For pharmaceutical scientists and procurement specialists, selecting the right excipients is a foundational step in developing successful drug products. Cellulose Acetate Phthalate (CAP), with its CAS number 9004-38-0, is a polymer widely utilized for its unique pH-dependent solubility, making it ideal for enteric coatings and controlled-release formulations. When you plan to buy CAP, understanding its critical specifications is paramount to ensuring product efficacy and regulatory compliance. This guide highlights the key parameters that R&D scientists and procurement managers should focus on when evaluating CAP from manufacturers.

The primary function of CAP in pharmaceuticals is to act as a barrier in acidic environments, typically the stomach, and dissolve in the more alkaline conditions of the small intestine. This characteristic is governed by specific chemical and physical properties of the CAP polymer. Here are the essential specifications to consider:

  • Appearance: CAP is typically supplied as a white to off-white powder or granular material. Consistent appearance across batches is a good initial indicator of quality.
  • Purity and Pharmacopoeial Compliance: For pharmaceutical applications, CAP must meet the standards set by relevant pharmacopoeias (e.g., USP, EP, JP). This ensures the absence of harmful impurities and guarantees predictable performance. Always request a Certificate of Analysis (CoA) confirming compliance.
  • pH-dependent Solubility: This is the most critical functional specification. CAP should be insoluble in acidic solutions (pH 1-5) and soluble in neutral to alkaline solutions (pH 5.5-7.0). Manufacturers should provide data or specifications detailing this behavior.
  • Acid Value/Phthalate Content: This specification relates to the degree of phthalate esterification, which directly influences the dissolution pH. It’s a key parameter for formulators to ensure the coating performs as intended.
  • Acetyl Content and Degree of Substitution: These values indicate the extent of acetylation and phthalylation on the cellulose backbone, influencing the polymer's physical properties like glass transition temperature and mechanical strength of the film.
  • Viscosity: The solution viscosity of CAP is important for determining its processability in coating applications, affecting sprayability and film formation.
  • Moisture Content: CAP is hygroscopic, so controlling its moisture content is important for storage stability and processing consistency.

When engaging with potential suppliers, especially those based in China, it is crucial to request detailed product specifications and engage in open communication. Understanding these critical parameters will empower you to make informed decisions when you need to buy Cellulose Acetate Phthalate, ensuring you select a material that will contribute effectively to the success of your pharmaceutical formulations.

By meticulously reviewing these specifications and partnering with a reliable CAP manufacturer, pharmaceutical companies can confidently integrate this versatile excipient into their product development pipeline, ensuring both quality and therapeutic effectiveness.