Colon-specific drug delivery systems (CDDS) aim to release drugs in the colon to treat diseases localized in the region. The colon offers advantages for drug absorption and many approaches have been developed. CDDS rely on the colon's distinct pH, transit time, microflora and enzymes to trigger drug release. They include pH-sensitive coatings, prodrugs, polysaccharide matrices and time-delayed systems. In vitro and in vivo tests evaluate release profiles under gastrointestinal conditions while imaging techniques track systems in the colon. CDDS provide localized treatment with fewer side effects compared to traditional therapies.

1. Colon – Specific Drug Delivery System

2. CONTENTS
•Introduction
•Anatomy & Physiology of Colon
•Factors governing the colon drug delivery
•Colon absorption
•The major functions
•Advantages
•Pharmaceutical Approaches for Targeting Drugs to Colon
•Platform Technologies for CTDDS
•Evaluation
•Conclusion

3. Introduction:
 Colon as a site for drug delivery.
 Colon was considered as BLACK-BOX as most of the
drugs are absorbed from upper part of the GI tract.
The site specific delivery of drugs to lower parts of the GIT
is advantage for localized treatment of several colonic
diseases(IDB).
The CDDS drug release and absorption should not occur in
the stomach as well as small intestine, but only released and
absorbed once the system reaches to the colon.

4. Why is CDDS needed?
 Ensure direct treatment at the disease site.
 Lower dosing and less side effects.
 Beneficial in the treatment of colon diseases.
 Suitable absorption site for protein and peptide drugs.
 Used to prolong the drug therapy.
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5. ANATOmy & PhySiOlOgy Of
COlON
GIT:
•Stomach
•Small intestine
•Large intestine
COLON:
Colon
 Rectum
 Anal canal
Colon consists:
• Cecum
• Ascending colon
• Transverse colon
• Descending colon
• Sigmoid colon
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6. lAyErS
:
•Serosa
•Muscularis externa
•Submucosa
•mucosa
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7. B R Nahata College of Pharmacy Mandsaur
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8. Factors governing the colon drug delivery
 Gastrointestinal transit
 Small intestinal transit
 Colonic transit
 Gastric emptying
 Stomach and intestinal pH
 Colonic micro flora and enzymes
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9. pH of GIT:
LOCATION Ph
1.STOMACH: 1.5-2.0
Fasted 3.0-5.0
Fed 5.0-6.5
2.SMALL INTESTINE: 6.0-7.5
Jejunum 6.4
Ileum 6.7-7.3
3.LARGE INTESTINE: 6.5-7.0
Right colon 6.6-7.0
Mid colon 6.6
Left colon 7.0
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10. Drug absorption in the colon
Drug molecules pass from the apical to
basolateral surface of the epithelial cell by
1. Transcellular - Passing through colonocytes.
2. paracellular - Passing between adjacent
colonocytes.
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11. ThE mAjOr fuNCTiONS
 The absorptive capacity is very high; each day about 2000
ml of fluid enters the colon through the ileocecal valve from
which more than 90% of the fluid is absorbed.
 Creation of a suitable environment for the growth of colonic
microorganisms, such as Bacteroides, Eubacterium, and
Enterobacteriaceae.
 Expulsion of the contents of the colon at a suitable time.
 Absorption of water and Na+ from the lumen, concentrating
the fecal content, and secretion of K+ ions
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12. AdvANTAgES
Drugs are directly available at the target site.
Comparatively lesser amount of required dose.
Decreased side effects.
Improved drug utilization.
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13. Pharmaceutical Approaches for Targeting
Drugs to Colon
pH sensitive systems
Microbially triggered system
◦ Prodrugs
◦ Polysaccharide based systems
Timed release systems
Osmotically controlled drug delivery
systems
Pressure dependent release systems
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14. pH sensitive systems
Solid formulations for colonic delivery that are
based on pH-dependent drug release mechanism
are similar to conventional enteric-coated
formulations.
Utilize enteric polymers that have relatively
higher threshold pH for dissolution.
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15. Polymers
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16. mEChANiSm Of ACTiON
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17. miCrObiAlly TriggErEd SySTEmS
Bacterial count in the colon is much
higher around 1011-1012 CFU/ml.
 400 species
 Fundamentally anaerobic in nature.
 Predominant species: Bacteroides,
Bifidobacterium and Eubacterium.
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18. Major metabolic processes occurring in the colon
are hydrolysis and reduction
ENzymES iN COlON
Reducing enzymes Hydrolytic enzymes
 Nitroreductase Esterases
 Azoreductase Amidases
 N-oxide reductase Glycosidases
 Sulphoxide reductase Glucuronidase
 Hydrogenase Sulfatase
 Azoreductases, which reduces azo-bonds selectively and
 Polysaccharidases which degrades the polysaccharides
.
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19. AzObONd PrOdrugS
Hydrolysis of sulphasalazine (i) into 5-aminosalicylic acid (ii) and
sulfapyridine (iii). B R Nahata College of Pharmacy Mandsaur
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20. glyCOSidE CONjugATES
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21. NATurAl POlySACChAridES AS
POlymEr fOr COlON drug
dElivEry
Chitoson
Pectin
Guar gum
Chondroitin sulphate
Dextran
Almond gum
Locust bean gum
Cyclodextrins
Inulin
Boswellia gum
Khaya gum B R Nahata College of Pharmacy Mandsaur
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22. Enteric-coated polysaccharide matrix
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23. Compression Coated Tablets
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24. Mixed Film Coated Tablets
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25. TimEd rElEASE SySTEmS
 Releases the drug after a predetermined
lag time
The lag time usually starts after gastric
emptying because most of the time-
controlled formulations are enteric
coated
Drug release from these systems is not
pH dependent
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26. B R Nahata College of Pharmacy Mandsaur
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27. OSmOTiCAlly CONTrOllEd drug
dElivEry SySTEmS
Delivery port
Rigid semi permeable membrane
Osmotic agent layer
Fluid to be pumped
Depend up on the osmotic pressure exerted by Depend
osmogen on drug compartment with which though drug get
released slowly though the orifice
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28. Pressure DePenDent release
systems
 Relies on the relatively strong peristaltic waves
in the colon that lead to an increased luminal
pressure, in response to raised pressure of the
colon the dosage form get ruptured and release
the drug at desired site
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29. Platform Technologies for
CTDDS
• PULSINCAP
• OROS-CT
• CODESTM
• CHRONOTROPIC® SYSTEM
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30. PULSINCAP
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31. OrOS-CT
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32. COdES Tm
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33. ChrONOTrOPiC® SySTEm
Enteric coat
Drug containing core
HPMC Coat
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34. EvAluATiON
Invitro models
Invitro test for intactness of coating and carriers in simulated
conditions of stomach and intestine
step1
Drug release study in 0.1N HCL for 2 hours (mean gastric
emptying)
step 2
Drug release study in phosphate buffer for 3 hours (mean
small intestine transit time)
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35. In vitro enzymatic degradation
test
Method 1:
Drug release in buffer medium containing enzymes(e.g.pectinase,
dextranase) or rat or guinea pig or rabbit decal contents
Amount of drug release in particular time directly proportional to
the rate of degradation of polymer carrier.
Method 2:
Incubating carrier drug system in fermenter
Suitable medium containing colonic bacteria (streptococcus
faecium or B.ovatus)
Amount of drug released at different time intervels determined .
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36. Clinical evaluation of
colon-specific drug
delivery system
• Gamma Scintigraphy
• High-frequency capsule
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37. Gamma Scintigraphy showing the spread of the tracer all
along the ascending, transverse, descending and sigmoid
colon
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38. High-frequency capsule method:
 Therelative BA of CDDS can be evaluated by high
frequency capsules
smoth plastic capsule containing
small latex bollon, drug and
radiotracer taken orally
Triggering system
(high frequency generator)
Release of drug and radiotracer
Triggered by an impules, the release is monitered
In different parts of GIT by
Radiological localization
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39. CONCluSiON
 The colonic region of the GIT has become an
increasingly important site for drug delivery and
absorption.
 CDDS offers therapeutic benefits to patients in both
local and systemic treatment.
 Systems utilize natural materials that are degraded by
colonic bacterial enzymes.
 Colon provides favorable factors and conditions for
designing of delivery systems.
 High commercial viability. Increasing number of
international patents and research work in this particular
mode of drug delivery itself shows its potential for
pharmaceutical market.
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40.  S.P. Vyas, R.K. Khar ; controlled Drug Delivery
 N.K.JAIN; Progress in controlled and novel drug
delivery systems.
 Vincent H.L. Lee and Suman k. Mukherjee ;
Encyclopedia of pharmaceutical Technology. Edi 2007
 Van den Mooter G. V., Kinget R, (1995) Oral colon-
specific drug delivery: a review DrugDeliv, 2: 81-93.
 Sarasija S, Hota A. (2002) Colon-specific drug delivery
systems. Ind J Pharm Sci. 62(1):1-8.
 Colon targeted drug delivery system: A Review on
primary and novel approaches.Oman Medical J,volume
25, issue 2, april2010.
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41. Colon-specific drug delivery system:
IJPS,2000,62,1-8.
Oral colon targeted delivery systems for
treatment of IBD: synthesis,in vitro and invivo
assessment-IJPharm 358(2008)248-255.
Novel Pharmaceutical Approaches for Colon
Drug Delivery: An overview- Journal of
Pharmacy Research, july-sep 2008
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42. ThANK yOu
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