Question

A patient develops mouth ulcers on treatment with Methotrexate. Which of the following will decrease with this drug?

• A. UMP
• B. TMP
• C. CMP

Hint:

Methotrexate inhibits folate metabolism, leading to reduced TMP, which is necessary for DNA synthesis, contributing to side effects like mouth ulcers.

Answer 1

The Correct Option is B

Methotrexate is a medication commonly used in chemotherapy and as an immunosuppressant. It works as a folate antagonist, specifically by inhibiting the enzyme dihydrofolate reductase (DHFR). This enzyme is crucial for the formation of tetrahydrofolate, a coenzyme involved in the synthesis of the nucleotide thymidylate (TMP), a precursor for DNA synthesis. When DHFR is inhibited, the conversion of dihydrofolate to tetrahydrofolate is decreased, leading to a reduction in the production of TMP:

1. Mechanism: Methotrexate decreases the availability of tetrahydrofolate, impacting the synthesis of thymidylate, a necessary component for DNA replication and repair.
2. Effect on Thymidylate: Since TMP (thymidine monophosphate) is synthesized from thymidylate, a decrease in tetrahydrofolate results in decreased TMP production.
3. Clinical Implication: The decreased synthesis of TMP affects rapidly dividing cells, leading to side effects such as mouth ulcers.

In conclusion, the drug Methotrexate specifically decreases the levels of TMP (thymidylate), which correlates with its effect on mouth ulcers. Thus, the correct answer is TMP.