Mechanism of Action (MOA) of Disintegrant Excipients

Disintegration is an early way to evaluate whether a drug is effective. The disintegration time is an important control index for tablets, capsules, and dripping pills. Disintegration means that the solid preparation disintegrates and dissolves or breaks into granules under specified conditions. Except for insoluble coating materials or broken capsule shells, all solid preparations should pass through the screen. Therefore, a disintegration test should be carried out to make sure that a drug is released within a specified time.

The disintegration time of a drug is of great significance to the bioavailability of the drug. In the case of slow disintegration where the drug is discharged in its original form without disintegration, the efficacy of the drug will be reduced.

Disintegrant used in disintegration test

Disintegrants refer to excipients that promote the rapid disintegration of tablets into small particles in the gastrointestinal tract. Since the drug is compressed into a tablet by a large pressure, the porosity is small and the binding force is very strong. Even for the drug compressed into a tablet that is easily soluble in water, it takes a certain amount of time to get dissolved or disintegrated. The disintegration of the tablet is generally the first step in the dissolution of the drug. In order for tablets to quickly exert their drug effects, disintegrants are generally required to be added except for buccal tablets, sublingual tablets, implant tablets, and long-acting tablets that require slow drug release.

Mechanism of action of disintegrant

The main function of the "disintegrant" is to eliminate the binding force of the tablet formed by the binder or pressure to cause the tablet to disintegrate. The disintegration mechanism of tablets varies with the nature of the raw materials and excipients used in tablet production. Below are several disintegration mechanisms.

1. Capillary action

This type of disintegrant can maintain the pore structure of the compressed tablet in the tablet, form a capillary channel that is easy to wet and present a lower interfacial tension in an aqueous medium. When the tablet is placed in water, water can quickly enter the inside of the tablet with the capillary tube, so that the entire tablet is wetted and disintegrated. Starch and its derivatives, and cellulose derivatives all belong to this type of disintegrant.

This type of disintegrant is generally added both internally and externally. The external addition method is conducive to the rapid disintegration of the tablet into particles, while the internal addition method is conducive to the finer dispersion of the particles and can improve the hardness of the agent.

2. Swelling effect

In addition to capillary action, some disintegrants themselves can swell with water to cause the tablet to disintegrate. For example, the starch derivative sodium carboxymethyl starch can swell in cold water, and the swelling effect of its granules is very significant, causing the tablet to disintegrate rapidly.

3. Gas production

Disintegrants that produce gas are mainly used for tablets that need to disintegrate or dissolve quickly, such as effervescent tablets, foam tablets, etc. In the effervescent disintegrant, citric acid or tartaric acid plus sodium carbonate or sodium bicarbonate is commonly used. When it meets water, carbon dioxide gas is generated, and the tablet disintegrates with the help of gas expansion.

4. Enzymatic hydrolysis

Some enzymes have an effect on certain excipients in the tablet. When they are formulated in the same tablet, they can quickly disintegrate in contact with water. For example, when the starch slurry is used as a binder, amylase can be added to dry granules, and the compressed tablets formulated by this way can disintegrate quickly once in contact with water. Commonly used adhesives and their corresponding enzymes are starch and amylase, cellulose and cellulose, gum and hemicellulose, gelatin and protease, sucrose and invertase, alginates and carrageenase, etc.

The author has been engaged with pharmaceutical preparation for years and has accumulated experience in excipients and drug formulation.