ICD-10 Specific code K51: Ulcerative colitis

Beclometasone is a pro-drug with weak glucocorticoid receptor binding affinity. It is extensively hydrolysed via esterase enzymes to the active metabolite beclometasone-17-monopropionate (B-17-MP), which has potent topical anti-inflammatory activity.

Etrasimod is a sphingosine-1-phosphate (S1P) receptor modulator that binds to S1P receptors 1, 4 and 5 (S1P_1,4,5) and is a balanced G-protein and beta-arrestin agonist at S1P₁. Etrasimod has minimal activity on S1P₃ and no activity on S1P2. Etrasimod partially and reversibly blocks the capacity of lymphocytes to egress from lymphoid organs, reducing the number of lymphocytes in peripheral blood thereby lowering the number of activated lymphocytes in the tissue. The mechanism by which etrasimod exerts therapeutic effects in ulcerative colitis is unknown but may involve the reduction of lymphocyte migration into sites of inflammation.

Infliximab is a chimeric human-murine monoclonal antibody that binds with high affinity to both soluble and transmembrane forms of TNFα but not to lymphotoxin α (TNFβ).

Mesalazine is an aminosalicylate. The mechanism of action of mesalazine is not fully understood, but appears to have a topical anti-inflammatory effect on the colonic epithelial cells. Mucosal production of arachidonic acid metabolites, both through the cyclooxygenase and lipoxygenase pathways, is increased in patients with chronic inflammatory bowel disease, and it is possible that mesalazine diminishes inflammation by blocking cyclooxygenase and inhibiting prostaglandin production in the colon.

Methylprednisolone is a synthetic glucocorticoid and a methyl derivative of prednisolone. Methylprednisolone is a potent anti-inflammatory agent with the capacity to profoundly inhibit the immune system.

Therapeutic benefit of sulfasalazine appears to be due to a local action of the sulfasalazine and its split product 5-aminosalicylic acid on the mucous membrane and deeper colonic structures.

Tofacitinib is a potent, selective inhibitor of the JAK family. In human cells, tofacitinib preferentially inhibits signalling by heterodimeric cytokine receptors that associate with JAK3 and/or JAK1. Inhibition of JAK1 and JAK3 by tofacitinib attenuates signalling of interleukins and type I and type II interferons, which will result in modulation of the immune and inflammatory response.