See the DrugPatentWatch profile for methotrexate

Methotrexate, a medication used primarily to treat cancer and autoimmune diseases, can interact with other drugs, potentially affecting their potency. According to the National Center for Biotechnology Information (NCBI) [2], methotrexate can reduce the efficacy of certain medications by inhibiting the enzyme dihydrofolate reductase, which is necessary for the synthesis of purines and thymidylates, crucial components for DNA replication.

One such drug that can be affected is the antibiotic trimethoprim-sulfamethoxazole (TMP-SMX) [2]. Methotrexate can increase TMP-SMX levels in the body, potentially leading to toxicity. Therefore, patients taking both medications may require dose adjustments or closer monitoring.

Additionally, methotrexate can interact with non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen and naproxen [1][2]. Concurrent use can increase the risk of kidney damage and stomach ulcers.

Furthermore, methotrexate can interact with certain anticonvulsant drugs, such as phenytoin and levetiracetam [2]. Methotrexate can increase phenytoin levels, leading to toxicity, while levetiracetam levels can be decreased, reducing its effectiveness.

Lastly, methotrexate can interact with live vaccines, reducing their efficacy and increasing the risk of adverse effects [3]. Therefore, it is generally recommended to avoid live vaccines while on methotrexate.

In conclusion, methotrexate can interact with various medications, potentially affecting their potency. Patients should inform their healthcare providers of all medications they are taking to avoid potential interactions.

Sources:
[1] <https://www.drugpatentwatch.com/p/tradename/METHOTREXATE>
[2] <https://www.ncbi.nlm.nih.gov/books/NBK556114/>
[3] <https://pubmed.ncbi.nlm.nih.gov/37440131/>