Use of antidepressants with pharmacogenetic prescribing guidelines in a 10-year depression cohort of adult primary care patients.

Objective To describe the usage patterns of antidepressants with publishedCYP2D6- andCYP2C19-based prescribing guidelines among depressed primary care patients and estimate the proportion of patients taking antidepressants not recommended for them based on theirCYP2C19andCYP2D6genotype-predicted metabolizer status. Methods Medication use and pharmacogenetic testing results were collected on 128 primary care patients enrolled in a 10-year depression cohort study. At each 12-month interval, we calculated the proportion of patients that: (1) reported use of one or more of the 13 antidepressant medications (i.e. amitriptyline, citalopram, escitalopram, clomipramine, desipramine, doxepin, fluvoxamine, imipramine, nortriptyline, paroxetine, sertraline, trimipramine, venlafaxine) with publishedCYP2D6- andCYP2C19-based prescribing guidelines, (2) were taking an antidepressant that was not recommended for them based on theirCYP2C19andCYP2D6genotype-predicted metabolizer phenotype, and (3) switched medications from the previous 12-month interval. Results The annual proportion of individuals taking an antidepressant with aCYP2D6- andCYP2C19-based prescribing guidelines ranged from 45 to 84%. The proportion of participants that used an antidepressant that was not recommended for them, based on availableCYP2D6andCYP2C19metabolizer phenotype, ranged from 18 to 29% and these individuals tended to switch medications more frequently (10%) compared to their counterparts taking medication aligned with their metabolizer phenotype (6%). Conclusion One-quarter of primary care patients used an antidepressant that was not recommended for them based onCYP2D6- andCYP2C19-based prescribing guidelines and switching medications tended to be more common in this group. Studies to determine the impact ofCYP2D6andCYP2C19genotyping on reducing gene-antidepressant mismatches are warranted.