Indications
Lanthanum carbonate is prescribed for the management of elevated serum phosphate levels in patients with end-stage renal disease (ESRD). It is specifically used to decrease serum phosphate concentrations and assist in controlling hyperphosphatemia.
Pharmacodynamics
Lanthanum carbonate functions by binding phosphate within the body. In vitro studies have demonstrated that lanthanum effectively binds phosphate over a pH range of 3 to 7, which is the range relevant to physiological conditions. At a pH of 3 to 5, lanthanum binds approximately 97% of available phosphate, while at pH 7, it binds about 67% when lanthanum is present in a two-fold molar excess compared to phosphate. Importantly, bile acids do not impact lanthanum's phosphate-binding affinity. To ensure its efficacy in binding dietary phosphate, it is necessary to administer lanthanum carbonate with meals or immediately after eating. Lanthanum carbonate has been shown to be more effective than sevelamer, another commonly used phosphate binder, in reducing serum phosphate levels and controlling hyperphosphatemia.
Absorption
The oral bioavailability of lanthanum carbonate is minimal, with absorption rates being less than 0.002%. The peak serum concentration (Cmax) is around 1.0 ng/mL, with an average serum concentration of 0.6 ng/mL. The timing of lanthanum carbonate administration, whether during meals or 30 minutes post-meal, does not significantly alter its systemic absorption.
Metabolism
Lanthanum carbonate is not subject to metabolic processes within the body and is excreted unchanged.
Mechanism of Action
Lanthanum carbonate functions as an effective phosphate binder by forming insoluble complexes with phosphate in the gastrointestinal tract, thereby preventing its absorption. This mechanism results in a reduction of both serum phosphate levels and calcium phosphate product, as dietary phosphate absorption is significantly decreased.
