indication

For the treatment of Inflammatory Bowel Disease and Ulcerative Colitis.

pharmacology

Olsalazine is an anti-inflammatory drug used in the treatment of Inflammatory Bowel Disease and Ulcerative Colitis. Olsalazine reduces the bowel inflammation, diarrhea (stool frequency), rectal bleeding, and abdominal pain. Like Balsalazide, Olsalazine is believed to deliver Mesalazine, or 5-aminosalicylic acid (5-ASA), past the small intestine, directly to the large intestine, which is that active site of disease in ulcerative colitis.

mechanism of action

Orally administered olsalazine is converted to mesalamine which is thought to be the therapeutically active agent in the treatment of ulcerative colitis. The mechanism of action of mesalamine (and sulfasalazine) is unknown, but appears to be topical rather than systemic. Mucosal production of arachidonic acid (AA) metabolites, both through the cyclooxygenase pathways, i.e., prostanoids, and through the lipoxygenase pathways, i.e., leukotrienes (LTs) and hydroxyelcosatetraenoic acids (HETEs) is increased in patients with chronic inflammatory bowel disease, and it is possible that mesalamine diminishes inflammation by blocking cyclooxygenase and inhibiting prostaglandin (PG) production in the colon.

toxicity

Maximum single oral doses of 5g/kg in mice and rats and 2 g/kg in dogs were not lethal.

biotransformation

Most (98 to 99%) of an oral dose is rapidly converted into two molecules of 5-aminosalicylic acid (5-ASA) by colonic bacteria and the low prevailing redox potential found in this environment. The conversion of olsalazine to mesalamine in the colon is similar to that of sulfasalazine, which is converted into sulfapyridine and mesalamine. Approximately 0.1% of an oral dose of olsalazine is metabolized in the liver to olsalazine-O-sulfate (olsalazine-S)

absorption

After oral administration, olsalazine, has limited systemic bioavailability. 98-99% of the dose is converted to mesalamine (5-ASA) in the colon, which is absorbed slowly resulting in very high local concentrations in the colon.

half life

Olsalazine has an elimination half-life of 0.9 hours, however, olsalazine-S has a half-life of 7 days.

route of elimination

Approximately 0.1% of an oral dose of olsalazine is metabolized in the liver to olsalazine-O-sulfate (olsalazine-S).The remaining 5-ASA is partially acetylated and is excreted in the feces.

drug interactions

Azathioprine: Olsalazine may increase the toxicity of thiopurine, azathioprine.

Mercaptopurine: Olsalazine may increase the toxicity of thiopurine, mercaptopurine.

Thioguanine: Olsalazine may increase the toxicity of thiopurine, thioguanine.