title: Is N-acetylation of 5-aminosalicylic acid reversible in man?
abstract: In two healthy male subjects the disposition of deuterated N-(2H3) acetyl-5-aminosalicylic acid (d3-ac-5-AS) was investigated after a single rectal dose of 500 mg d3-ac-5-AS. Urine and plasma were analysed by h.p.l.c. and gas chromatography mass-spectrometry. Peak concentrations of around 0.5 microgram/ml occurred within 6 h and plasma concentrations declined thereafter with a half-life (t1/2) of about 6 h which was confirmed by urinary excretion data. Renal clearance of d3-ac-5-AS ranged between 200 and 300 ml/min and only 4.4-11.2% of the dose could be recovered in the 48 h urine. Since no undeuterated ac-5-AS could be detected in any of the plasma and urine samples an irreversible acetylation of 5-AS is assumed in man.
mesh_terms: D000107:Acetylation; D000328:Adult; D000636:Aminosalicylic Acids / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008297:Male; D019804:Mesalamine
chemical_list: D000636:Aminosalicylic Acids; D019804:Mesalamine; C028836:N-acetyl-5-aminosalicylic acid