The effect of pH on drug absorption 5. Many drugs are absorbed into the blood through cells lining the stomach, the small intestine, or other epithelial tissues. This process involves movement of the drug molecule across the plasma membrane by direct diffusion. Since the interior of the plasma membrane is hydrophobic, the uncharged molecules cross the membrane faster than charged (ionized) molecules. If a drug contains an ionizable group, its absorption will therefore be dependent on the pH. Consider the absorption of the ionizable drug, morphine, shown below in its uncharged form. We will only focus on the ionization of the amino group of morphine (pKa = 8.2). НО.
The effect of pH on drug absorption 5. Many drugs are absorbed into the blood through cells lining the stomach, the small intestine, or other epithelial tissues. This process involves movement of the drug molecule across the plasma membrane by direct diffusion. Since the interior of the plasma membrane is hydrophobic, the uncharged molecules cross the membrane faster than charged (ionized) molecules. If a drug contains an ionizable group, its absorption will therefore be dependent on the pH. Consider the absorption of the ionizable drug, morphine, shown below in its uncharged form. We will only focus on the ionization of the amino group of morphine (pKa = 8.2). НО.
Related questions
Question
Transcribed Image Text:**The effect of pH on drug absorption**
Many drugs are absorbed into the blood through cells lining the stomach, the small intestine, or other epithelial tissues. This process involves movement of the drug molecule across the plasma membrane by direct diffusion. Since the interior of the plasma membrane is hydrophobic, the uncharged molecules cross the membrane faster than charged (ionized) molecules. If a drug contains an ionizable group, its absorption will therefore be dependent on the pH. Consider the absorption of the ionizable drug, morphine, shown below in its uncharged form. We will only focus on the ionization of the amino group of morphine (pKa = 8.2).
The diagram illustrates two states of the morphine molecule:
- **Morphine (neutral)**: The structure shows the morphine molecule in its uncharged form.
- **Morphine (charged)**: Not explicitly shown in the image, but it refers to the ionized form when the amino group is charged.
This explanation highlights the relationship between pH and the ionization state of drugs like morphine, impacting their absorption in the body.
![**Educational Content: pH-Dependent Morphine Ionization**
---
**a. Question:**
In the neutral form shown above, is morphine in its HA or \(A^-\) state?
**b. Task:**
On the diagram above, draw the charged form of morphine.
**c. Calculation Challenge:**
- The pH in the stomach is approximately 2.0, and in the intestine, it is approximately 7.4.
- Calculate what proportion of morphine will be in its neutral form in the stomach and in the intestine. Use the ratio of neutral/charged species.
- Complete the table and show your work.
| **neutral/charged morphine\*** | | |
|--------------------------------|---|---|
| stomach | | |
| intestine | | |
\**Note: this is either [HA]/[A⁻] or [A⁻]/[HA], depending on your answers in (a) and (b).*
**d. Analysis and Prediction:**
Using your result in part (c) of this question, predict if morphine is absorbed more efficiently in the stomach or in the intestine. Explain your reasoning.
---
*End of Educational Content Section.*](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F9e38577e-9620-4c07-818f-a04b4c1cdbce%2Fb631b03e-c42b-4863-88a6-f3e515e718c3%2F1cobx4n_processed.png&w=3840&q=75)
Transcribed Image Text:**Educational Content: pH-Dependent Morphine Ionization**
---
**a. Question:**
In the neutral form shown above, is morphine in its HA or \(A^-\) state?
**b. Task:**
On the diagram above, draw the charged form of morphine.
**c. Calculation Challenge:**
- The pH in the stomach is approximately 2.0, and in the intestine, it is approximately 7.4.
- Calculate what proportion of morphine will be in its neutral form in the stomach and in the intestine. Use the ratio of neutral/charged species.
- Complete the table and show your work.
| **neutral/charged morphine\*** | | |
|--------------------------------|---|---|
| stomach | | |
| intestine | | |
\**Note: this is either [HA]/[A⁻] or [A⁻]/[HA], depending on your answers in (a) and (b).*
**d. Analysis and Prediction:**
Using your result in part (c) of this question, predict if morphine is absorbed more efficiently in the stomach or in the intestine. Explain your reasoning.
---
*End of Educational Content Section.*
Expert Solution
This question has been solved!
Explore an expertly crafted, step-by-step solution for a thorough understanding of key concepts.
Step by step
Solved in 3 steps with 2 images
