What is the metabolism and MOA of SSZ?
Only 10% to 30% of SSZ is ultimately absorbed in the small intestine. Most SSZ is broken down by colonic bacteria to sulfapyridine, which is then 90% absorbed, and into 5-ASA, which mostly (90%) stays in the bowel. The sulfapyridine component is felt to be most effective and thus patients without a colon may not respond to SSZ. SSZ has multiple antiinflammatory (including upregulation of adenosine similar to MTX) and immunomodulatory effects (via interaction on the gut immune system), but the exact MOA is unknown.