Methotrexate is what class of anti cancer drug ?
**Core Concept**
Methotrexate is an antifolate drug that acts as an antineoplastic agent, which means it is used to treat cancer. It works by inhibiting the enzyme dihydrofolate reductase (DHFR), which is crucial for the synthesis of tetrahydrofolate, a necessary cofactor for DNA synthesis and repair.
**Why the Correct Answer is Right**
Methotrexate is classified as an antimetabolite, a class of drugs that inhibit the metabolism of cancer cells. By blocking the action of DHFR, methotrexate prevents the production of tetrahydrofolate, thereby inhibiting DNA synthesis and cell division in rapidly growing cancer cells. This mechanism of action makes methotrexate effective in treating various types of cancer, including leukemia, lymphoma, and solid tumors.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because methotrexate does not act as an alkylating agent, which is a different class of antineoplastic drugs that work by adding an alkyl group to the DNA of cancer cells, thereby causing cross-linking and cell death.
**Option B:** This option is incorrect because methotrexate does not work by inhibiting topoisomerase, an enzyme involved in DNA replication and transcription. Inhibitors of topoisomerase, such as doxorubicin, are a different class of antineoplastic drugs.
**Option C:** This option is incorrect because methotrexate does not act as a platinum-based chemotherapeutic agent, which is a class of drugs that work by forming platinum-DNA adducts that inhibit DNA replication and transcription.
**Clinical Pearl / High-Yield Fact**
Methotrexate is also used as an immunosuppressive agent in the treatment of autoimmune diseases, such as rheumatoid arthritis and psoriasis. This is due to its ability to inhibit the proliferation of T cells and other immune cells.
**Correct Answer:** C.