Sodium carboxymethyl starch (CMS-Na) is used in the pharmaceutical industry for several key purposes, particularly in solid dosage forms like tablets. Here are its main applications in drug formulations:

1. Disintegrant: CMS-Na is widely used as a disintegrant in tablet formulations. It helps the tablet break apart after ingestion, ensuring the drug is released efficiently and absorbed by the body. It facilitates rapid disintegration by swelling in the presence of water, enhancing the dissolution process of the active pharmaceutical ingredient (API).

2. Binder: In some formulations, CMS-Na acts as a binder, helping to hold the ingredients of a tablet together. This ensures the mechanical stability of the tablet during manufacturing, transportation, and storage.

3. Controlled Release: CMS-Na can be used in controlled-release formulations to regulate the release of the drug over time. By modifying the degree of substitution in CMS-Na, it can influence the rate at which water penetrates the tablet, affecting how quickly the drug is released.

4. Suspending Agent: In liquid formulations, CMS-Na can serve as a suspending agent, helping to keep particles of active ingredients evenly distributed throughout the liquid. This ensures consistent dosing and prevents sedimentation.

5. Thickener: It is sometimes used as a thickener in topical formulations such as creams, ointments, and gels, helping to provide a smooth texture and improve the stability of the formulation.

CMS-Na is considered safe for pharmaceutical use, being non-toxic and compatible with a wide range of active pharmaceutical ingredients. Its versatility in different drug delivery systems makes it a valuable excipient in the formulation of many types of drugs.