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]

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].

Primary colonic tumors induced with DMH
25 mg/kg/day
Administered in food

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DSS 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]

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Induction of colitis [7]
Colon 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).
Several experimental protocols were used:
(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.
(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.
(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.
(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.
(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.

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Pharmacological treatment [7]
SASP 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.

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Treatment Groups. [8]
Rats 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.

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Treatment Groups. [8]
Rats 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.

Absorption
After oral administration, olsalazine has limited systemic bioavailability, with less than 5% of the oral dose being absorbed. Based on oral and intravenous dosing studies, approximately 2.4% of a single 1 g oral dose is absorbed. Maximum serum concentrations of olsalazine appear after approximately one hour and, even after a 1 g single dose, are low (e.g., 1.6 to 6.2 µmol/L). Patients on daily doses of 1 g olsalazine for two to four years show a stable plasma concentration of olsalazine-S (3.3 to 12.4 µmol/L). Olsalazine-S accumulates to a steady state within two to three weeks. Serum concentrations of mesalamine are detected after four to eight hours. The peak levels of mesalamine after an oral dose of 1 g olsalazine are low (i.e., 0 to 4.3 µmol/L).

Route of Elimination
Olsalazine and its metabolites are excreted in the urine. Total recovery of oral 14C-labeled olsalazine in animals and humans ranges from 90 to 97%. Approximately 20% of the total mesalamine is recovered in the urine. Of the total mesalamine found in the urine, more than 90% is N-acetyl-5-ASA. Only small amounts of mesalamine are detected in the urine. The remaining mesalamine is partially acetylated and excreted in the feces. From fecal dialysis, the concentration of mesalamine in the colon following olsalazine has been calculated to be 18 to 49 mmol/L. The urinary recovery of olsalazine is below 1%. Less than 5% of an oral dose (0.25 to 2g) was recovered unchanged in the feces; however, more than 50% of the oral dose was excreted in feces as unchanged olsalazine when the whole gut transit time was decreased by approximately 50%.

Volume of Distribution
The steady-state volume of distribution determined in healthy volunteers is approximately 5L.

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Metabolism / Metabolites
Olsalazine is cleaved by colonic bacteria to release its active ingredient, mesalamine. Mesalamine can undergo acetylation to form N-acetyl-5-aminosalicylic acid (N-acetyl-5-ASA, Ac-5-ASA) by the colonic epithelium; however, the extent of acetylation depends on transit time. Approximately 0.1% of an oral dose of olsalazine is metabolized in the liver to olsalazine-O-sulfate (olsalazine-S).

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Biological Half-Life
Olsalazine has a very short serum half-life, approximately 0.9 hours. Olsalazine-S has a half-life of seven days due to slow dissociation from the protein binding site.

Effects During Pregnancy and Lactation
◉ Summary of Use during Lactation
Limited data indicate that olsalazine is poorly excreted into breastmilk. However, olsalazine is a mesalamine prodrug. Rather high levels of the mesalamine metabolite N-acetyl-5-ASA appear in breastmilk and its effects on breastfed infants are unknown. A few cases of diarrhea have been reported in infants exposed to mesalamine, although the rate is not high. Most experts consider mesalamine derivatives to be acceptable during breastfeeding. If olsalazine is required by the mother, it is not a reason to discontinue breastfeeding, but carefully observe breastfed infants for diarrhea during maternal use of olsalazine.
◉ Effects in Breastfed Infants
One infant was breastfed during maternal therapy with olsalazine for Crohn's disease. After 2 and 3 weeks of therapy, no rash, wheezing, vomiting or diarrhea were noted in the infant.
The active metabolite of olsalazine, mesalamine, was probably responsible for diarrhea in a 6-week-old whose diarrhea recurred 4 times after rechallenging the mother 4 times during breastfeeding.
In a prospective telephone follow-up study, 8 nursing mothers reported taking mesalamine (dosage and route unspecified). One mother reported diarrhea in her infant. No other adverse reactions were reported in the infants by their mothers.
A case-control study compared the infants of mothers taking mesalamine (n = 117; average dose, 2065 mg daily), olsalazine (n = 2) or sulfasalazine (n = 2) to infants of matched control mothers (n = 121) who were exposed to no treatment known to be harmful to a breastfed infant. Infants were exposed to mesalamine through milk for a mean of 5.3 months (range: 3 days-24 months). Infants were breastfed for an average of about 7.4 months and were followed up at an average age of about 22 months. No difference in the frequency or characteristics of maternally reported adverse events were found between exposed and control infants.
◉ Effects on Lactation and Breastmilk
Relevant published information was not found as of the revision date.

[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.

Olsalazine sodium is an organic sodium salt that is the disodium salt of 3,3'-azobis(6-hydroxybenzoic acid) (olsalazine). Effective in the treatment of inflammatory bowel disease and ulcerative colitis. Mechanism of action unknown, but appears to be topical It has a role as a non-steroidal anti-inflammatory drug and a prodrug. It contains an olsalazine(2-).
See also: Olsalazine Sodium (annotation moved to).

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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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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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The possible effect of sulfasalazine, 5-aminosalicylic acid, and acetyl-5-aminosalicylic acid on endogenous arachidonic acid release and metabolism was studied in human polymorphonuclear leukocytes (PMNs). A new in vitro assay was used by which [1-14C]arachidonic acid is incorporated by purified peripheral PMNs until steady state was obtained (5 hr). After preincubation with the test drugs prior to activation with calcium ionophore A23187, the released eicosanoids were isolated by extraction and thin-layer chromatography (TLC) and quantitated by autoradiography and laser densitometry. Median drug concentrations needed for 50% inhibition of leukotriene B4 and 5-hydroxyeicosatetraenoic acid (5-HETE) release was 4-5 mM (range 1-9 mM) for both sulfasalazine and 5-aminosalicylic acid. The acetylated derivative of 5-aminosalicylic acid was ineffective. The present data suggest that inhibition of arachidonic acid lipoxygenation may be an essential action of sulfasalazine and its active metabolite, 5-aminosalicylic acid. Interference with lipoxygenase enzymes, rather than a steroid-like inhibition of arachidonic acid release from intracellular phospholipids, seems to be the mode of action. [4]

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The effects of sulfasalazine and its moieties on synthesis of individual products of arachidonic acid metabolism by human colonic mucosa have been investigated. Sulfasalazine inhibited synthesis of the lipoxygenase products. Sulfasalazine and sulfapyridine also inhibited synthesis of thromboxane B2 while enhancing synthesis of prostaglandin (PG) F2 alpha or PGE2, respectively. Inhibition of synthesis of lipoxygenase products and modulation of the profile of cyclooxygenase products could reduce inflammation and enhance mucosal resistance to damage in ulcerative colitis.[5]

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Sulfasalazine and its active components, 5-aminosalicylic acid (5-ASA) and sulfapyridine (SP), are potent modulators of inflammatory reactions but with somewhat different modes of action. Investigating the effect of these compounds on normal human polymorphonuclear leukocytes in vitro, we show inhibition of different stages in the phagocytic process, such as migration (sulfasalazine and SP), superoxide production (sulfasalazine and SP), myeloperoxidase-mediated iodination and cytotoxicity (5-ASA and SP). It is thus suggested that sulfasalazine is not just a vehicle for delivering its active components in the colon, but that its therapeutic effect is ulcerative colitis and other inflammatory reactions is a result of the concurrent action of the three compounds.[6]

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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 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]

C14H8N2NA2O6

346.2

346.017

C, 48.57; H, 2.33; N, 8.09; Na, 13.28; O, 27.73

6054-98-4

Olsalazine; 15722-48-2

135413505

Light yellow to yellow solid powder

557.9ºC at 760 mmHg

240ºC

291.2ºC

0.24

2

8

4

24

415

0

[Na+].[Na+].[O-]C1C([H])=C([H])C(=C([H])C=1C(=O)O[H])/N=N/C1C([H])=C([H])C(=C(C(=O)O[H])C=1[H])[O-]

ZJEFYLVGGFISGT-UHFFFAOYSA-L

InChI=1S/C14H10N2O6.2Na/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);;/q;2*+1/p-2

disodium;2-carboxy-4-[(3-carboxy-4-oxidophenyl)diazenyl]phenolate

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment (e.g. under nitrogen), avoid exposure to moisture and light.

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

Solubility in Formulation 1: 15 mg/mL (43.33 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with sonication.

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