L-su Sugar Calcium Human Pharmacokinetic Studies And Bi-stable Nuclide Tracer Technique Is The Determination Of True Calcium Absorption Rate

Calcium L-threonate is a novel drug with L-threonic acid as its calcium carrier, and it has been developed for the treatment of osteoporosis and calcium supplyment. L-threonic acid is one of the degradation products of vitamin C, and it was found in the pre-clinical studies and references that L-threonic acid could improve the proliferation of osteoblasts and formation of mineralized nodules. So the whole pharmacological activity of calcium L-threonate on osteoporosis was thought to be the cooperation of L-threonate and calcium. Since both L-threonate and calcium logically effect on osteoporosis, we should not only evaluate the absorption of calcium, but also investigate the in vivo changes of L-threonate, so as to accelerate the further research of this domestic novel drug whose applications are osteoporosis and calcium supplyment.In this dissertation, an advanced HPLC-MS/MS method was established to determine L-threonate in human plasma and urine. Systemic pharmacokinetic studies of calcium L-threonate in Chinese healthy subjects were accomplished for the first time. In vivo accumulation of L-threonate was investigated and the influence from food on the absorption of L-threonate was also studied in the research.Moreover, a double-label stable-isotope technique was used to measure the true fractional calcium absorption of calcium L-threonate for the first time. Importance of this technique in calcium absorption and metabolism, as well as calcium bioavailability study was also discussed in this dissertation.At last, ICP-MS was used to detect microelements in human urine before and after administration, and possible interference from calcium L-threonate on metabolic balance of microelements was studied, and the relationship between doses and effect was also investigated.1. HPLC-MS/MS method to determine L-threonate in human plasma and urineAn HPLC-MS/MS method to determine L-threonate in human plasma and urine was firstly established in this study. Because many kinds of vegetables and fruits are full of vitamin C, and people inevitably take Vc in their daily lives, L-threonate as a degradation product of vitamin C seems to be an endogenous substance existing in human plasma and urine. In order to eliminate the endogenous interference, considering the primary components of plasma and urine, blank plasma and urine were respectively replaced by human albumin in 0.9% NaCl solution and 0.9% NaCl solution, and these substituted matrixes were utilized to prepare calibration curves and QC samples. Plasma and urine samples were prepared using protein-precipitation by methanol or dilution with water, after separated on a C₁₈ HPLC column, L-threonate in samples was detected by HPLC-MS/MS with MRM mode. This method proved to be effective, fast, as well as specific, and a large number of biological samples had been analyzed in a very short time, so work efficiency of PK study was greatly...