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Questions and Answers
What is the primary advantage of colon mucosa in terms of proteolytic activity?
What is the primary criteria for selecting a drug for Colon-Targeted Drug Delivery Systems (CDDS)?
Which type of CDDS is dependent on the pH of the gastrointestinal tract?
What is the primary mechanism of Transit Time Dependent CDDS?
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What is the primary advantage of using enteric materials in CDDS?
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Which type of CDDS is dependent on the enzymatic activity of bacterial enzymes in the colon?
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What is the primary mechanism of Osmotic Pressure-Controlled CDDS?
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What is the primary advantage of using polymeric coatings in CDDS?
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What is the primary disadvantage of Transit Time Dependent CDDS?
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What is the primary criteria for selecting a drug for CDDS in terms of first-pass metabolism?
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Study Notes
Colon Targeted Drug Delivery Systems (CDDS)
- CDDS are gaining importance for systemic and local effects, especially for delivering proteins and peptides.
Anatomy of the Colon
- The colon is the final part of the digestive system, responsible for reabsorbing fluids and processing waste products.
- It consists of four parts: descending colon, ascending colon, transverse colon, and sigmoid colon.
Diseases of the Colon
- Ulcerative colitis
- Crohn's disease
- Colon cancer
- Amoebiasis
Importance of CDDS
- Reduced adverse side effects
- Useful for intentional delayed drug absorption
- Delivery of drug in its intact form close to the target site
Criteria for Selecting Drugs for CDDS
- Drugs poorly absorbed from the upper GIT
- Drugs that degrade in the stomach and small intestine
- Drugs that undergo extensive first-pass metabolism
- Drugs for colon cancer
Approaches to CDDS
1. pH- and Time-Dependent Colonic DDS
- The outer layer dissolves at pH > 5, then the intermediate swellable layer made of an enteric material.
- In another method, succinic acid is used as a pH-adjusting agent with the drug substance in a hard gelatin capsule.
2. pH- and Time-Dependent Colonic DDS
- The outermost enteric layer prevents drug release in the stomach, and the hydrophilic layer dissolves quickly after gastric emptying.
- The onset time of drug release in the intestine can be controlled by the thickness of the acid-soluble layer.
3. Bacterial Enzyme-Dependent Colonic DDS
- The microflora of the colon (10^11-10^12 CFU/ml) produces enzymes that enhance the use of biodegradable polymers for CDDS.
- These polymers shield the drug from the stomach and small intestine and deliver it to the colon, where they undergo assimilation or degradation.
4. pH and Bacterial Enzyme-Dependent Colonic DDS (CODES System)
- The CODES system is a unique CDDS technology that avoids problems associated with pH or time-dependent systems.
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Description
This quiz covers the design and functionality of pH-dependent colonic drug delivery systems, including the use of enteric materials and acid-soluble polymers. It explores the release of drug substances in the colon and the role of pH-adjusting agents.
