# Absorption, Scintigraphy, Efficacy and Tolerability of Short-Term Calcium Carbonate Supplementation in Healthy Subjects

## TL;DR

This study shows that short-term calcium carbonate supplementation is well-absorbed, effective for bone density, and well-tolerated in healthy individuals.

## Contribution

The study provides new empirical evidence on the absorption, efficacy, and safety of Gemcal DS tablets in healthy subjects.

## Key findings

- Gemcal DS tablets showed peak serum calcium levels at four hours post-dosing with a bioavailability of 38.2±4.8 µg/mL/hour.
- Scintigraphy confirmed complete dispersion of the tablet in the small intestine within four hours.
- Short-term use increased bone density and P1NP levels while decreasing PTH and maintaining tolerability.

## Abstract

Orally administered calcium carbonate tablets are commonly prescribed as a calcium supplement, and their short-term use is popular among the healthy population. However, being a nutritional supplement, the in vitro properties and clinical efficacy of calcium carbonate supplements are sometimes compromised. The present study aimed to assess the absorption, in vivo dispersion, efficacy and tolerance of Gemcal DS tablet following its short-term use for four weeks. Post-dosing, a gradual rise in serum calcium concentration was observed and the peak increment in serum calcium (4.13±0.38 µg/mL) was reached at four hours. The bioavailability, determined as the area under the curve for six hours (ΔAUC0-6) of serum calcium, was 38.2±4.8 µg/mL/hour.

Scintigraphy images showed that the disintegration of the study product initiated within 15 minutes in the stomach, with the radioactive trail suggesting complete dispersion within four hours in the small intestine. No intact tablet was observed in the small intestine or the large intestine. An increase in mean serum calcium (~3%) and procollagen type 1 N-terminal propeptide (P1NP) (~13.2%) was observed post-treatment.

In contrast, a decrease in parathyroid hormone (PTH) levels was noted. Dual-energy X-ray absorptiometry (DEXA) scan results revealed an increase in bone density from 1.1968±0.05 (baseline) to 1.2115±0.06 g/cm2, post-treatment. T-scores were also improved in all the subjects, except 1 subject whose T-score remained the same. The Gastrointestinal Symptom Rating (GSR) score at the end of the study (0.42±0.62) was not significantly different (p>0.05) from the baseline GSR score (0.33±0.54), indicating that the treatment was safe and tolerable. In conclusion, Gemcal DS tablets produced an appropriate pharmacokinetic and pharmacodynamic response and could be recommended for short-term use in the healthy population.