Abstract
Purpose: The phosphate binding capacity of PA21, a novel phosphate binder, was compared with
those of other phosphate binders in vitro and in vivo.
Methods: 1) For in vitro studies, PA21, sevelamer hydrochloride, lanthanum carbonate hydrate,
calcium carbonate, and ferric citrate hydrate were incubated with a phosphate solution
at 37°C for 2 h. Phosphate binding capacity was assessed at simulated gastrointestinal
tract pH levels of 2, 5, and 8 for estimation of clinical effects, and the quantity
of phosphate adsorbed by each phosphate binder was determined. 2) For in vivo studies,
rats were orally administered various phosphate binders after the oral administration
of phosphate solution (100 mg/kg) adjusted to pH 2, 5, or 8, and the effects of PA21
and other phosphate binders on the serum phosphorus level of the rats were investigated.
Results: 1) The in vitro studies revealed that PA21 and sevelamer hydrochloride adsorbed phosphate
better at all tested pH levels than lanthanum carbonate hydrate, calcium carbonate,
and ferric citrate hydrate, and PA21 showed the most potent phosphate binding capacity
among the tested compounds. 2) The in vivo studies showed that PA21 dose-dependently
inhibited the increase in the serum phosphorus level after the administration of phosphate
solution and no difference in the extent of inhibition by PA21 was observed at the
different pH levels (in contrast to other phosphate binders).
Conclusion: These results indicated that PA21 has a phosphate binding capacity over the entire
pH range of the GI tract.
Key words
sucroferric oxyhydroxide - lanthanum carbonate hydrate - sevelamer hydrochloride -
calcium carbonate - ferric citrate hydrate
