Studies On Preparation And Identification Of Lanthanum Carbonate And Alkaline Lanthanum Carbonate

The end-stage renal failure is a widespread public health problem around the world. The patient'skidneys can not excrete the body's phosphate properly. Consequently, the patients often suffer fromhyperphosphatemia (phosphate levels in blood is increased). Hyperphosphatemia may lead to a series ofproblems such as hyperthyroidism, renal osteodystrophy, etc.. In addition, hyperphosphatemia is closelyrelated to many serious cardiovascular complications. Diet control and dialysis is difficult to reduce thephosphate levels back to normal range. Thus, patients usually have to use oral phosphate binders.Hyperphosphatemia was used to be treated by using aluminium-based and calcium-basedphosphate-binding agents. However, the aluminium-based and calcium-based phosphate-binding agentsresult in aluminum toxicity and hypercalcemia if they are used in a long period.Lanthanum carbonate is a new phosphate binder with high-efficiency and insignificant sideeffect. Lanthanum carbonate as a phosphate binder for the treatment of hyperphosphatemia in end stagerenal failure patients has received FDA approval in the United States, and came into the market in January2006. Lanthanum carbonate combine with dietary phosphate in the stomach and intestines, and formlanthanum phosphate complexes which more difficult to dissolve. This complex can not pass through theintestinal wall into the body's blood and ultimately only be discharged, thereby can reduce the phosphatecontent in the blood.We propose a new method to prepare La₂(CO₃)₃·8a₂O via a reaction between NaHCO₃andLaCl₃in aqueous solution. To reduce the risk of producing La(OH)CO₃, the reaction is carried at low pHenvironments. To achieve this, the nucleation of La₂(CO₃)₃·8a₂O was promoted so that acid-baseneutralization reaction and precipitation reaction occur simultaneously and the reaction can be performed atlower pH environment. The obtained La₂(CO₃)₃·8a₂O was characterized by FT-IR, XRD, elementalanalysis, complexometric titration. Based on the investigation, we proposed an FT-IR spectroscopiccriterion and the sample of C/La to judge whether La(OH)CO₃co-exists with La₂(CO₃)₃·8a₂O or not.We also investigated the binding ability of lanthanum carbonate on the phosphorus atom. Weprepare La₂(CO₃)₃nanosheet with different crystalline water and investigate the influence of different pH values and different number of crystal water on the phosphorus-binding ability of lanthanumcarbonate.Finally we find out the number of water of crystallization of lanthanum carbonate withhigh-efficiency phosphorus binding capacity.