Raw research findings for this medication. Mostly single studies, not curated or confirmed robust.
Quinidine is a class 1A antiarrhythmic, the mirror image of quinine from cinchona bark. It blocks sodium and potassium channels in the heart. Once used widely for atrial fibrillation, it is now used rarely, for example in Brugada syndrome and some other inherited rhythm disorders, and at low dose with dextromethorphan (Nuedexta). It is a very strong blocker of CYP2D6.
Quinidine is broken down by CYP3A4, and it so strongly blocks CYP2D6 that it turns people into temporary CYP2D6 poor metabolizers, which is the reason it is paired with dextromethorphan and is used in research to study CYP2D6. The gene studies listed looked at KCNE1 and KCNH2, potassium channel genes, for drug-induced QT prolongation. There is no CPIC or DPWG guideline.
Every published finding on gene variants and Quinidine. Upload your DNA file to see which of these rows apply to you.
PharmGKB weighs all studies of a variant and rates how strong the evidence is, from 1A (strongest) to 4.
KCNE1 rs1805128: Level 3. Toxicity. 1.
KCNH2 rs104894021: Level 3. Efficacy: short qt syndrome 1. 1.
Study findings and evidence levels: PharmGKB (CC BY-SA 4.0). Guidelines: CPIC and DPWG, as bundled in PharmCAT. Most studies were done mainly in people of European ancestry.
More drugs from the same category
Not a prescribing recommendation. This page is educational information about pharmacogenomic research and clinical guidelines - it is not medical or dosing advice, and not a prediction of how any medication will work for you. Never start, stop, or change a medication or dose based on it; talk to your doctor or pharmacist, who can order clinical-grade testing if appropriate.
Content updated September 2026.
ReadYourDNA provides educational interpretation of DNA data you already have. It is not diagnostic, not a substitute for professional medical advice, diagnosis, or treatment, and is not intended to diagnose, treat, cure, or prevent any disease. Talk to a clinician before acting on any result.
Raw DNA Data Reports for 23andMe & AncestryDNA · About ReadYourDNA · FAQ · Methodology & Science · Pricing · Support and complaints · Legal & Contact · Health Traits · Pharmacogenomics · Carrier Status · Variant Explorer · The Human Karyotype · Privacy Policy · Terms of Service · Accessibility · Consumer Health Data Privacy · Your Privacy Choices · Editorial Standards · Your Data, Checkable · Sample Report · ReadYourDNA and Promethease compared · What is inside a 23andMe raw data file · What is inside an AncestryDNA raw data file · What a chatbot can and cannot do with your raw DNA file · Where a raw DNA file can still be uploaded in 2026
Written, maintained and operated by Martin Pechhacker, sole proprietor, Vienna, Austria. Trade register GISA 40064420. support@readyourdna.com