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Mechanisms of action
1. Swelling: Disintegrant swells upon water contact, rupturing the tablet.
2. Capillary action: The disintegrant increases tablet porosity, enhancing water
penetration.
o Capillary and swelling actions may occur together.
3. Gas production: Occurs only in effervescent tablets containing citric acid and sodium
bicarbonate.

Examples of Disintegrants
1. Starch (10–20%)
o Acts by swelling and capillary action.
o Potato and corn starch are widely used, inexpensive, and effective.
o Note: Below 10%, starch acts as a glidant, not as a disintegrant.
2. Superdisintegrants (2–4%)
o Sodium starch glycolate (Explotab): Swelling action; cross-linked starch that
swells 10× in seconds.
o Crosscarmellose sodium: Swelling action; cross-linked carboxymethyl
cellulose.
o Crospovidone: Capillary action; cross-linked povidone.
3. Cellulose derivatives (by capillary action):
o Microcrystalline cellulose (Avicel)
o Carboxymethyl cellulose
4. Clays (10%)
o Bentonite
o Veegum
o Iolite (cordierite): gray mineral made of silicate of magnesium, aluminum, and
iron.
▪ Note: Loses disintegrant property during wet granulation, so it must be
used dry.

Method of Addition
• Intragranular disintegrant: Added before granulation.
• Extragranular disintegrant: Added after granulation.

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