Thoughtful Clinical Use of Pharmacogenetics in Child and Adolescent Psychopharmacology

AACAP's recent policy statement on Clinical Use of Pharmacogenetic Tests in Prescribing Psychotropic Medications for Children and Adolescents¹ recommends that "clinicians avoid using pharmacogenetic testing to select psychotropic medications in children and adolescents." We agree that there are limitations to the nascent evidence base for using pharmacogenetics, especially in combinatorial form (eg, test results that bin medications based on multiple genes). However, all-or-nothing recommendations fail to recognize the nuance and context of this testing and contrast with the AACAP Facts for Families on pharmacogenetic testing. Moreover, pharmacogenetic testing may inform dosing for antidepressants that are commonly used in child and adolescent psychiatry (eg, sertraline, escitalopram, citalopram, fluvoxamine) as well as the tolerability of some psychotropic medications. With this in mind, we wish to remind the AACAP community of the accumulating evidence and to highlight important principles of pharmacogenetic testing in youths. Specifically: 1) pharmacogenetic testing is not always performed by commercial companies and is not always combinatorial; 2) dosing recommendations or assessment of risk for severe hypersensitivity reactions are based on pharmacogenetics in the Food and Drug Administration (FDA)-approved product inserts for several medications commonly prescribed to children (eg, citalopram, aripiprazole, atomoxetine, carbamazepine, oxcarbazepine at www.fda.gov/drugs/science-and-research-drugs/table-pharmacogenomic-biomarkers-drug-labeling); 3) expert consensus guidelines for dosing or identifying hypersensitivity risk for these drugs are available from the National Institutes of Health (NIH)-supported Clinical Pharmacogenetics Implementation Consortium (CPIC, www.cpicpgx.org/), which provides transparent, regularly updated, and evidence-based evaluations of pharmacogenetic data;² and 4) randomized trials are not required for clinical dose adjustments; for example, dose adjustments because of decreased hepatic function or concomitant interacting medications are based on pharmacokinetic data, similar to many pharmacokinetic gene-based recommendations from CPIC.