Availability of CYP2D6 genotyping results in general practitioner and community pharmacy medical records

Abstract

Aim: To investigate the availability of CYP450–2D6 (CYP2D6) genotyping results in general practitioner (GP) and/or community pharmacy records, and the influence thereof on psychotropic CYP2D6 substrate dosing. Materials & methods: Primary outcome was the percentage of patients genotyped for CYP2D6 with their genotype/phenotype registered in GP and/or pharmacy records. Secondary outcome was the number of defined daily doses of psychotropic CYP2D6 substrates prescribed after genotyping. Results: For 216 out of 1307 eligible patients, medication overviews could be obtained. Genotyping results were available at GPs for 3.1% and at pharmacies for 5.9%. The average psychotropic CYP2D6 substrate dose was not different between any non-extensive metabolizer group and extensive metabolizer group (all p ≥ 0.486). Conclusion: Valuable information for individualizing psychiatric pharmacotherapy is lost on a large scale.