Drug which doesn’t inhibit nucleic acid synthesis?
**Core Concept**
Nucleic acid synthesis inhibitors are a class of drugs that target enzymes involved in DNA or RNA production, often used in cancer chemotherapy. These drugs work by blocking the action of enzymes such as thymidylate synthase, dihydrofolate reductase, or ribonucleotide reductase.
**Why the Correct Answer is Right**
The correct answer is a drug that does not interfere with nucleic acid synthesis, meaning it does not target enzymes involved in DNA or RNA production. This is in contrast to drugs like methotrexate, which inhibits dihydrofolate reductase and thereby impairs thymidine synthesis. Other examples of nucleic acid synthesis inhibitors include 5-fluorouracil and gemcitabine.
**Why Each Wrong Option is Incorrect**
* **Option A:** This drug, such as methotrexate, inhibits dihydrofolate reductase and thereby impairs thymidine synthesis, affecting nucleic acid production.
* **Option B:** This drug, such as 5-fluorouracil, works by inhibiting thymidylate synthase, a key enzyme in DNA synthesis.
* **Option C:** This drug, such as gemcitabine, is a nucleoside analog that inhibits ribonucleotide reductase, an enzyme crucial for RNA production.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that nucleic acid synthesis inhibitors are a crucial class of chemotherapeutic agents, but they often have severe side effects due to their mechanism of action, which can lead to bone marrow suppression and other toxicities.
**Correct Answer:** D.