<prompt> Extracellular adenosine is increased by which of the following DMARDs?LeflunomideSulphasalazineMethotrexateHydroxychloroquine  <response>: Methotrexate: Methotrexate inhibits an enzyme 5-aminoimidazole-4-carboxamide ribonucleotide AICAR transformylase leading to accumulation of AICAR, which blocks adenosine deaminase. Thus adenosine accumulates and it decreases inflammation by acting on adenosine receptors. 