DIPENTUM- olsalazine sodium capsule
UCB, Inc.
DESCRIPTION
The active ingredient in DIPENTUM Capsules (olsalazine sodium) is the sodium salt of a salicylate, disodium 3,3?-azobis (6-hydroxybenzoate) a compound that is effectively bioconverted to 5-aminosalicylic acid (5-ASA), which has anti-inflammatory activity in ulcerative colitis. Its empirical formula is C14 H8 N2 Na2 O6 with a molecular weight of 346.21.
The structural formula is:
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Olsalazine sodium is a yellow crystalline powder, which melts with decomposition at 240�C. It is the sodium salt of a weak acid, soluble in water and DMSO, and practically insoluble in ethanol, chloroform, and ether. Olsalazine sodium has acceptable stability under acidic or basic conditions.
DIPENTUM is supplied in hard gelatin capsules for oral administration. The inert ingredient in each 250 mg capsule of olsalazine sodium is magnesium stearate. The capsule shell contains the following inactive ingredients: black iron oxide, caramel, gelatin, and titanium dioxide.
CLINICAL PHARMACOLOGY
After oral administration, olsalazine has limited systemic bioavailability. Based on oral and intravenous dosing studies, approximately 2.4% of a single 1.0 g oral dose is absorbed. Less than 1% of olsalazine is recovered in the urine. The remaining 98 to 99% of an oral dose will reach the colon, where each molecule 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 liberated 5-ASA is absorbed slowly resulting in very high local concentrations in the colon.
The conversion of olsalazine to mesalamine (5-ASA) in the colon is similar to that of sulfasalazine, which is converted into sulfapyridine and mesalamine. It is thought that the mesalamine component is therapeutically active in ulcerative colitis (A.K. Azad-Kahn et al, LANCET , 2: 892-895, 1977). The usual dose of sulfasalazine for maintenance of remission in patients with ulcerative colitis is 2 grams daily, which would provide approximately 0.8 grams of mesalamine to the colon. More than 0.9 grams of mesalamine would usually be made available in the colon from 1 gram of olsalazine.
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 hydroxyeicosatetraenoic 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.
