Methotrexate is a commonly prescribed medication for the treatment of rheumatoid arthritis, psoriasis, and cancer. However, it is important to consider the potential interactions with other medications when prescribing it to elderly patients.

According to DrugPatentWatch [1], methotrexate has a moderate interaction with nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen and aspirin. These drugs can increase the risk of methotrexate toxicity, including liver damage, and should be used with caution. Similarly, methotrexate should not be used with other hepatotoxic drugs, such as acetaminophen and alcohol, as they can also increase the risk of liver damage.

A study published in the Journal of Pharmacy Practice [2] notes that methotrexate can also interact with medications commonly prescribed to elderly patients, such as proton pump inhibitors (PPIs) and antibiotics. PPIs can decrease the absorption of methotrexate, while antibiotics such as trimethoprim-sulfamethoxazole can increase the risk of methotrexate toxicity.

The FDA-approved label for methotrexate [3] also notes that it can interact with certain medications, including penicillins, tetracyclines, and oral contraceptives. These medications can decrease the effectiveness of methotrexate or increase the risk of toxicity.

In summary, methotrexate can interact with several medications commonly prescribed to elderly patients, including NSAIDs, PPIs, antibiotics, and other hepatotoxic drugs. Therefore, it is important for healthcare providers to carefully consider these potential interactions when prescribing methotrexate to elderly patients and to monitor them closely for any adverse effects.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/METHOTREXATE
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5871236/
[3] https://www.accessdata.fda.gov/drugsatfda_docs/label/2016/008085s066lbl.pdf