Polysaccharides for Colon Targeted Drug Delivery

Figures & data

Strategies for colon targeted drug delivery

Approach	Basic features
Formation of prodrugs	Covalent linkage is formed between drug and carrier, which upon oral administration reaches colon without being absorbed from upper part of GIT; in the colon drug release is triggered by high activity of certain enzymes in comparison to stomach and small intestine.
Coating with pH-sensitive polymers	Formulation is coated with enteric polymers whose integrity depends on pH and releases drug when pH moves toward alkaline range.
Coating with biodegradable polymers	Drug protected with polymer is liberated due to degradative effect of colonic bacteria
Designing formulations using polysaccharides	Dosage forms enjoy the shielding effect of polysaccharide in upper part of GIT and drug is released in the colon by swelling and biodegradable action of polysaccharidases
Timed released systems	It is based on the concept of preventing the release of drug 3–5 hr after entering into small intestine
Pressure-controlled drug delivery systems	This approach relies on the strong peristaltic waves in the colon that lead to a temporarily increased luminal pressure
Osmotic systems	The unit reaches intact to the colon where drug release takes place due to osmotic pressure generated by the entry of the solvent.

1 Chemical structure of pectin.

2 Chemical structure of amylose.

3 Chemical structure of chondroitin sulphate.

4 Chemical structure of inulin.

5 Chemical structure of guar gum.

6 Crosslinking reaction of guar gum with STMP (A) and glutaraldehyde (B and C).

7 Chemical structure of dextran.

8 Chemical structure of chitosan.

9 Chemical structure of cyclodextrins.

10 Chemical structure of alginates.