Calcium polystyrene sulfonate

Calcium polystyrene sulfonate (CAS 37286-92-3), commonly abbreviated as CPS, is a cation-exchange resin used in pharmaceutical manufacturing and clinical formulation. It functions by exchanging calcium ions for potassium ions in the gastrointestinal tract. This mechanism makes it the active basis for oral and rectal hyperkalemia treatments. CPS is the active pharmaceutical ingredient in finished-dose products designed to reduce elevated potassium levels in patients with renal impairment.

It is formulated into oral suspensions, powders for reconstitution, and rectal enema preparations for hospital and outpatient use. Contract manufacturers and pharmaceutical formulators source CPS as a bulk API for both branded and generic drug products. Specialty compounding pharmacies also procure CPS to prepare patient-specific dosage forms where commercial products are unavailable or unsuitable. Calcium polystyrene sulfonate is supplied as a fine, cream to buff-colored powder in bulk quantities.

The material is suited to pharmaceutical manufacturing scale and is available in pharmaceutical-grade specifications. Material is typically characterized by defined exchange capacity, particle size distribution, and moisture content to meet API requirements. Suppliers commonly provide documentation supporting GMP-compliant sourcing for industrial buyers. This includes certificates of analysis and pharmacopoeial alignment with international standards such as USP, BP, or EP guidelines.