Question:
Interaction of Methotrexate with sulfonamides (such as Sulfamethoxazole and Sulfisoxazole) may lead to which type of drug interaction
Interaction of Methotrexate with sulfonamides (such as Sulfamethoxazole and Sulfisoxazole) may lead to which type of drug interaction
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Sulfonamides are "bullies" on albumin—they displace Methotrexate and Warfarin.
Updated On: May 25, 2026
- Reduced absorption of methotrexate
- Methotrexate direct folate antagonist
- Displacement of methotrexate from plasma protein-binding sites
- Increased renal excretion of methotrexate
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The Correct Option is C
Solution and Explanation
Step 1: Concept
Pharmacokinetic drug interactions can occur at the level of distribution, specifically regarding plasma protein binding.
Step 2: Meaning
Displacement occurs when one drug with higher affinity for albumin "kicks off" another drug, increasing the free, active fraction of the displaced drug.
Step 3: Analysis
Methotrexate is highly protein-bound. Sulfonamides can displace methotrexate from these binding sites. Additionally, sulfonamides can inhibit the renal tubular secretion of methotrexate.
Step 4: Conclusion
The primary interaction mentioned in common competitive binding scenarios is the displacement from plasma proteins, leading to potential toxicity. Final Answer: (C)
Pharmacokinetic drug interactions can occur at the level of distribution, specifically regarding plasma protein binding.
Step 2: Meaning
Displacement occurs when one drug with higher affinity for albumin "kicks off" another drug, increasing the free, active fraction of the displaced drug.
Step 3: Analysis
Methotrexate is highly protein-bound. Sulfonamides can displace methotrexate from these binding sites. Additionally, sulfonamides can inhibit the renal tubular secretion of methotrexate.
Step 4: Conclusion
The primary interaction mentioned in common competitive binding scenarios is the displacement from plasma proteins, leading to potential toxicity. Final Answer: (C)
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