These newer substances are more effective at lower concentrations with greater disintegrating efficiency and mechanical strength. On contact with water the superdisintegrants swell, hydrate, change volume or form and produce a disruptive change in the tablet. Effective superdisintegrants provide improved compressibility, compatibility and have no negative impact on the mechanical strength of formulations containing high-dose drugs.
List of Superdisintegrant
|EXAMPLE||SUPER-DISINTEGRANTS||MECHANISM OF ACTION||SPECIAL COMMENT|
Swells 4-8 folds in <10 seconds.
Swelling and wicking both.
Swelling is in two dimensions.
-Direct compression or granulation-Starch free
|Swells 7-12 folds in <30 seconds|
Swells very little and returns to original size after compression but act by capillary action
|Swells in three dimensions and high level serve as sustain release matrix|
Water insoluble and spongy in nature so get porous tablet
Sodium Starch Glycolate
|Swells 7-12 folds in <30 seconds||Swells in three dimensions and high level serve as sustain release matrix|
|Crosslinked alginic acid||Alginic acid NF|
|Rapid swelling in aqueous medium or wicking action||Promote disintegration in both dry or wet granulation|
|Natural super Disintegrants||Soy polysaccharides|
|Rapid Dissolving||Does not contain any starch or sugar. Used in nutritional products.|
|Calcium Silicate||Wicking action||Highlyporous, Optimum concentration is between 20-40%|
Modified celluloses Carboxymethylcellulose / Crosslinked cellulose and its derivative (Croscarmellose Sodium)
Cross-linked sodium carboxymethylcellulose is a white, free flowing powder with high absorption capacity. It has a high swelling capacity and thus provides rapid disintegration and drug dissolution at lower levels. It also has an outstanding water wicking capability and its cross-linked chemical structure creates an insoluble hydrophilic, highly absorbent material resulting in excellent swelling properties. Its recommended concentration is 0.5–2.0%, which can be used up to 5.0% L-HPC (Low substituted Hydroxy propyl cellulose). It is insoluble in water, swells rapidly and is used in the range of 1-5%. The grades LH- 11 and LH-21 exhibit the greatest degree of swelling.
Cross-linked polyvinylpyrrolidone / Crosslinked PVP
It is a completely water insoluble polymer. It rapidly disperses and swells in water but does not gel even after prolonged exposure. The rate of swelling is highest among all the superdisintegrants and is effective at 1-3%. It acts by wicking, swelling and possibly some deformation recovery. The polymer has a small particle size distribution that imparts a smooth mouth feel to dissolve quickly. Varieties of grades are available commercially as per their particle size in order to achieve a uniform dispersion for direct compression with the formulation.
Modified starches / Crosslinked starch
Sodium starch glycolate is the sodium salt of a carboxymethyl ether of starch. It is effective at a concentration of 2-8%. It can take up more than 20 times its weight in water and the resulting high swelling capacity combined with rapid uptake of water accounts for its high disintegration rate and efficiency. It is available in various grades i.e. Type A, B and C, which differ in pH, viscosity and sodium content. Other special grades are available which are prepared with different solvents and thus the product has a low moisture (<2%) and solvent content (<1%), thereby being useful for improving the stability of certain drugs.
Cross-linked Alginic Acid
It is insoluble in water and disintegrates by swelling or wicking action. It is a hydrophilic colloidal substance, which has high sorption capacity. It is also available as salts of sodium and potassium.
Soy polysaccharide / Natural super Disintegrants
It is a natural super disintegrant that does not contain any starch or sugar so can be used in nutritional products.
It is a highly porous, lightweight superdisintegrant, which acts by wicking action. Its optimum concentration range is 20-40%
It is an anionic polysaccharide of linear tetrasaccharides, derived from Pseudomonas elodea having good superdisintegrant property similar to the modified starch and celluloses.
Xanthan Gum derived form Xanthomonas campestris is official in USP with high hydrophilicity and low gelling tendency. It has low water solubility and extensive swelling properties for faster disintegration.
Ion exchange resins
The INDION 414 has been used as a superdisintegrant for ODT. It is chemically cross-linked polyacrylic, with a functional group of – COO – and the standard ionic form is K+. It has a high water uptake capacity.
Although there are many superdisintegrants, which show superior disintegration, the search for newer disintegrants is ongoing and researchers are experimenting with modified natural products, like formalincasein, chitin, chitosan, polymerized agar acrylamide, xylan, smecta, key-jo-clay, crosslinked carboxymethylguar and modified tapioca starch.
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