title: Intake and excretion of disodium monomethylarsonate in horses: a speciation study.
abstract: Capillary electrophoresis coupled to inductively coupled plasma mass spectrometry was used in a speciation study on disodium monomethylarsonate (DS-MMA(V)) and its metabolites in horses, to which the drug was administered by intramuscular injection on five consecutive days at a single arsenic dosage of 270 mg day(-1). Samples of urine, whole blood, plasma, and mane hair were analyzed before, during, and after drug administration. The data show that blood clearing and urinary excretion of MMA is a fast process following first-order kinetics with biological half-lives of about 38 h and 44 h for urine and plasma, respectively. In the time period of 9 days studied, the only metabolite detected in urine was dimethylarsinic acid (DMA(V)), which 4 days after the last drug administration accounted for up to 75% of the total excreted arsenic species. This shows, for the first time, that biomethylation of MMA(V) to DMA(V) is the principal metabolic pathway of this drug in horses. Although DS-MMA(V) was administered only during a short 5-day period, an up to six fold increase of arsenic could be measured in the newly grown mane hair.
authors.affiliation: Department of Analytical Chemistry, Fluminense University, Niterói, Brazil.
authors.forename: Roberta A
authors.initials: RA
authors.lastname: Assis
authors.forename: Ivo L
authors.initials: IL
authors.lastname: Kuchler
authors.forename: Norbert
authors.initials: N
authors.lastname: Miekeley
authors.forename: Marta B
authors.initials: MB
authors.lastname: Tozzi
mesh_terms: D000818:Animals; D001151:Arsenic / Q000008:administration & dosage / Q000032:analysis; D001152:Arsenicals / Q000097:blood* / Q000378:metabolism / Q000652:urine*; D002101:Cacodylic Acid / Q000378:metabolism / Q000652:urine; D019075:Electrophoresis, Capillary; D006197:Hair / Q000737:chemistry; D006736:Horses; D007273:Injections, Intramuscular; D013058:Mass Spectrometry / Q000379:methods; D008745:Methylation; D012680:Sensitivity and Specificity; D013997:Time Factors
chemical_list: D001152:Arsenicals; D002101:Cacodylic Acid; C020300:monomethylarsonic acid; D001151:Arsenic