As a clinical pharmacist, you should always be aware of drug interactions. There's concern that caffeine might reduce the efficacy of methotrexate for rheumatoid arthritis...
Methotrexate decreases inflammation by increasing adenosine levels. Caffeine might cause a problem, because it's an adenosine receptor ANTAGONIST. It's going to take time to figure out how significant this is.
In the meantime, if your methotrexate patients aren't improving, suggest they decrease caffeine consumption to less than 120 mg/day, about one cup of coffee. Remind them to count the caffeine in teas, soft drinks and herbals that contain guarana, cola nut, etc. FOR MORE INFORMATION, SEE OUR NOTE "Overview of rheumatoid arthritis".
REFERENCES
-
Nesher G, Mates M, Zevin S. Effect of caffeine consumption on efficacy of methotrexate in rheumatoid arthritis. Arthritis Rheum. 2003 Feb;48(2):571-2. Available at: https://pubmed.ncbi.nlm.nih.gov/12571869
Cutolo M, Sulli A, Pizzorni C, Seriolo B, Straub RH. Anti-inflammatory mechanisms of methotrexate in rheumatoid arthritis. Ann Rheum Dis. 2001 Aug;60(8):729-35. Available at: https://pubmed.ncbi.nlm.nih.gov/11454634