curative treatments for osteoporosis²

¹ Ekman M et al. Comparative absorption of calcium from carbonate tablets, lactogluconate/carbonate effervescent tablet, and chloride solution. Bone 1991; 12: 93-97.

² Deroisy R et al. Acute changes in serum calcium and parathyroid hormone circulating levels induced by the oral intake of five currently available calcium salts in healthy male volunteers. Clin Rheumatol 1997; 16: 249-253.

» Micheletti & Zartarian carried out a randomised, open, crossover study to compare the body retention of calcium after acute oral administration of1000 mg elemental calcium in two different formulations. They found that the mean calcium retention was significantly higher from one Calcia tablet given twice daily (2 x 500 mg Ca) than that from one dose of the effervescent tablet (1 x 1000 mg Ca) after 7 days (p<0.001). Also, there was slightly better calcium retention when one Calcia tablet was administered morning and evening, compared with two of the same tablets taken as a single dose in the morning, though the difference was not statistically significant¹

» Jiexiong et al compared the calcium absorption from two different tablets of calcium carbonate and vitamin D following a single oral dose; a significant increase in calcium excretion was found during all periods of supplementation compared with baseline; this was similar for both tablets²

» Tfelt-Hansen & Torring measured calcium absorption from Calcia tablets (with or without vitamin D₃) in a prospective, randomised, placebo-controlled, blinded crossover study. There was no difference between the two calcium treatments, which both had a higher 24-hour urinary calcium excretion than placebo (p<0.05)³

¹ Micheletti MC, Zartarian M. Comparison of calcium retention measured using a radionuclide method after administration of 1 000 mg elemental calcium in two different galenic forms, in one or two doses. Rev Rhum (English Ed) 1996; 63: 51-55.

² Jiexiong W et al. The calcium absorption of two kinds of calcium carbonate plus vitamin D preparations in healthy volunteers. Chinese Pharmaceutical Journal 1998; 33: 482-484.