Excretion Following oral dosing of radiolabeled methylphenidate in humans, about 90% on the radioactivity was recovered in urine. The key urinary metabolite was ritalinic acid, accounting for roughly eighty% with the dose. Methylphenidate did not result in any rise in tumors within a lifetime carcinogenicity analyze completed in F344 rats; https://randallr752pzi1.bloggactivo.com/profile