Podcast
Questions and Answers
A drug administered in solid form with poor aqueous solubility is likely to have its absorption limited by which factor?
A drug administered in solid form with poor aqueous solubility is likely to have its absorption limited by which factor?
- Surface area of the stomach epithelium.
- The concentration of the drug at the absorption site.
- The rate of dissolution. (correct)
- Blood flow to the absorption site.
Why are weakly acidic drugs generally better absorbed in the stomach compared to the small intestine?
Why are weakly acidic drugs generally better absorbed in the stomach compared to the small intestine?
- The pH of the stomach favors the non-ionized form of weakly acidic drugs. (correct)
- The pH of the stomach favors the ionized form of weakly acidic drugs.
- The surface area of the stomach is greater than that of the small intestine.
- The pH of the small intestine is more acidic than the stomach.
Despite the stomach's ability to better absorb weak acids, absorption is generally greater in the small intestine. Which factor contributes most to this?
Despite the stomach's ability to better absorb weak acids, absorption is generally greater in the small intestine. Which factor contributes most to this?
- The significantly larger surface area provided by the villi in the small intestine. (correct)
- The pH of the small intestine is more conducive to drug stability.
- Blood flow is greater in the stomach.
- The thick mucosal layer of the stomach hinders absorption.
Which statement accurately describes the relationship between gastric emptying and drug absorption?
Which statement accurately describes the relationship between gastric emptying and drug absorption?
If a drug is primarily absorbed in its non-ionized form via passive diffusion, what molecular property enhances its absorption?
If a drug is primarily absorbed in its non-ionized form via passive diffusion, what molecular property enhances its absorption?
A new drug is developed that is a weak base. Where is this drug likely to be absorbed best?
A new drug is developed that is a weak base. Where is this drug likely to be absorbed best?
How does the physical state of a drug (solution, suspension, or solid) affect its absorption in the gastrointestinal tract?
How does the physical state of a drug (solution, suspension, or solid) affect its absorption in the gastrointestinal tract?
What is the primary mechanism by which the majority of drug absorption occurs in the gastrointestinal tract?
What is the primary mechanism by which the majority of drug absorption occurs in the gastrointestinal tract?
A pharmaceutical company is formulating a new drug. To optimize absorption in the small intestine, which strategy should they prioritize, assuming the drug is stable in both acidic and alkaline environments?
A pharmaceutical company is formulating a new drug. To optimize absorption in the small intestine, which strategy should they prioritize, assuming the drug is stable in both acidic and alkaline environments?
A patient is taking a medication that significantly delays gastric emptying. How might this affect the absorption of another drug that is primarily absorbed in the small intestine?
A patient is taking a medication that significantly delays gastric emptying. How might this affect the absorption of another drug that is primarily absorbed in the small intestine?
Flashcards
Gastrointestinal absorption factors
Gastrointestinal absorption factors
Regulated by: absorption surface, blood flow, physical state (solution, suspension, solid), water solubility, and drug concentration at absorption site.
Solid drug absorption
Solid drug absorption
Dissolution rate can limit absorption, especially with low water solubility.
Passive Diffusion Favors
Passive Diffusion Favors
Passive diffusion favors absorption of non-ionized, lipophilic forms of drugs.
pH Partitioning Concept
pH Partitioning Concept
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Intestinal Absorption Advantage
Intestinal Absorption Advantage
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Gastric Emptying Rate
Gastric Emptying Rate
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Study Notes
- Oral administration involves absorption regulated by factors like absorption surface area, blood flow to the absorption site, the drug's physical state (solution, suspension, or solid), its water solubility, and concentration at the absorption site.
- The dissolution rate can limit the absorption of drugs administered in solid form, especially those with low water solubility.
- Most drug absorption in the gastrointestinal tract occurs through passive diffusion, which favors absorption of drugs in their non-ionized and more lipophilic form.
- Weakly acidic drugs are better absorbed in the stomach (pH 1-2) compared to the upper intestine (pH 3-6), while the opposite is true for weakly basic drugs, based on the pH partition concept.
- Despite the stomach's thick mucous layer and small surface area, the intestinal villi provide a vast surface area (approximately 200 m²).
- Consequently, drug absorption from the intestine is generally greater than from the stomach, even if the drug is mostly ionized in the intestine but largely non-ionized in the stomach.
- Factors accelerating gastric emptying likely increase drug absorption rate, while factors slowing gastric emptying should have the opposite effect, regardless of the drug's characteristics.
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