AHS 2022 | The effect of pharmacogenomic phenotypes on the adequate dosing of verapamil for migraine prevention

Verapamil has a wide range of dosing in primary headache disorders, but there is no reliable way to predict the effective and tolerable doses for an individual. Yi-Chieh Chen, PharmD, Mayo Clinic, Rochester, MN, discusses a pilot study investigating the factors affecting the efficacy and safety of verapamil for migraine using pharmacogenomic reports in electronic medical records (EMRs). This retrospective study investigated 33 adult patients who had used verapamil for migraine and had a pharmacogenomic report in the EMRs. Results showed a wide range of minimum effective (range 20 to 320 mg) and maximum tolerable (range 20 to 480 mg) verapamil doses. The study also investigated six metabolic enzymes relevant to verapamil. Most patients were CYP1A2 rapid metabolizers, CYP2B6 intermediate metabolizers, and CYP3A4 normal metabolizers. There was a wide variety of CYP2C9, CYP2D6, and CYP3A5 phenotypes. However, after adjusting for age, sex, BMI, and smoking status, there was no association between different phenotypes and verapamil doses. The pilot study demonstrated that there was a wide range of minimum effective and maximum tolerable verapamil doses in patients with a variety of pharmacogenomic phenotypes in migraine prevention – however, the use of a small sample size and utilizing an existing pharmacogenomic report were limiting factors. This interview took place during the 2022 American Headache Society (AHS) Meeting in Denver, CO.