''Pharmaceutical Approaches to colon Targeted Drug Delivery system'', Presented By: Raj Kishor [CRC] , Tech Observer iNDIA Pvt. Ltd ...The Global CRO
PHARMACEUTICAL APPROACHES TO COLON
TARGETED DRUG DELIVERY SYSTEM
Presented by: RAJ KISHOR
Tech Observer India Pvt.
The Global CRO
Anatomy and Physiology of colon
Factors governing Colonic drug delivery
Strategies for Targeting drug to colon
Targeting Approaches to colon
Evaluation of C.T.D.D.S
Oral route is considered to be most convenient for administration of
drug to patient.
Colon is used as site of Targeted drug delivery.
Colon was considered as a BLACK-BOX , as most of the drug are
absorbed from the upper part of the GI tract.
Prime objective-Beneficial in the treatment of colon diseases.
Increase the pharmacological activity.
Reduce dosing & side effects.
Prevent drug from degradation.
The site specific delivery of drug to lower part of GIT,
for localized treatment of several colonic diseases.
(ulcerative colitis, Chron's disease, carcinomas and
Prevent drug from degradation
Ensure direct treatment at disease site.
Suitable absorption site for Protein & Peptide drug.
Used to prolong the drug therapy.
Improved drug utilization.
Substantial variation in gastric retention time may
affect drug delivery.
Diseased condition may affect the colonic transit time
and drug release profile.
pH level of colon may vary between individuals due to
disease, state and temperature of food consumed.
ANATOMY AND PHYSIOLOGY OF COLON
Location-in abdominal cavity
Made up of Serosa – areolar tissue.
Muscularis externa – muscular
Submucosa – connective tissue.
Mucosa – epithelium.
Length and internal diameter colon & small intestine
FUNCTION OF COLON
Provides suitable environment for the growth of colonic
Absorption of water and Na+ from the lumen,
concentrating the fecal content, Secretion of K+ ions,
Storage reservoir of faecal contents,
Expulsion of the contents of the colon at an appropriate
Strategies for targeting Drug to colon
An oral colonic delivery system should retard drug release
in the stomach and small intestine but allow complete
release in the colon.
A variety of strategies has been used and systems have
been developed for the purpose of achieving colonic
These strategies are either drug specific ( prodrug ) or
formulation –specific (coated or matrix preparation).
The most commonly used targeting mechanisms
are: pH – dependent delivery
Time - dependent delivery
Pressure- dependent delivery and
TARGETING APPROACHES TO COLON
The various targeting Approaches of orally administered
drugs to the colon include:(1)Covalent linkage of a drug with a carrier.
(2)Coating with pH-sensitive polymers.
(3)Formulation of timed released systems.
(4) Exploitation of carriers that are degraded specifically by
(5) bioadhesive systems and osmotic controlled drug
1.Covalent linkage of the drug with a carrier
It involves the formation of a covalent linkage between
drug and carrier in such a manner that upon oral
administration the moiety remains intact in the stomach
and small intestine.
This approach chiefly involves the formation of prodrug,
which is a pharmacologically inactive derivative of a
parent drug molecule that requires spontaneous or
enzymatic transformation in the biological environment to
release the active drug.
1Azo bond conjugates-Drug is conjugated via azo bo
1.2. Glycoside conjugates:- Drug is
conjugated with Glycoside.
1.3. Glucuronide conjugates:-Drug is
conjugated with Glucuronide.
conjugated with cyclodextrin.
1.5. Dextran conjugates:-Drug is conjugated
1.6. Amino-acid conjugates:-Drug is
conjugated with amino acid.
2 Approaches to deliver the intact molecule to colon
2.1.Coating with polymers .
2.1.1. Coating with pH-sensitive polymers
2.1.2. Coating with biodegradable polymers
2.2 Embedding in matrices
2.2.1. Embedding in biodegradable matrices and
2.2.2. Embedding in pH-sensitive matrices
2.3. Timed release systems
2.5. Bioadhesive systems
2.6. Coating with micro particles
2.7. Osmotic controlled drug delivery
Osmotically controlled colon targeted drug delivery
Target the drug locally to
Single or 5-6 push-pull
Contains an osmotic push
layer and a drug layer
Surrounded by a semi
Orifice is drilled through
the membrane next to the