Transient acid exposure increases sevelamer HCl phosphate binding.

Area of Science:

• Nephrology
• Pharmacology
• Materials Science

Background:

• Sevelamer hydrochloride (HCl) is a phosphate binder used to manage hyperphosphatemia.
• Patient variability in sevelamer HCl dosing suggests potential drug-environment interactions.
• The stomach's acidic environment may influence sevelamer's phosphate binding capacity in the intestine.

Purpose of the Study:

• To investigate if transient exposure to acidic conditions alters sevelamer HCl's phosphate binding ability.
• To determine if acid exposure increases reactive sites or enhances polymer swelling.

Main Methods:

• Sevelamer HCl tablets were incubated at pH 1, 2.3, and 7 for 1 hour.
• Phosphate uptake was measured after 3 hours incubation at pH 7.
• Particle swelling was assessed using computerized image analysis in real-time.

Main Results:

• Phosphate uptake was significantly higher (p = 0.0006) after pre-exposure to pH 1 (3.13 mequiv./g) compared to pH 7 (1.85 mequiv./g).
• No significant difference in particle swelling was observed between pH 1 and pH 7 pre-exposure (p > 0.8).
• Findings indicate increased protonation, not swelling, enhances phosphate binding.

Conclusions:

• Transient exposure to acidic environments enhances sevelamer HCl's phosphate binding capacity.
• This effect is attributed to an increase in protonated amine groups, enhancing reactivity.
• Patients with achlorhydria may not experience this beneficial interaction with sevelamer HCl.