Isolation and identification of 4-hydroxysulfamerazine and preliminary studies on its pharmacokinetics in dogs

For the following compounds: sulfamerazine, 4- hydroxysulfamerazine , N4- acetylsulfamerazine , N4-acetyl-4- hydroxysulfamerazine , the following data are reported: biosynthesis in the dog, isolation, identification by MS and NMR, TLC (Rf values) and HPLC (capacity factors and molar extinction), half-life of elimination, metabolism, renal excretion and protein binding in dog. Dogs are unable to acetylate sulfamerazine, but eliminate predominantly by hydroxylation of the N1-substituent. Administered N4- acetylsulfamerazine is predominantly eliminated by deacetylation to sulfamerazine which in turn is hydroxylated. The renal clearances of sulfamerazine and N4- acetylsulfamerazine in the dog are identical. The renal excretion of both compounds proceeds by the passive processes of glomerular filtration and tubular reabsorption. 4- Hydroxysulfamerazine and its glucuronide have a higher renal clearance than sulfamerazine.