Analysis of Dissolution, Pharmacokinetic, and Bone-Protective Differences Among Calcium Formulations with Different Dosage Forms and Calcium Sources

Background: Calcium formulations are important nutritional interventions for improving insufficient calcium intake and assisting in the prevention and treatment of osteoporosis. In vitro and in vivo performance may be influenced by dosage form, calcium source, and formulation composition. In this study, an integrated approach combining in vitro dissolution, pharmacokinetic, and pharmacodynamic evaluations was used to compare the comprehensive performance of nine calcium formulations and related functional components. Methods: The nine samples were coded as CS-1 to CS-9 according to a predefined order. Calcium release characteristics were determined under simulated gastrointestinal pH conditions using a flow-through cell system. Calcium concentrations in rat plasma, feces, and urine were measured by inductively coupled plasma optical emission spectrometry (ICP-OES) to evaluate calcium exposure, excretion, and retention. Meanwhile, the bone-protective effects of different calcium preparations were assessed in a retinoic acid-induced osteoporotic ICR mouse model, and the pharmacodynamic performance of calcium citrate and various bone-derived peptide preparations was investigated in a calcium-deficient female Sprague–Dawley (SD) rat model. Results: CS-1 exhibited rapid and nearly complete calcium release in simulated gastric fluid and showed a relatively favorable dissolution profile under sequential gastrointestinal pH conditions. Calcium balance analysis indicated that calcium retention in rats was relatively higher after administration of CS-1. Animal experiments showed that different calcium sources and bone-derived peptide preparations improved bone-related parameters to varying degrees, among which CS-1 produced relatively consistent improvements in bone microarchitecture and biomechanical properties. As a functional component of the CS-1 formulation, salmon bone-derived ingredients showed activity in the comparative pharmacodynamic evaluation, suggesting that they may contribute to the overall bone-protective effect. Conclusions: Different calcium formulations showed distinct profiles in dissolution behavior, calcium retention, and bone-protective effects. Among the tested samples, CS-1 demonstrated relatively favorable overall performance, which may be related to its liquid dosage form and salmon bone-derived functional components.