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Disposition of 5-aminosalicylic acid from 5-aminosalicylic acid-delivering drugs during accelerated intestinal transit in healthy volunteers.

In eight healthy volunteers accelerated intestinal transit time was induced with bisacodyl, and urinary and faecal excretion of sulphasalazine, olsalazine, 5-aminosalicylic acid (5-ASA), and acetyl-5-ASA was studied after a single oral dose of 3.3 mmol sulphasalazine, olsalazine, Pentasa, and Salofalk and 2.6 mmol of Asacol. The faecal and urinary excretion of acetyl-5-ASA was lowest after intake of sulphasalazine and olsalazine and highest after intake of Pentasa and Salofalk. The figures for Asacol were intermediate. This indicates insufficient release of 5-ASA from sulphasalazine and olsalazine. When the results of this study are compared with those of a previous study without accelerated transit time, the disposition of 5-ASA from all the 5-ASA-delivering drugs is influenced unfavourably by an accelerated gut transit but most pronounced in the case of sulphasalazine, olsalazine, and Asacol. The impaired release from the azo compounds sulphasalazine and olsalazine is a result of far less complete splitting of the diazo bond.

Adult↗

New metabolites of the drug 5-aminosalicylic acid. II. N-formyl-5-aminosalicylic acid.

1. A new metabolite of the drug 5-aminosalicylic acid (5-ASA) has been found in urine from pigs and in plasma of humans. The metabolite has been isolated from pig urine using an XAD-2 column and purified using preparative h.p.l.c. 2. The metabolite has been identified as N-formyl-5-ASA (5-formamidosalicylic acid) using 1H- and 13C-n.m.r. spectrometry and mass spectroscopy and the structure was confirmed by chemical synthesis. 3. N-Formyl-5-ASA is stable in human plasma and in potassium phosphate buffers between pH 3.0 and 9.0. It is hydrolysed below pH 3.0. 4. N-Formyl-5-ASA was readily formed in rat liver homogenate when 5-ASA and N-formyl-L-kynurenine were added. Thus N-formyl-5-ASA might be formed by the actions of formamidase in vivo. 5. N-Formyl-5-ASA has been found in human plasma from healthy volunteers dosed i.v. with 5-ASA (250 mg). N-beta-D-glucopyranosyl-5-ASA, N-acetyl-5-ASA and N-formyl-5-ASA were quantified in human plasma using a h.p.l.c. assay.

Aminosalicylic Acids↗

Disposition of 5-aminosalicylic acid by 5-aminosalicylic acid-delivering compounds.

Time-related urinary excretion and faecal excretion of 5-ASA and acetyl-5-ASA were measured in eight healthy volunteers after a single oral dose of the azo compounds sulphasalazine and olsalazine, the slow release compounds Pentasa, Asacol and Salofalk, and plain 5-ASA. After ingestion of both azo compounds and slow-release compounds, urinary excretion of 5-ASA was markedly delayed and reduced, and faecal excretion was enhanced. At all points of time, there was a significant, but not very marked difference in urinary excretion of 5-ASA after ingestion of the azo compounds and the slow-release compounds, in favour of the azo compounds. A significantly larger proportion of the ingested 5-ASA, moreover, was excreted in faeces after the intake of azo compounds as compared with slow-release compounds.

Adult↗

Stability of 5-aminosalicylic acid and its metabolites in plasma at -20 degrees C. Formation of N-beta-D-glucopyranosyl-5-aminosalicylic acid.

The stability of 5-aminosalicylic acid and its metabolites has been investigated when stored frozen. N-beta-D-Glucopyranosyl-5-aminosalicylic acid was formed in considerable amounts concomitant with a decrease in 5-aminosalicylic acid in plasma samples spiked with 5-aminosalicylic acid as well as in standard solutions of 5-aminosalicylic acid buffered with potassium phosphate between pH 5.5 and pH 8.0 with 4.0 mM glucose added and stored at -20 degrees C. Thus N-beta-D-glucopyranosyl-5-aminosalicylic acid might not, as previously described, be a metabolite of 5-aminosalicylic acid but an artifact formed during storage of plasma samples. The N-glucoside formed could be quantitatively degraded to 5-aminosalicylic acid and glucose by adding 0.2 M potassium phosphate buffer pH 3.0 to the sample prior to the analysis. The metabolites of 5-aminosalicylic acid (N-formyl-5-aminosalicylic acid, N-acetyl-5-aminosalicylic acid and N-butyryl-5-aminosalicylic acid) were found to be stable in plasma stored at -20 degrees C for at least eight months.

Aminosalicylic Acids↗

New metabolites of the drug 5-aminosalicylic acid. I: N-beta-D-glucopyranosyl-5-aminosalicylic acid.

1. A new unstable metabolite of 5-aminosalicylic acid (5-ASA) was found in plasma from healthy volunteers dosed with 5-ASA i.v. 2. The metabolite was prepared by incubation of 5-ASA with rat liver homogenate, and isolated using preparative h.p.l.c. 3. The metabolite was identified as N-beta-D-glucopyranosyl-5-aminosalicylic acid by n.m.r. spectroscopy and by FAB mass spectrometry. 4. N-beta-D-Glucopyranosyl-5-ASA was formed non-enzymically from 5-ASA and glucose in phosphate buffer pH 7.4, and was unstable under weakly acidic conditions, decomposition increasing with temperature, i.e. decomposition was complete after 30 min at pH 5.0 and 23 degrees C.

Adult↗

Synthesis and properties of dextran-5-aminosalicylic acid ester as a potential colon-specific prodrug of 5-aminosalicylic acid.

Dextran-5-aminosalicylic acid ester (dextran-5-ASA) was synthesized as a colon-specific prodrug of 5-aminosalicylic acid (5-ASA) which is active against inflammatory bowel diseases. Chemical stability of dextran-5-ASA in the bath of pH 1.2 or 6.8 was investigated at 37 degrees C for 6 hrs, and 5-ASA was not released on such conditions. Depolymerization (%) of dextran-5-ASA by dextranase with the degree of substitution (DS) of 18, 23, or 30 was 92, 62 or 45 in 8 hrs respectively, but was not affected by the MW of dextran (9,000, 40,600, 80,200 or 580,000). Distribution of 5-ASA in dextran, determined by gel filtration chromatography, appeared to be relatively uniform. Incubation of dextran-5-ASA (DS 18) in cecal contents of rats released 20% (28 g) and 35% (49 g) of 5-ASA in 8 hrs and 24 hrs, respectively, but no 5-ASA was liberated from small intestinal contents.

Aminosalicylic Acids↗

Clinical evidence supporting the radical scavenger mechanism of 5-aminosalicylic acid.

5-Aminosalicylic acid, the therapeutically active metabolite of sulfasalazine, was exposed to oxygen-derived free radicals produced by the Fenton reaction in vitro, and several metabolites were detected and characterized by high performance liquid chromatography and ultraviolet spectrophotometry. The majority of these metabolites were present in methanolic extracts of feces samples from sulfasalazine-treated patients with inflammatory bowel disease but not in rheumatoid arthritis patients with normal bowel function. The presence of these metabolites, which have not been demonstrated in vivo before, provides evidence of an interaction between 5-aminosalicylic acid and oxygen-derived free radicals in sulfasalazine-treated patients with inflammatory bowel disease. Since the concentration of lipid peroxides, which is dependent on the release of oxygen-derived free radicals, was significantly increased in pretreatment rectal biopsies of the patients, and further was normalized concomitantly with a significant improvement in disease activity over the 5-wk treatment period, an important role of the radical scavenger mechanism of 5-aminosalicylic acid in sulfasalazine therapy of chronic inflammatory bowel disease is strongly suggested.

Adult↗

Oral 5-aminosalicylic acid for maintaining remission in ulcerative colitis.

OBJECTIVES: To assess the efficacy, dose-responsiveness and safety of the newer release formulations of 5-aminosalicylic acid (5-ASA) compared to placebo or sulfasalazine (SASP) in the maintenance of remission in ulcerative colitis. SEARCH STRATEGY: A computer-assisted literature search for relevant studies (1981-1998) was performed using MEDLINE, BIOS, the Cochrane Controlled Trials Register, the Inflammatory Bowel Disease Trials Register, and Science Citation Index, followed by a manual search of reference lists from previously retrieved articles, review articles, symposia proceedings, and abstracts from major gastrointestinal conferences. SELECTION CRITERIA: Studies were accepted for analysis if they were prospective, randomized, double-blinded, and placebo- or SASP-controlled clinical trials of parallel design with treatment duration of at least six months. DATA COLLECTION AND ANALYSIS: Based on an intention to treat principle, the primary outcome was the failure to maintain clinical or endoscopic remission. Secondary outcomes were the number of patients experiencing adverse events, the number of patients withdrawn due to adverse events, and exclusions or withdrawals after entry into the study (not due to relapse). All data were analyzed using the Peto odds ratio and corresponding 95% confidence intervals (CI). MAIN RESULTS: The Peto odds ratio for the failure to maintain clinical or endoscopic remission (withdrawals and relapses) for 5-ASA versus placebo was 0. 47 (95% CI, 0.36 to 0.62) with an NNT of 6. These values were also calculated for the trials in which SASP and 5-ASA were compared, revealing an odds ratio of 1.29 (95% CI, 1.05 to 1.57), with a negative NNT value (-19), suggesting a higher degree of therapeutic effectiveness for SASP. SASP and 5-ASA had similar adverse event profiles, with odds ratios of 1.16(0.62 to 2.16), and 1.31(0.86 to 1.99), respectively. The NNH values were determined to be 171 and 78 respectively. REVIEWER'S CONCLUSIONS: The newer 5-ASA preparations were superior to placebo in maintenance therapy. However, the newer preparations had a statistically significant therapeutic inferiority relative to SASP.

Administration, Oral↗

Competitive relationship between protocatechuic acid and p-aminosalicylic acid for a cellular transport mechanism.

Hubbard, Jerry S. (Oklahoma State University, Stillwater), and Norman N. Durham. Competitive relationship between protocatechuic acid and p-aminosalicylic acid for a cellular transport mechanism. J. Bacteriol. 82:361-369. 1961.-The oxidation of protocatechuic acid by a Flavobacterium is inhibited by p-aminosalicyclic acid regardless of whether the organism is grown on protocatechuic acid or sequentially induced to protocatechuic acid by growth on p-aminobenzoic acid. Depletion of the substrate from the medium by the cell suspension is dependent, within defined limits, on the inhibitor to substrate ratio, and the inhibition can be overcome by addition of excess substrate. However, this competitive effect is not observed in high inhibitor to substrate ratios. p-Aminosalicylic acid did not affect the rate or extent of oxidation, carbon dioxide evolution, or formation of beta-ketoadipic acid during degradation of protocatechuic acid by cell extracts. The results suggest that p-aminosalicylic acid antagonizes the oxidation of protocatechuic acid by the cell suspension by competing with the substrate for a specific transport mechanism, thereby regulating the entry and internal accumulation of the substrate. The lack of a competitive effect in high inhibitor to substrate ratios could be interpreted as an indication that the mechanism for accumulating the substrate may consist of more than one active transport system.

4-Aminobenzoic Acid↗

Oral 5-aminosalicylic acid for inducing remission in ulcerative colitis.

OBJECTIVES: To assess the efficacy, dose-responsiveness and safety of the newer release formulations of 5-aminosalicylic acid (5-ASA) compared to placebo or sulfasalazine (SASP) for the induction of remission in active ulcerative colitis. SEARCH STRATEGY: A computer-assisted literature search for relevant studies (1981-1998) was performed using MEDLINE, BIOS, the Cochrane Controlled Trials Register and the Science Citation Index, followed by a manual search of reference lists from previously retrieved articles, review articles, symposia proceedings, and abstracts from major gastrointestinal conferences. SELECTION CRITERIA: Studies were accepted for analysis if they were randomized, double-blinded, and controlled clinical trials of parallel design, with treatment durations of a minimum of four weeks. DATA COLLECTION AND ANALYSIS: Based on an intention to treat principle, the outcomes of interest in the treatment of active disease were the failure to induce global/clinical remission, global/clinical improvement, endoscopic remission, or endoscopic improvement. MAIN RESULTS: 5-ASA was superior to placebo with regard to all measured outcome variables. For the failure to induce global/clinical improvement or remission, the pooled Peto odds ratio was 0.51 (95% CI, 0.35 to 0.76). A dose-response trend for 5-ASA was also observed. When 5-ASA was compared to SASP, the pooled Peto odds ratio was 0.87 (CI, 0.63 to 1.21) for the failure to induce global/clinical improvement or remission, and 0.66 (CI, 0.42 to 1.04) for the failure to induce endoscopic improvement. SASP was not as well tolerated as 5-ASA. REVIEWER'S CONCLUSIONS: The newer 5-ASA preparations were superior to placebo and tended towards therapeutic benefit over SASP. However, considering their relative costs, a clinical advantage to using the newer 5-ASA preparations in place of SASP appears unlikely.

Aminosalicylic Acids↗

Brush-border-enzyme-mediated intestine-specific drug delivery. Amino acid prodrugs of 5-aminosalicylic acid.

5-Aminosalicylic acid (5-ASA) is the active principle of a number of preparations aimed at the treatment of inflammatory bowel diseases, such as Crohn's disease and ulcerative colitis, but its efficacy is limited by early absorption and metabolism. The possibility to exploit the selective hydrolytic activity of brush border enzymes such as aminopeptidase A and carboxypeptidases was studied by preparing the following four amino acid prodrugs of 5-ASA: 5-(N-L-aspartylamino)-2-salicylic acid, disodium salt (18), 5-(N-L-glutamylamino)-2-salicylic acid, disodium salt (19), [(5-aminosalicyl)-L-prolyl]-L-leucine, sodium salt (25), and [[5-(N-L-glutamylamino)salicyl]-L-prolyl]-L-leucine, disodium salt (28). In these compounds, the peptide bond is selectively split by the intestinal brush border aminopeptidase A (compounds 18, 19, and 28) and carboxypeptidases (compounds 25 and 28).

Amino Acids↗

Synthesis and intestinal metabolism of ursodeoxycholic acid conjugate with an antiinflammatory agent, 5-aminosalicylic acid.

5-Aminosalicylic acid conjugate of ursodeoxycholic acid was synthesized in above 90% yield by adding a basic solution of 5-aminosalicylic acid into the mixed anhydride formed with ursodeoxycholic acid and ethyl chloroformate. The 5-aminosalicylic acid conjugate of ursodeoxycholic acid was poorly secreted into the bile and was deconjugated with cholylglycine hydrolase and Clostridium perfringens, that deconjugate naturally occurring glycine and taurine conjugates of bile acids. However, ursodeoxycholic acid 5-aminosalicylic acid conjugate was not absorbed from the duodenum but was concentrated in the colon where it was partially hydrolyzed by the intestinal bacteria to ursodeoxycholic acid and 5-aminosalicylic acid. We believe that this unique conjugation of ursodeoxycholic acid with 5-aminosalicylic acid may facilitate the transport of both 5-aminosalicylic acid and ursodeoxycholic acid to the colon and may be useful for the treatment of colonic inflammatory bowel diseases, ulcerative colitis and Crohn's disease.

Amidohydrolases↗

Synthesis and properties of 5-aminosalicyl-taurine as a colon-specific prodrug of 5-aminosalicylic acid.

5-Aminosalicylic acid (5-ASA) is an active ingredient of therapeutic agents used for Crohn's disease and ulcerative colitis. Because it is absorbed rapidly and extensively in the upper intestine, delivery of the agent specifically to the colon is necessary. We selected taurine as a colon-specific promoiety and designed 5-aminosalicyltaurine (5-ASA-Tau) as a new colon-specific prodrug of 5-aminosalicylic acid (5-ASA). It was expected that introduction of taurine would restrict the absorption of the prodrug and show additive effect to the anti-inflammatory action of 5-ASA after hydrolysis. 5-ASA-Tau was prepared in good yield by a simple synthetic route. The apparent partition coefficient of 5-ASA-Tau in 1-octanol/pH 6.8 phosphate buffer or CHCl3/pH 6.8 phosphate buffer was 0.10 or 0.18, respectively, at 37 degrees C. To determine the chemical and biochemical stability in the upper intestinal environment, 5-ASA-Tau was incubated in pH 1.2 and 6.8 buffer solutions, and with the homogenates of tissue and contents of stomach or small intestine of rats at 37 degrees C. 5-ASA was not detected from any of the incubation medium with no change in the concentration of 5-ASA-Tau. On incubation of 5-ASA-Tau with the cecal and colonic contents of rats, the fraction of the dose released as 5-ASA was 45% and 20%, respectively, in 8 h. Considering low partition coefficient and stability in the upper intestine, 5-ASA-Tau might be nonabsorbable and stable in the upper intestine. After oral administration, it would be delivered to the colon in intact form and release 5-ASA and taurine. These results suggested 5-ASA-Tau as a promising colon-specific prodrug of 5-ASA.

Administration, Oral↗