PHARMACEUTICAL APPROACHES TO

COLON TARGETED DRUG DELIVERY

SYSTEM

Anirban SahaM.Pharm

(Pharmaceutics)Year- 1st , Semester- 2

Amity University.sahaanirban18@gmail.

com

AMITY INSTITUTE OF

PHARMACY

IntroductionAnatomy and Physiology of colonFactors governing Colonic drug deliveryStrategies for Targeting drug to colonTargeting Approaches to colonEvaluation of C.T.D.D.SMarketed PreparationApplicationsFuture ProspectsConclusionReferences

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-:CONTENTS:-

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.

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INTRODUCTION

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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ADVANTAGES

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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DISADVANTAGES

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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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Ascending colon

Transverse colon

Descending colon

Sigmoid colon

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Contd…

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THE PH RANGES OF GIT

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Length and internal diameter colon &

small intestine

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.

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FUNCTIONS OF COLON

Ulcerative colitis.

Inflammatory bowel disease (IBD).

Chron’s disease.

Colo-Rectal cancer.

Others as amebiasis & Diarrhoea.

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DISORDERS OF COLON

Physiological Factors :-

Small intestinal transit

Colonic transit

Gastric emptying

Stomach and intestinal pH

Colonic micro flora and enzymes

Pharmaceutical factors :-

Drug candidates

Drug carrier

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FACTORS GOVERNING COLONIC DRUG DELIVERY

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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Strategies for targeting Drug to Colon

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

Time - dependent delivery

Pressure- dependent delivery and

Bacteria—dependent delivery

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Continue…

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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TARGETING APPROACHES TO COLON

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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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1.Covalent linkage of the drug with a carrier

Glycoside conjugates:- Drug is conjugated with Glycoside.

Glucuronide conjugates:- Drug is conjugated with Glucuronide.

Cyclodextrinconjugates:- Drug is conjugated with cyclodextrin.

Dextran conjugates:- Drug is conjugated with dextrin.

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

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Similarly

Coating with polymers . Coating with pH-sensitive polymers Coating with biodegradable polymers Embedding in matrices Embedding in biodegradable matrices and hydro gels Embedding in pH-sensitive matrices Timed release systems Redox-sensitive polymers Bioadhesive systems Coating with micro particles Osmotic controlled drug delivery

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2 Approaches to deliver the intact molecule to colon

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Biodegradable poly saccharides

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EVALUATION OF COLON TARGETED DRUG DELIVERY

MARKETED PREPERATION

MARKETED PRODUCTS

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CONCLUSION

1) Chourasia M.K., Jain S.K.,Pharmaceutical approaches to colon specific drug delivery system,J Pharm PharmaceutSci,2003; 6(1):33-66

2) Madhu E.N., Panaganti S., L. Prabakaran, and Jayveera K. N., Novel Colon Specific Drug Delivery System: A Review, , IJPSR, 2011; 2(10): 2545-2561

3) Tapaswi R.D., Verma P., Matrix Tablets: An Approach towards Oral Extended, Release Drug Delivery, International Journal of Pharma Research & Review, Feb 2013; 2(2):12-24

4) Kshirsagar S.J.,Bhalekar M.R,Umap R.R. In vitro in vivo comparison of two pH Sensitive Eudragit polymers for colon specific drug delivery. J. Pharm. Sci., 2009;1(4):61-70.

5) Shendge R.S., Fatima J., Sayyad, Kishor S., Salunkhe and Bhalke` R.D.,. Development of specific delivery of aceclofenac by using effective binder system of ethyl cellulose. Int. J. Pharm. Bio. Sci., 2010;1(3):1-5.

6) Patel B.P. and Avinash S. Dhake.,Multiparticulate approach: an emerging trend in colon specific drug delivery for Chronotherapy, Journal of Applied Pharmaceutical Science, 2011, 01 (05): 59-63

7) Gang C.F., An, Mei-Juan Zou, Jin Sun, Xiu-HuaHao, Yun-Xia He, Time- and pH-dependent colon-specific drug delivery for orallyadministereddiclofenac sodium and 5-aminosalicylic acid, World J Gastroenterol World, 2004, 10(12): 1769-1774

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