Methotrexate, a medication commonly used to treat conditions such as rheumatoid arthritis, psoriasis, and certain types of cancer, has been found to interact with other medications, potentially altering their efficacy [1]. These interactions can result in decreased or increased effectiveness of the co-administered drugs, which can have significant implications for patients.

Methotrexate interferes with the metabolism of certain folic acid-dependent enzymes, which can affect the way other medications are metabolized in the body [1]. This can lead to decreased efficacy of co-administered drugs, as they may not be properly metabolized or activated, or increased efficacy, as they may accumulate in the body due to decreased clearance.

For example, methotrexate has been found to decrease the efficacy of certain antibiotics, such as penicillins and tetracyclines, by inhibiting their bactericidal activity [1]. On the other hand, methotrexate can increase the efficacy of certain nonsteroidal anti-inflammatory drugs (NSAIDs), such as naproxen and sulindac, by increasing their bioavailability and half-life [1].

It is important for healthcare providers to be aware of these potential interactions and to closely monitor patients taking methotrexate in combination with other medications. Dosages may need to be adjusted, and patients should be closely monitored for signs of decreased or increased efficacy of their co-administered drugs.

In conclusion, methotrexate can alter the efficacy of co-administered medications by interfering with their metabolism. Healthcare providers should be aware of these potential interactions and closely monitor patients taking methotrexate in combination with other drugs.

Sources:
[1] DrugPatentWatch.com. (n.d.). Methotrexate Drug Interactions. Retrieved from <https://www.drugpatentwatch.com/drugs/methotrexate/interactions>