Anti-inflammatory; chemotaxis

Olsalazine affects intestinal electrolyte in a number of ways. When Olsalazine (< 2.89 mM) is applied in vitro, the ileal mucosa of rats and rabbits secretes more sodium and chloride ions and absorbs less of them. In the isolated rat colon, concentrations of olsalazine less than 11.5 mM also reduce net sodium and, to a greater extent, chloride absorption in a dose-dependent manner. The secretion of potassium also increases, but only up to a high concentration of 11.5 mM Olsalazine. In isolated rat jejunum, olsalazine also prevents the absorption of lactose and glucose.[1] Olsalazine, having an IC50 of 0.39 mM, is a strong inhibitor of the chemotaxis of human intestinal macrophages to LTB4. **[2]** By reduction of 31% and 73%, respectively, olsalazine (0.4 mM) inhibits the production of superoxide radicals produced by xanthine-xanthine oxidase reaction or by neutrophils activated by phorbol myristate acetate (PMA).[3] Further proposed mechanisms through which mesalazine derived from olsalazine may alleviate mucosal mucosa/inflammatory colonic conditions include suppression of colonic fatty acid oxidation, inhibition of platelet activating factor, inhibition of cytokine production in human mononuclear cells, inhibition of endothelial cell proliferation by folic acid antagonism, inhibition of leukotriene synthesis from arachidonic acid via inhibition of lipoxygenase, as well as other potential mechanisms.[4] modification of the prostaglandin profile through interference with leukocyte function and prostaglandin 15-hydroxydehydrogenase [5].

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Purified intestinal macrophages obtained at resections for colonic neoplasms were investigated for chemotaxis to leukotriene B4 (LTB4) by the Millipore filter assay and leading front technique. Possible inhibition by drugs effective in the treatment of chronic inflammatory bowel disease (sulphasalazine, Olsalazine, its active moiety 5-aminosalicylic acid (5-ASA), and the 5-ASA metabolite N-acetylated-5-ASA (ac-5-ASA)) was tested at therapeutic colonic concentrations of 0.01-10 mM. Leukotriene B4 at a dose of 10 nM was equipotent with casein (5 g litre-1) as regards chemoattraction of macrophages. Sulphasalazine, Olsalazine and 5-ASA were potent inhibitors of macrophages chemotaxis to LTB4 with IC50 values of 0.43, 0.39 and 0.24 mM, respectively. These concentrations are below the lowest concentration of 5-ASA (2 mM) in the colonic lumen during conventional sulphasalazine treatment of patients with chronic inflammatory bowel disease. The inhibition of macrophage chemotaxis by these drugs may be important for this limitation of the local inflammatory process in chronic inflammatory bowel disease, and may in part explain the beneficial effect of systemic and local treatment with sulphasalazine. Leukotriene B4 appears to be an important inflammatory mediator for the activation of macrophages in colonic inflammation.[2]

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The in vitro antioxidant capacity of sulfasalazine (SASP), its metabolites (SP, 5-ASA), and Olsalazine (OAZ), was studied by evaluating their effects on superoxide (O2-.) production. Assay systems were the xanthine-xanthine oxidase (X/XOD) reaction and phorbol myristate acetate (PMA)-activated polymorphonuclear leukocytes (PMNs), using the cytochrome c (cyt-c) reduction assay and a luminol-dependent chemiluminescence method. 5-ASA, SASP, and OAZ showed a dose-dependent scavenger effect in both O2-. generating systems, 5-ASA being the most powerful (greater than 50% of inhibition in the PMNs system and greater than 70% in the X/XOD system at 10 microM concentration). SP had an inhibitory effect only in the PMNs system but did not modify the activity of xanthine oxidase, thus excluding a scavenger action. These data suggest that the scavenger effect of 5-ASA, SASP, and OAZ may be an important mechanism of action.[3]

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Purified intestinal macrophages obtained at resections for colonic neoplasms were investigated for chemotaxis to leukotriene B4 (LTB4) by the Millipore filter assay and leading front technique. Possible inhibition by drugs effective in the treatment of chronic inflammatory bowel disease (sulphasalazine, olsalazine, its active moiety 5-aminosalicylic acid (5-ASA), and the 5-ASA metabolite N-acetylated-5-ASA (ac-5-ASA)) was tested at therapeutic colonic concentrations of 0.01-10 mM. Leukotriene B4 at a dose of 10 nM was equipotent with casein (5 g litre-1) as regards chemoattraction of macrophages. Sulphasalazine, olsalazine and 5-ASA were potent inhibitors of macrophages chemotaxis to LTB4 with IC50 values of 0.43, 0.39 and 0.24 mM, respectively. These concentrations are below the lowest concentration of 5-ASA (2 mM) in the colonic lumen during conventional sulphasalazine treatment of patients with chronic inflammatory bowel disease. The inhibition of macrophage chemotaxis by these drugs may be important for this limitation of the local inflammatory process in chronic inflammatory bowel disease, and may in part explain the beneficial effect of systemic and local treatment with sulphasalazine. Leukotriene B4 appears to be an important inflammatory mediator for the activation of macrophages in colonic inflammation.

Olsalazine was created as a means of getting mesalazine into the colon because, when taken orally, very little of the parent molecule is absorbed from the gastrointestinal tract. Azole bonds are broken down in the colon by azoreductase bacteria, releasing two molecules of mesalazine that have been shown to be therapeutically effective in treating inflammatory bowel disorders. [1] Experimental colitis induced by dextran sulphate sodium in nu/nu CD-1 mice is significantly prolonged in survival when ossalazine (50 mg/kg/day) is administered. [7] Tumor growth is inhibited by olsalazine in a rodent model of colorectal cancer. Olsalazine (25 mg/kg/day) reduces the number and volume of tumors in rats treated with 1,2-dimethylhydrazine by 58.17% and 62.67%, respectively. When olsalazine is administered, the number of apoptotic cells increases 1.7 times, and the rate of cell proliferation decreases by 42.4%. [8]

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The ability of 5-aminosalicylic acid and Olsalazine to inhibit colonic aberrant crypts and tumors was investigated in 1,2-dimethylhydrazine-treated rats. The effect of these drugs on the rates of tumor apoptosis and proliferation was studied as potential mechanisms for their action. 5-Aminosalicylic acid reduced the number of aberrant crypt foci by over one third, while olsalazine had no effect on this parameter. However, both agents effectively reduced tumor number and load, increased the rate of tumor apoptosis, and reduced the rate of tumor cell proliferation. In conclusion, 5-aminosalicylic acid and olsalazine are both ultimately effective chemopreventive agents in this model; however, only 5-aminosalicylic acid inhibited the formation of aberrant crypt foci. The inhibitory effect of these agents in tumors is related to the inhibition of proliferation and the induction of apoptosis.[8]

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Olsalazine (sodium azodisalicylate; azodisal sodium) is an anti-inflammatory agent designed to deliver its active moiety, mesalazine (5-aminosalicylic acid; mesalamine), to the colon while avoiding the adverse effects associated with the use of a sulfapyridine carrier. As a prodrug, olsalazine is an effective oral treatment for both active ulcerative colitis and for maintenance of disease remission and may possibly be of benefit in patients with Crohn's colitis. Findings from both short and long term noncomparative and comparative studies demonstrate that olsalazine 1 to 3g daily in divided doses improves clinical signs and symptoms of colitis in approximately 60 to 80% of patients with acute ulcerative colitis of mild to moderate severity. This improvement rate was similar to that obtained with sulfasalazine. Lower doses of olsalazine, usually 1g daily in divided doses, also maintained remission in patients with chronic ulcerative colitis. While Olsalazine effectively delivers mesalazine to the colon, the prodrug itself increases net luminal water secretion and accelerates gastrointestinal transit of a meal. The resulting diarrhoea (occurring in approximately 17% of patients and resulting in withdrawal from therapy in 6% of patients) is distinguishable from that associated with inflammatory bowel disease by the high water content and the absence of blood. Olsalazine-induced diarrhoea usually occurred soon after initiation of olsalazine therapy or dosage increase, was more frequent with higher doses and was usually transient. Dosage reduction, increases in frequency of dosing and concomitant administration with food reduced the severity in many patients with persistent olsalazine-induced diarrhoea. With the exception of diarrhoea, olsalazine was generally well tolerated. Fewer than 14% of patients allergic to or intolerant of sulfasalazine had similar reactions to olsalazine. Olsalazine appears to be a suitable therapy for the treatment of first attacks as well as acute exacerbation of mild to moderate acute ulcerative colitis, and for the maintenance of remission in patients with chronic ulcerative colitis. [1]

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Significant amelioration was seen on these parameters after different treatment protocols. Survival in nu/nu CD-1 mice was studied, and after 16 days a death rate of 50% was noted in the DSS group. SASP (100 mg/kg/day) and Olsalazine/OLZ (50 mg/kg/day) significantly prolonged the survival to 29 and 38 days, respectively. SASP and OLZ showed a dose-dependent effect in the range between 10 and 100 mg/kg/day, doses closely corresponding to those used in humans. Conclusions: SASP and OLZ are able to ameliorate the DSS-induced intestinal inflammation. The dose-response patterns suggested that the active therapeutic moiety for the two drugs appears to be mainly the liberated 5-ASA molecule. [7]

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The ability of 5-aminosalicylic acid and olsalazine to inhibit colonic aberrant crypts and tumors was investigated in 1,2-dimethylhydrazine-treated rats. The effect of these drugs on the rates of tumor apoptosis and proliferation was studied as potential mechanisms for their action. 5-Aminosalicylic acid reduced the number of aberrant crypt foci by over one third, while Olsalazine had no effect on this parameter. However, both agents effectively reduced tumor number and load, increased the rate of tumor apoptosis, and reduced the rate of tumor cell proliferation. In conclusion, 5-aminosalicylic acid and olsalazine are both ultimately effective chemopreventive agents in this model; however, only 5-aminosalicylic acid inhibited the formation of aberrant crypt foci. The inhibitory effect of these agents in tumors is related to the inhibition of proliferation and the induction of apoptosis [8].

The scavenger effect of SASP and Olsalazine/OAZ was tested with the spectrophotometric method because of their intense yellow color in solution that could interfere with the luminescence method. The same method was also used for SP. The scavenger effect of 5-ASA was assayed with the chemiluminescence method because of its direct chemical reduction of cyt-c. In the X/XOD system, uric acid formation was evaluated, in presence or absence of drugs, by following spectrophotometrically the production of urate at 293 nm. The drugs were dissolved in distilled water (Olsalazine/OAZ) or in KOH 0.3 M diluted in distilled water (5-ASA, SASP, SP), and pH was adjusted to 7.2. Drugs, used in the range of concentration of 10-400 ~M, were added before the xanthine oxidase and PMA addition, respectively, in the XdXOD and PMN system. Experiments were performed in triplicate on separate days, using PMNs from five different healthy subjects. [3]

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The in vitro antioxidant capacity of sulfasalazine (SASP), its metabolites (SP, 5-ASA), and Olsalazine (OAZ), was studied by evaluating their effects on superoxide (O2-.) production. Assay systems were the xanthine-xanthine oxidase (X/XOD) reaction and phorbol myristate acetate (PMA)-activated polymorphonuclear leukocytes (PMNs), using the cytochrome c (cyt-c) reduction assay and a luminol-dependent chemiluminescence method. 5-ASA, SASP, and OAZ showed a dose-dependent scavenger effect in both O2-. generating systems, 5-ASA being the most powerful (greater than 50% of inhibition in the PMNs system and greater than 70% in the X/XOD system at 10 microM concentration). SP had an inhibitory effect only in the PMNs system but did not modify the activity of xanthine oxidase, thus excluding a scavenger action. These data suggest that the scavenger effect of 5-ASA, SASP, and OAZ may be an important mechanism of action[3].

Chemotaxis [2]
Macrophages were adjusted to 2 x lo6 cells/ml (calculated using a mean of thetwo staining methods) and added to the cell compartment of modified Boydenchambers." The migration proceeded in 8 pm pore size filters''for 3 h at 37 O C in humidified air ( 5 % CO,) towards an optimalconcentration of freshly prepared LTB, (10n ~ ).Serial dilutions of test drugs were added to the cell compartments in theBoyden chambers." Results were based on analyses of five randomly selectedfields on each of two replicate filters by the leading front technique."Inhibition by the test drugs (Olsalazine) was expressed as IC,, values (drug concentrationnecessary to suppress chemotaxis by 50 %).'" 'Spontaneous' migration towardsGey's solution was subtracted before analysis of the logarithmic dose-responsecurves by interpolation.''Casein (5 g litre-')'' was included as a positive control in all experiments.

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Purified intestinal macrophages obtained at resections for colonic neoplasms were investigated for chemotaxis to leukotriene B4 (LTB4) by the Millipore filter assay and leading front technique. Possible inhibition by drugs effective in the treatment of chronic inflammatory bowel disease (sulphasalazine, olsalazine, its active moiety 5-aminosalicylic acid (5-ASA), and the 5-ASA metabolite N-acetylated-5-ASA (ac-5-ASA)) was tested at therapeutic colonic concentrations of 0.01-10 mM. Leukotriene B4 at a dose of 10 nM was equipotent with casein (5 g litre-1) as regards chemoattraction of macrophages. Sulphasalazine, olsalazine and 5-ASA were potent inhibitors of macrophages chemotaxis to LTB4 with IC50 values of 0.43, 0.39 and 0.24 mM, respectively. These concentrations are below the lowest concentration of 5-ASA (2 mM) in the colonic lumen during conventional sulphasalazine treatment of patients with chronic inflammatory bowel disease. The inhibition of macrophage chemotaxis by these drugs may be important for this limitation of the local inflammatory process in chronic inflammatory bowel disease, and may in part explain the beneficial effect of systemic and local treatment with sulphasalazine. Leukotriene B4 appears to be an important inflammatory mediator for the activation of macrophages in colonic inflammation[2].

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We investigated the action of the new aminosalicylate olsalazine (disodium azodisalicylate) on arachidonic acid metabolism in comparison with 5-aminosalicylic acid (5-ASA) and sulphasalazine (SASP) by in vitro incubation of cellular homogenates from human polymorphonuclear (PMNL) and mononuclear (MNL) leukocytes with 14C-labelled arachidonic acid. Olsalazine reduced the synthesis of leukotriene B4 (LTB4), 5-hydroxyeicosatetraenoic acid (5-HETE), 11-HETE, 12-HETE, and 15-HETE in PMNL and MNL slightly less than SASP. 5-ASA was significantly less inhibitory than olsalazine and SASP on the formation of lipoxygenase products in PMNL and on LTB4 synthesis in MNL. In contrast, in MNL the formation of 5-HETE was unaffected, and the production of 11-HETE, 12-HETE, and 15-HETE was even slightly activated by 5-ASA. Total prostaglandin synthesis was dose-dependently reduced by the aminosalicylates (SASP greater than olsalazine greater than 5-ASA), but only SASP markedly altered the prostaglandin (PG) profile, with an increase in PGE2 and PGF2 alpha at the expense of other cyclooxygenase products. It may be concluded that olsalazine resembled SASP with regard to the inhibition of the lipoxygenase but had effects intermediate between the other salicylates on cyclooxygenase. Furthermore, the alteration of the prostaglandin profile by SASP points to an overlying cofactor effect of this drug.

Primary colonic tumors induced with DMH
\n25 mg/kg/day
\nAdministered in food

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\n\nDSS was used to induce intestinal inflammation in conventional Balb/c mice and athymic nu/nu CD-1(BR) mice, and the well-documented 5-aminosalicylic acid (5-ASA) based anticolitis drugs sulphasalazine (SASP) and olsalazine (OLZ) were used to study therapeutic effects. Parameters which have been shown to reflect DSS-induced intestinal inflammation (body weight, colon length, spleen weight, diarrhoea, and rectal bleeding) were measured in the Balb/c mice.[7]\n

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\n\nInduction of colitis [7]
\nColon inflammation was induced by the administration of DSS in the drinking water. DSS with Mw 40–44 kDa and a sulphur content of 15.4–17.0% (TdB Consultancy, Uppsala, Sweden) was dissolved in ultra-pure water (< 0.05 μS/cm; Seral UP-50, Ransbach, Germany) at concentrations of 2.5% and 5.0% to a final pH 8.5. The characteristics of the DSS substance and the stability in solution have been assessed previously.7 The animals were exposed to the different DSS solutions ad libitum. The water and DSS were tested for bacterial endotoxin contamination. The water was negative (endotoxin < 0.06 EU per mL) in a Limulus Amebocyte Lysate test performed according to the United States Pharmacopoeia (USP).26 The DSS was negative in a pyrogen test in the rabbit (USP).
\n\nSeveral experimental protocols were used:
\n\n(a) An acute protocol where a high dose of DSS was used to induce a severe intestinal inflammation in Balb/c mice. Inflammation was induced with 5% DSS given in the drinking water for up to 10 days, together with treatment with SASP (see pharmacological treatment below), 100 mg/kg/day. Control animals received water only or 5% DSS only.\n
\n(b) Cyclic protocols has been used to induce intestinal inflammation with a high dose of DSS given in a cyclic manner with water periods between DSS doses to give the intestine a chance to recover. We used a cyclic protocol, using two or three cycles of 7 days of 5% DSS administration to Balb/c mice, interspersed with 7 days of plain drinking water and continuous treatment with SASP, 100 mg/kg/day for the whole experimental period. Control animals received water or 5% DSS only.\n
\n(c) Inflammatory bowel disease in humans is a chronic disease and we wanted to try to induce a stable and more chronic inflammation in the animals. We used a chronic protocol where Balb/c mice were given a lower dose of 2.5% DSS for up to 35 days, together with treatment with SASP at a dose of 100 mg/kg/day. Control animals were given water or 2.5% DSS only.\n
\n(d) Since the active moiety in SASP is thought to be 5-ASA, we wanted to compare SASP, which has one 5-ASA molecule with Olsalazine/OLZ, which has two 5-ASA molecules. Therefore we calculated the doses on an equimolar basis. Thus we used a comparison chronic protocol whereby nu/nu CD-1 mice were given oral 2.5% DSS for 38 days and treatment with nearly equimolar doses of SASP and OLZ with respect to the 5-ASA metabolite, in dosages of 100 and 50 mg/kg/day. Control animals were given water or 2.5% DSS only.\n
\n(e) In addition, we wanted to compare SASP with Olsalazine/OLZ in a dose dependent manner in the chronic situation, which is more relevant to the human disease. Thus we designed a dose–response study in nu/nu CD-1 mice given oral 2.5% DSS for 38 days and treatment with SASP or OLZ in doses of 10, 30, 50 and 100 mg/kg/day. Control animals were given water or 2.5% DSS only.\n

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\nPharmacological treatment [7]
\nSASP and Olsalazine/OLZ were synthesized. The pharmacological treatment was given orally by combining the drug and DSS in the drinking water. The treatment was started on the first day of DSS-exposure and continued throughout the observation period. The daily water intake was measured prior to the start of the experiments, and the drug concentration was adjusted to obtain the intended daily dosage with ad␣libitum access to the animals. There was no difference in fluid intake between any of the combinations tested and no clinical effects of the DSS, given alone or together with the drug treatment were observed over the first 3 days.\n

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\n\nTreatment Groups. [8]
\nRats were randomized to a control group (N 5 12) or groups treated with either Olsalazine (N 5 10) or 5-ASA (N 5 10). 5-ASA was suspended in 1% methyl cellulose and olsalazine dissolved in water. Control animals received 1% methyl cellulose alone. Treatment was administered twice daily in divided doses by orogastric gavage, after briefly anaesthetizing with CO2. Treatment commenced on the day after the first dose of DMH and continued for three weeks, with a 24-hr break on the day of the second DMH dose.\n

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\n\nTreatment Groups. [8]
\nRats were randomized to the control group (N 5 12) or to groups treated with either Olsalazine (N 5 10) or 5-ASA (N 5 9). Drugs were administered in the food. The amount eaten was monitored, and the mixture adjusted to ensure delivery of the required daily dose. Treatment commenced on the day after the first dose of DMH and continued for 23 weeks.\n\n

Absorption
After oral administration, olsalazine has limited systemic bioavailability, with absorption rates less than 5% of the oral dose. Based on oral and intravenous administration studies, the absorption rate of a single oral dose of 1 gram of olsalazine is approximately 2.4%. Peak serum concentrations of olsalazine occur approximately 1 hour later, and even with a single 1-gram dose, concentrations are low (e.g., 1.6 to 6.2 µmol/L). In patients taking 1 gram of olsalazine daily for 2 to 4 years, plasma olsalazine-S concentrations stabilized at 3.3 to 12.4 µmol/L. Olsalazine-S accumulates to steady state within 2 to 3 weeks. Mesalazine serum concentrations are detectable 4 to 8 hours later. Peak concentrations of mesalazine following oral administration of 1 gram of olsalazine are low (i.e., 0 to 4.3 µmol/L).
Excretion
Olsalazine and its metabolites are excreted in the urine. The overall recovery rate of orally administered 14C-labeled olsalazine in animals and humans is 90% to 97%. Approximately 20% of the total mesalazine is recovered in urine. Of the total mesalazine recovered in urine, over 90% is N-acetyl-5-aminosalicylic acid (N-acetyl-5-ASA). Only trace amounts of mesalazine are detected in urine. The remaining mesalazine is partially acetylated and excreted in feces. The concentration of mesalazine in the colon after administration of olsalazine was measured by fecal dialysis to be 18 to 49 mmol/L. The urinary recovery rate of olsalazine is less than 1%. Of the oral dose (0.25 to 2 g), less than 5% is recovered unchanged in feces. However, when the total intestinal transit time is reduced by approximately 50%, over 50% of the oral dose is excreted in feces as unmetabolized olsalazine.
Volume of Distribution
The steady-state volume of distribution measured in healthy volunteers is approximately 5 liters.

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Metabolites
Olsalazine releases its active ingredient, mesalazine, through lysis by colonic bacteria. Mesalazine can be acetylated in colonic epithelial cells to N-acetyl-5-aminosalicylic acid (N-acetyl-5-ASA, Ac-5-ASA); however, the degree of acetylation depends on the transport time. Approximately 0.1% of orally administered olsalazine is metabolized in the liver to olsalazine-O-sulfate (olsalazine-S).

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Biological Half-Life
Olsalazine has a short serum half-life of approximately 0.9 hours. Olsalazine extended-release tablets (Olsalazine-S) have a half-life of 7 days due to slow dissociation from the protein binding site.

Effects During Pregnancy and Lactation
◉ Overview of Use During Lactation
Limited data suggest that olsalazine is rarely excreted into breast milk. However, olsalazine is a prodrug of mesalazine. High concentrations of the mesalazine metabolite N-acetyl-5-aminosalicylic acid (N-acetyl-5-ASA) are present in breast milk, but its effects on breastfed infants are unclear. Although the incidence is low, there have been a few reports of infants experiencing diarrhea after taking mesalazine. Most experts consider the use of mesalazine derivatives during lactation to be acceptable. If the mother needs to take olsalazine, this is not a reason to stop breastfeeding, but the breastfed infant should be closely monitored for diarrhea while the mother is taking olsalazine.
◉ Effects on Breastfed Infants
An infant was breastfed while the mother was taking olsalazine to treat Crohn's disease. The infant did not experience rash, wheezing, vomiting, or diarrhea after 2 and 3 weeks of treatment.
Mesalazine, the active metabolite of olsalazine, may have been the cause of diarrhea in a 6-week-old infant who experienced four recurrent episodes of diarrhea after four subsequent doses of olsalazine while the mother was breastfeeding.
In a prospective telephone follow-up study, eight breastfeeding mothers reported taking mesalazine (dosage and route of administration not specified). One mother reported diarrhea in her infant. No other adverse events were reported by the mothers.
A case-control study compared infants born to mothers taking mesalazine (n = 117; mean dose, 2065 mg daily), olsalazine (n = 2), or sulfasalazine (n = 2) with infants born to a mother-matched control group (n = 121). Control group mothers did not receive any treatment known to be harmful to breastfed infants. The mean time of breastfeeding exposure to mesalazine was 5.3 months (range: 3 days to 24 months). Infants were breastfed for a mean of approximately 7.4 months and were followed up at a mean of approximately 22 months of age. There was no difference in the frequency or characteristics of maternally reported adverse events between infants in the exposed and control groups.
◉ Effects on breastfeeding and breast milk
As of the revision date, no relevant published information was found.

[1]. Drugs. 1991 Apr;41(4):647-64.

[2]. Aliment Pharmacol Ther. 1988 Jun;2(3):203-11.

[3]. Dig Dis Sci. 1991 Feb;36(2):174-8.

[4]. Dig Dis Sci. 1987 Jun;32(6):577-82.

[5]. Dig Dis Sci. 1985 Dec;30(12):1161-5.

[6]. Acta Med Scand. 1979;206(6):451-7.

[7]. Aliment Pharmacol Ther. 1998 Sep;12(9):925-34.

[8]. Dig Dis Sci. 2000 Aug;45(8):1578-84.

Orsalazine is an azobenzene compound composed of two 4-aminosalicylic acid molecules linked by an azo bond. It is a prodrug of the anti-inflammatory drug mesalazine, used as a disodium salt for the treatment of inflammatory bowel disease. It is both a prodrug and a nonsteroidal anti-inflammatory drug (NSAID). It is a dicarboxylic acid belonging to the azobenzene class of compounds. Functionally, it is related to salicylic acid. It is the conjugate acid of olsalazine (2-).
Osalazine is an aminosalicylic acid salt.
See also: Orsalazine (note moved to).

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Osalazine sodium is an organosalate salt, the disodium salt of 3,3'-azobis(6-hydroxybenzoic acid) (olsalazine). It is effective in treating inflammatory bowel disease and ulcerative colitis. The mechanism of action is not fully understood, but it appears to act primarily through local administration. It is a NSAID and a prodrug. It contains olsalazine (2-).
See also: Orsalazine sodium (note moved to). Osalazine (sodium azobisalicylate) is an anti-inflammatory drug designed to deliver its active ingredient, mesalazine (5-aminosalicylic acid), to the colon while avoiding the adverse effects associated with sulfasalazine carriers. As a prodrug, olsalazine is effective orally in treating active ulcerative colitis and maintaining disease remission, and may be beneficial for patients with Crohn's disease. Short-term and long-term uncontrolled and controlled studies have shown that daily doses of 1 to 3 grams of olsalazine, divided into several doses, improve clinical signs and symptoms in approximately 60% to 80% of patients with mild to moderate acute ulcerative colitis. This improvement rate is similar to that of sulfasalazine. Lower doses of olsalazine (usually 1 gram daily divided into several doses) can also maintain remission in patients with chronic ulcerative colitis. Osalazine effectively delivers mesalazine to the colon, and its prodrug itself increases intestinal clot regurgitation and accelerates gastrointestinal transit of food. The resulting diarrhea (occurring in about 17% of patients, of whom 6% discontinued treatment as a result) is different from diarrhea associated with inflammatory bowel disease, characterized by high water content and no bloody stools. Osalazine-induced diarrhea usually occurs shortly after the start of salazine treatment or after increasing the dose, with higher doses resulting in a higher incidence of diarrhea, and is usually transient. For patients with persistent salazine-induced diarrhea, reducing the dose, increasing the frequency of administration, and taking it with food can reduce the severity of diarrhea. Apart from diarrhea, salazine is generally well tolerated. Less than 14% of patients who are allergic to or intolerant to sulfasalazine have a similar response to salazine. Osalazine appears to be suitable for the treatment of first exacerbations and acute exacerbations of mild to moderate acute ulcerative colitis, as well as for maintaining remission in patients with chronic ulcerative colitis. [1]

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The chemotaxis of purified intestinal macrophages to leukotriene B4 (LTB4) in colon tumor resection specimens was investigated using the Millipore filtration method and cutting-edge technology. The inhibitory effects of drugs used to treat chronic inflammatory bowel disease (CIG) (sulfasalazine, olsalazine, its active ingredient 5-aminosalicylic acid (5-ASA), and the 5-ASA metabolite N-acetylated-5-ASA (ac-5-ASA)) on LTB4 chemotaxis were tested at therapeutic concentrations ranging from 0.01 to 10 mM. The results showed that 10 nM of leukotriene B4 had similar potency to casein (5 g/L) in macrophage chemotaxis. Sulfasalazine, olsalazine, and 5-aminosalicylic acid (5-ASA) were potent inhibitors of macrophage chemotaxis towards LTB4, with IC50 values of 0.43, 0.39, and 0.24 mM, respectively. These concentrations were lower than the lowest intracolonic concentration of 5-ASA (2 mM) observed in CIG patients receiving standard sulfasalazine treatment. The inhibition of macrophage chemotaxis by these drugs may be crucial for limiting local inflammatory processes in chronic inflammatory bowel disease and may partially explain the benefits of systemic and local treatment with sulfasalazine. Leukotriene B4 appears to be an important inflammatory mediator of macrophage activation in colonic inflammation. [2]

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This study investigated the in vitro antioxidant capacity of sulfasalazine (SASP), its metabolites (SP, 5-aminosalicylic acid, 5-ASA), and olsalazine (OAZ) by evaluating their effects on superoxide (O2-) generation. The detection systems included xanthine-xanthine oxidase (X/XOD) reaction and phorbol myristate (PMA) activated polymorphonuclear leukocyte (PMN) assay, which were performed using cytochrome c (cyt-c) reduction and luminol-dependent chemiluminescence. 5-ASA, SASP, and OAZ all showed dose-dependent O2- scavenging effects. In the production system, 5-ASA showed the strongest inhibitory effect (inhibition rate exceeding 50% in the PMN system and exceeding 70% in the X/XOD system at a concentration of 10 μM). SP only showed inhibitory effect in the PMN system, but did not change the activity of xanthine oxidase, thus ruling out its scavenging effect. These data suggest that the scavenging effects of 5-ASA, SASP and OAZ may be important mechanisms of action. [3]

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This study investigated the possible effects of sulfasalazine, 5-aminosalicylic acid and acetyl-5-aminosalicylic acid on the release and metabolism of endogenous arachidonic acid in human polymorphonuclear leukocytes (PMN). We used a novel in vitro detection method to incorporate [1-14C]arachidonic acid into purified peripheral blood PMN until steady state was reached (5 hours). Before activation with calcium ion carrier A23187, the test drug was pre-incubated, and the released eicosate was separated by extraction and thin-layer chromatography (TLC) and quantified by autoradiography and laser densitography. The median drug concentrations required for sulfasalazine and 5-aminosalicylic acid to inhibit 50% release of leukotrienes B4 and 5-hydroxyeicosatetraenoic acid (5-HETE) were 4-5 mM (range 1-9 mM). Acetylated derivatives of 5-aminosalicylic acid were ineffective. Current data suggest that inhibition of arachidonic acid lipoxygenation may be an important role of sulfasalazine and its active metabolite 5-aminosalicylic acid. Interference with lipoxygenase activity, rather than inhibiting intracellular phospholipid release of arachidonic acid as steroids do, appears to be its mechanism of action. [4] The effects of sulfasalazine and its derivatives on the synthesis of arachidonic acid metabolites in human colonic mucosa have been studied. Sulfasalazine inhibits the synthesis of lipoxygenase products. Sulfasalazine and sulfapyridine also inhibit the synthesis of thromboxane B2, while promoting the synthesis of prostaglandin F2α or PGE2. Inhibition of lipoxygenase product synthesis and regulation of the cyclooxygenase product spectrum can alleviate inflammation in ulcerative colitis and enhance the resistance of the mucosa to injury. [5]

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Sulfasalazine and its active ingredients 5-aminosalicylic acid (5-ASA) and sulfapyridine (SP) are potent modulators of inflammatory responses, but their mechanisms of action are slightly different. We studied the effects of these compounds on normal human polymorphonuclear leukocytes in vitro and found that they inhibited different stages of phagocytosis, such as migration (sulfasalazine and SP), superoxide generation (sulfasalazine and SP), myeloperoxidase-mediated iodination, and cytotoxicity (5-ASA and SP). Therefore, it has been shown that sulfasalazine is not only a delivery carrier of its active ingredients in the colon, but its therapeutic effect on ulcerative colitis and other inflammatory responses is the result of the combined action of the three compounds. [6]

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Different treatment regimens significantly improved these indicators. Researchers studied the survival of CD-1 in nude mice and found that the mortality rate in the DSS group reached 50% after 16 days. SASP (100 mg/kg/day) and OLZ (50 mg/kg/day) significantly prolonged the survival of mice to 29 days and 38 days, respectively. SASP and OLZ showed dose-dependent effects in the dose range of 10 to 100 mg/kg/day, which is very close to the dose used in humans. Conclusion: SASP and OLZ can improve DSS-induced intestinal inflammation. The dose-response pattern suggests that the active therapeutic components of these two drugs appear to be mainly the released 5-aminosalicylic acid (5-ASA) molecules. [7]

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The ability of 5-aminosalicylic acid and olsalazine to inhibit abnormal colonic crypts and tumors was studied in rats treated with 1,2-dimethylhydrazine. The effects of these drugs on tumor cell apoptosis and proliferation rate were investigated as potential mechanisms of action. 5-Aminosalicylic acid reduced the number of abnormal crypt foci by more than one-third, while olsalazine had no effect on this parameter. However, both drugs effectively reduced the number and burden of tumors, increased the tumor cell apoptosis rate, and reduced the tumor cell proliferation rate. In summary, 5-aminosalicylic acid and olsalazine were the ultimate effective chemopreventive agents in this model; however, only 5-aminosalicylic acid inhibited the formation of abnormal crypt foci. The inhibitory effects of these drugs on tumors are related to the inhibition of proliferation and the induction of apoptosis. [8]

C14H10N2O6

302.239

302.054

C, 55.64; H, 3.34; N, 9.27; O, 31.76

15722-48-2

Olsalazine Disodium;6054-98-4

22419

Light yellow to yellow solid powder

1.55g/cm3

653.233ºC at 760 mmHg

348.863ºC

0mmHg at 25°C

1.678

2.909

4

8

4

22

415

0

QQBDLJCYGRGAKP-UHFFFAOYSA-N

InChI=1S/C14H10N2O6/c17-11-3-1-7(5-9(11)13(19)20)15-16-8-2-4-12(18)10(6-8)14(21)22/h1-6,17-18H,(H,19,20)(H,21,22)

5-[(3-carboxy-4-hydroxyphenyl)diazenyl]-2-hydroxybenzoic acid

Salicylic acid; Dipentium; 15722-48-2; Olsalazina; Olsalazinum; Olsalazine

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: This product requires protection from light (avoid light exposure) during transportation and storage.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)