The Primary Function of Sodium Starch: A Superdisintegrant Explained

December 21, 2025 •

4 min read

Sodium starch glycolate (SSG) was the first superdisintegrant introduced to the pharmaceutical industry, significantly outperforming traditional disintegrants. The primary function of sodium starch is to cause the rapid disintegration of tablets and capsules upon contact with water, ensuring efficient drug release.

Quick Summary

Sodium starch glycolate functions as a superdisintegrant in pharmaceuticals, rapidly absorbing water to swell and break apart tablets and capsules, which facilitates quick drug release and enhances bioavailability.

Key Points

Superdisintegrant: The primary function of sodium starch glycolate (SSG) in pharmaceuticals is to rapidly break down tablets and capsules, ensuring efficient drug release.
Rapid Swelling: SSG achieves disintegration by quickly absorbing water and swelling significantly, generating the internal pressure needed to fracture the tablet matrix.
Enhanced Bioavailability: This rapid disintegration leads to faster dissolution of the active ingredient, which improves its absorption and overall bioavailability.
Versatile Functions: Besides its disintegrant role, SSG can also act as a suspending agent, gelling agent, and can be tailored for controlled-release systems.
Broad Applications: SSG is widely used beyond pharmaceuticals, with applications in the food industry as a thickener and stabilizer, and in cosmetics for texture enhancement.
Manufacturing Impact: The performance of SSG can be affected by factors like particle size, cross-linking, and pH, which are considered during formulation development.
Source Variation: The starch source, such as potato or corn, and different manufacturing processes can result in varying grades of SSG with distinct functional properties.

The Core Function: A Superdisintegrant in Pharmaceuticals

At its core, the function of sodium starch is that of a powerful superdisintegrant, a class of excipient used primarily in pharmaceutical solid dosage forms like tablets and capsules. As a modified starch derivative, chemically known as the sodium salt of carboxymethyl ether starch, its key purpose is to promote the fast and efficient breakup of a tablet matrix after ingestion. This process is critical for ensuring that the active pharmaceutical ingredient (API) is released quickly and effectively into the body for absorption, directly impacting a drug's efficacy and bioavailability.

The Mechanism of Disintegration

Sodium starch glycolate (SSG) achieves its potent disintegrating effect through a process of rapid water absorption and swelling. Upon coming into contact with the aqueous fluids of the gastrointestinal tract, the SSG particles within the tablet matrix act like tiny, powerful sponges.

Water Absorption: Due to its porous, cross-linked structure, SSG rapidly absorbs water, drawing it into the tablet's core.
Volumetric Swelling: As the water is absorbed, the SSG particles swell significantly in volume, forming a gel-like substance.
Pressure Generation: The immense pressure exerted by this swelling from within the tablet matrix overcomes the tablet's binding forces.
Tablet Fracture: This internal pressure causes the tablet to break apart into smaller granules or fragments, increasing the surface area for dissolution.
Enhanced Dissolution: The faster dissolution of the API from the smaller particles leads to more rapid absorption and a quicker therapeutic effect.

Versatile Applications Beyond Disintegration

While its role as a superdisintegrant is paramount, sodium starch glycolate's functions extend to other areas, showcasing its versatility as a pharmaceutical excipient and its utility in other industries.

Other Pharmaceutical Functions

Suspending Agent: In liquid formulations, SSG can act as a suspending agent to prevent solid particles from settling at the bottom, ensuring uniform distribution.
Gelling Agent: By absorbing large volumes of water, SSG can be used to form gels, a property utilized in various formulations.
Controlled Release: By modifying the particle size and the degree of cross-linking, formulators can leverage SSG's properties to achieve controlled or sustained drug release profiles, particularly in matrix-based systems.

Functions in Other Industries

Food Industry: SSG is used as a stabilizer and thickening agent in various food products, such as instant foods, sauces, and soups. It can also function as an anti-aging agent in bread and an additive in ice creams.
Cosmetics: In cosmetic formulations like creams and lotions, SSG acts as a stabilizer and thickener, contributing to the desired texture and consistency.
Textile Industry: It can be used as a fixative in dyeing processes to improve color retention and as an ingredient in fabric softeners.
Paper Industry: SSG enhances the gloss and smoothness of paper products when used in coatings, improving print quality.

Comparison of Sodium Starch Glycolate to Other Disintegrants


Feature	Sodium Starch Glycolate (SSG)	Croscarmellose Sodium (CCS)	Crospovidone (CP)
Mechanism	Rapid water absorption and swelling to cause mechanical pressure and burst tablets.	Wicking and swelling to create a channel-like structure for fluid penetration.	Capillary action and rapid swelling to disrupt the tablet structure.
Swelling Action	High swelling capacity, forming a gel matrix upon hydration.	Rapid swelling, with a progressive and quick disintegration profile.	Rapid water uptake and swelling, excellent for fast-acting formulations.
Applications	Immediate-release tablets, orally disintegrating tablets (ODTs), capsules, and some controlled-release systems.	Immediate-release tablets, particularly effective with poorly soluble drugs.	Excellent for direct compression formulations and chewable tablets.
Compatibility	Compatible with a wide range of APIs and manufacturing processes, but performance can be affected by the process.	Compatible with most APIs; wettability enhancement is an advantage for certain drugs.	Inert and compatible with many APIs, very stable under various conditions.

Key Factors Influencing SSG Performance

The efficacy of SSG is not uniform across all formulations and can be influenced by several factors:

Particle Size: Smaller SSG particles can form a thick gel layer that hinders water penetration, potentially delaying disintegration. Larger particles are often more efficient.
Cross-linking: The degree of cross-linking affects SSG's swelling power and strength. Higher cross-linking makes the starch grains stronger and less susceptible to damage during wet granulation, while also reducing swelling.
Formulation pH: Some grades of SSG are designed for specific pH environments. A low pH grade (Type B) may be used for acidic drug formulations.
Salt Content: High levels of sodium chloride, a reaction by-product in SSG synthesis, can reduce the swelling rate by competing for water absorption.

Conclusion

The primary function of sodium starch glycolate is its role as a highly efficient superdisintegrant, driving the rapid breakdown of solid dosage forms to enable quick drug release. Its remarkable ability to absorb water and swell makes it an indispensable component for enhancing the dissolution and bioavailability of active ingredients. While its main application is in pharmaceuticals, SSG's versatility as a suspending, gelling, and thickening agent has expanded its utility into the food, cosmetics, and textile industries, cementing its status as a vital modified starch in modern manufacturing. The careful selection of SSG grade based on formulation needs and manufacturing processes is key to optimizing its performance and ensuring the effectiveness of the final product.

For more detailed information on excipients and their functions, consult authoritative sources such as pharmacopoeias and material databases.

Frequently Asked Questions

The main role of sodium starch, specifically sodium starch glycolate (SSG), is to act as a superdisintegrant. It helps a tablet break apart rapidly when it encounters water in the body, which is essential for the quick release of the active ingredients.

SSG works by rapidly absorbing water due to its porous structure. This absorption causes the SSG particles to swell significantly, generating internal pressure that forces the tablet matrix to rupture and break apart into smaller particles.

Yes, SSG is widely used in oral pharmaceutical formulations and is generally regarded as a nontoxic and nonirritant material. It is approved for use as an excipient by regulatory bodies like the FDA, though ingestion of very large quantities is not recommended.

Yes, beyond its use in pharmaceuticals, SSG is utilized in the food industry as a thickening agent, stabilizer, and anti-aging agent. It is also found in cosmetics, personal care products, and even agricultural applications.

Several factors can influence SSG's performance, including particle size, the degree of cross-linking, and the pH of the surrounding environment. For example, excessive cross-linking can reduce swelling, while smaller particle sizes can sometimes hinder water penetration.

Sodium starch glycolate is a chemically modified starch. It is cross-linked and carboxymethylated to enhance its hydrophilicity and reduce its solubility, giving it superior water absorption and swelling properties compared to native starch.

SSG is available under various brand names, with some common examples in the pharmaceutical industry including Explotab, Primojel, and Vivastar.

While both are superdisintegrants, SSG works primarily by rapid, forceful swelling, whereas CCS acts through both swelling and wicking fluid into the tablet matrix. SSG's swelling can be more immediate and forceful.