Alkylating agent used in chemotherapy:
**Core Concept**
Cyclophosphamide is a type of alkylating agent used in chemotherapy. Alkylating agents work by adding an alkyl group to the DNA of cancer cells, thereby interfering with their replication and inducing cell death. This mechanism is crucial for the treatment of various types of cancer.
**Why the Correct Answer is Right**
Cyclophosphamide is metabolized in the liver to its active form, which then crosses the cell membrane and reacts with DNA to form cross-links. This reaction prevents DNA replication and transcription, ultimately leading to cell death. The mechanism of action of cyclophosphamide involves the formation of DNA adducts, which are responsible for its cytotoxic effects.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because 5-fluorouracil is an antimetabolite, not an alkylating agent. Antimetabolites interfere with DNA and RNA synthesis by substituting for normal bases.
**Option B:** This option is incorrect because doxorubicin is an anthracycline antibiotic that intercalates DNA, thereby inhibiting topoisomerase II and inducing cell death. It is not an alkylating agent.
**Option C:** This option is incorrect because cisplatin is a platinum-based alkylating agent, but it works by forming platinum-DNA adducts, which is a different mechanism of action compared to cyclophosphamide.
**Clinical Pearl / High-Yield Fact**
When administering cyclophosphamide, it is essential to give mesna (sodium 2-sulfanylethanesulfonate) to prevent hemorrhagic cystitis, a common side effect of this medication. Mesna works by conjugating with acrolein, a toxic metabolite of cyclophosphamide.
**Correct Answer:** C. Cyclophosphamide