An early study by the Vanderbilt group demonstrated with mephenytoin that CYP2C19 EMs exhibited a 3C8 fold increase in the ratio of urinary ratio of R:S mephenytoin and a 40C180% increase in the 0C8 hour urinary excretion of the 4-hydroxy-mephenytoin … Continue reading An early study by the Vanderbilt group demonstrated with mephenytoin that CYP2C19 EMs exhibited a 3C8 fold increase in the ratio of urinary ratio of R:S mephenytoin and a 40C180% increase in the 0C8 hour urinary excretion of the 4-hydroxy-mephenytoin metabolite