AA

PRESENTATIONPRESENTATION

ONON

PHARMACEUTICAL APPROACHES TO COLON

TARGETED DRUG DELIVERY SYSTEM

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Presented by: RAJ KISHORPresented by: RAJ KISHOR Tech Observer India Pvt. Tech Observer India Pvt.

LtdLtd

The Global CROThe Global CRO

Email ID-raryan859@gmail.com

-:CONTENTS:-

Introduction 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 Marketed Preparation Applications Future Prospects Conclusion References

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INTRODUCTION

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.3

ADVENTAGES

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

infections)

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.

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Disadvantages

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.

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Location-in abdominal cavity

Made up of-

Serosa – areolar tissue. Muscularis externa – muscular

coat. Submucosa – connective tissue. Mucosa – epithelium.

ANATOMY AND PHYSIOLOGY OF COLON

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Contd…

Ascending colon

Transverse colon

Descending colon

Sigmoid colon

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THE PH RANGES OF GIT

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Length and internal diameter colon & small intestine

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FUNCTION OF COLON

Provides suitable environment for the growth of colonic

microorganisms,

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

time.11

DISORDERS OF COLON

Ulcerative colitis.

Inflammatory bowel disease (IBD).

Chron’s disease.

Colo-Rectal cancer.

Others as amebiasis & Diarrhoea.

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Continue…

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FACTORS GOVERNING COLONIC DRUG DELIVERY

Physiological Factors:-

Small intestinal transit

Colonic transit

Gastric emptying

Stomach and intestinal pH

Colonic micro flora and enzymes

Pharmaceutical factors….(a)Drug candidates

(b)Drug carrier

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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 targeting .

These strategies are either drug specific ( prodrug ) or formulation –specific (coated or matrix preparation).

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Continue…

The most commonly used targeting mechanisms are:- pH – dependent delivery

Time - dependent delivery

Pressure- dependent delivery and

Bacteria—dependent delivery

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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 colonic bacteria.

(5) bioadhesive systems and osmotic controlled drug delivery systems

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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.

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.1Azo bond conjugates-Drug is conjugated via azo bo

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Similarly

1.2. Glycoside conjugates:- Drug is conjugated with Glycoside.

1.3. Glucuronide conjugates:-Drug is conjugated with Glucuronide.

1.4.Cyclodextrinconjugates:-Drug is conjugated with cyclodextrin.

1.5. Dextran conjugates:-Drug is conjugated with dextrin.

1.6. Amino-acid conjugates:-Drug is conjugated with amino acid.

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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

hydro gels 2.2.2. Embedding in pH-sensitive matrices 2.3. Timed release systems 2.4Redox-sensitive polymers 2.5. Bioadhesive systems 2.6. Coating with micro particles 2.7. Osmotic controlled drug delivery

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Biodegradable poly saccharides

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Osmotically controlled colon targeted drug delivery

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Target the drug locally to the colon

Single or 5-6 push-pull units

Contains an osmotic push layer and a drug layer

Surrounded by a semi permeable membrane

Orifice is drilled through the membrane next to the drug layer

EVALUATION OF COLON TARGETED DRUG DELIVERY

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MARKETED PREPERATION

MARKETED PRODUCT

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CONCLUSION

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