 No free pyrrolidine will be detected in the urine.Molecularly, this is seen as demethylenation of methylenedioxypyrovalerone (CYP2D6), followed by methylation of the aromatic ring via catechol-O-methyl transferase.Hydroxylation of both the aromatic ring and side chain then takes place, followed by an oxidation of the pyrrolidine ring to the corresponding lactam, with subsequent detachment and ring opening to the corresponding carboxylic acid.