Questions and Answers
What is one of the primary therapeutic advantages of targeting drug delivery to the colon?
What is mesalamine primarily used for?
Which type of bond in drugs such as balsalazide facilitates their degradation by anaerobic microbes?
What is a key factor affecting drug availability in the colon?
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Why are protein drugs generally unstable when administered orally?
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What characteristic of the human colon contributes to the low availability of drugs for absorption?
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Which of the following factors is NOT mentioned as influencing drug delivery to the colon?
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What do researchers aim to achieve by protecting protein and peptide drugs during oral delivery?
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What is one of the key benefits of rectal drug delivery compared to oral administration?
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Which of the following drugs is mentioned as being suitable for colonic delivery?
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What is a disadvantage of rectal drug delivery?
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Which component is likely to affect the rate of drug absorption in rectal drug delivery?
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What type of base generally allows for the dissolution and release of drug in a suppository?
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Which drug form is specifically mentioned for rectal and vaginal drug delivery?
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What is the purpose of prodrugs such as naproxen–dextran?
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Which of the following factors is NOT mentioned as impacting absorption in rectal drug delivery?
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What type of drug is specifically mentioned for colon-targeted delivery by oral administration?
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What characteristic is essential for the sustained release preparation for rectal administration?
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Study Notes
Colonic Drug Delivery
- Colonic drug delivery targets drugs that are unstable in the stomach's acidic environment or susceptible to enzymatic metabolism.
- Therapeutic advantages include improved treatment of local diseases like Crohn's disease.
- Mesalamine (5-ASA) is delivered via a delayed-release tablet, designed to release the drug post-distal ileum.
- Prodrugs such as sulfasalazine and balsalazine help deliver 5-ASA for localized chemotherapy in inflammatory bowel disease (IBD).
- Azo bonds in drugs (e.g., balsalazide) are broken down by anaerobic bacteria in the lower bowel.
- Oral delivery of proteins and therapeutic peptides (e.g., insulin) is being investigated, as they degrade in the stomach and small intestine.
- Successful colonic delivery depends on high bacterial presence, colonic physiology, fluid levels, and transit time.
- The human colon hosts over 500 species of bacteria, with counts reaching 10^12/mL, influencing drug metabolism.
- Some drugs (e.g., beta-blockers, NSAIDs, steroids) are well absorbed in the colon, similar to small intestine absorption, making them suitable for colonic delivery.
- Naproxen can be administered as a prodrug (naproxen-dextran) that withstands intestinal enzymes and is activated in the colon.
Rectal and Vaginal Drug Delivery
- Rectal and vaginal drug products can be in solid or liquid forms, serving both local and systemic purposes.
- Rectal administration is beneficial when oral intake is intolerable or impractical (e.g., nausea, during seizures).
- Advantages of rectal delivery include rapid absorption of low-molecular weight drugs, partial avoidance of first-pass metabolism, and potential lymphatic absorption.
- Challenges with this route involve inconsistent drug absorption, dissolution issues, and microbial metabolism.
- Various adjuvants and surfactants have been researched to enhance absorption via rectal administration.
- Factors affecting rectal absorption include drug formulation, concentration, rectal pH, stool presence, and fluid volume.
- Sustained-release formulations are developed for rectal use, with release rates influenced by the suppository base composition.
- Water-soluble bases (e.g., polyethylene glycol) dissolve and release drugs, while oleaginous bases release drugs when melted at body temperature.
- Vaginal drug delivery utilizes specialized systems for both local and systemic therapeutic applications, offering a versatile route for medication administration.
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Description
Explore the various techniques involved in colonic drug delivery, highlighting its therapeutic advantages for treating local diseases of the lower bowel and colon, like Crohn’s disease. This quiz will also cover examples of drug formulations designed to withstand gastric conditions.
