Determination of the binding parameter constants of Renagel capsules and tablets utilizing the Langmuir approximation at various pH by ion chromatography

Sevelamer hydrochloride is a cross-linked polymeric amine; it is the active ingredient in Renagel capsules and tablets. Sevelamer hydrochloride is indicated for the control of hyperphosphatemia in patients with end-stage renal disease. The binding parameter constants of sevelamer hydrochloride were determined using the Langmuir approximation for three different dosage forms at pH 4.0, 5.5 and 7.0. The three dosage forms were Renagel 403 mg capsules, Renagel 400 mg tablets and Renagel 800 mg tablets. The results demonstrate the equivalency of all three dosage forms at each pH. The results also demonstrate a shift in the binding mechanism from pH 4.0 to 7.0.