{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,29]],"date-time":"2026-09-29T16:04:02Z","timestamp":1790697842832,"version":"4.1.0"},"reference-count":46,"publisher":"Wiley","issue":"2","license":[{"start":{"date-parts":[[2025,12,3]],"date-time":"2025-12-03T00:00:00Z","timestamp":1764720000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2025,12,3]],"date-time":"2025-12-03T00:00:00Z","timestamp":1764720000000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"funder":[{"DOI":"10.13039\/501100006041","name":"Innovate UK","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100006041","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Br J Clin Pharmacol"],"published-print":{"date-parts":[[2026,2]]},"abstract":"<jats:p>\n                    Clopidogrel, an antiplatelet agent, is currently licensed in the United Kingdom for the prevention and treatment of atherothrombotic events in cerebrovascular disease, coronary artery disease and peripheral arterial disease. Clopidogrel requires metabolic activation by the cytochrome P450 enzyme CYP2C19 to be effective. CYP2C19 is encoded by a polymorphic gene; variants in the\n                    <jats:italic>CYP2C19<\/jats:italic>\n                    gene, which vary in frequency in different ethnic groups can abolish, reduce or increase enzyme activity, thereby affecting the conversion of clopidogrel to its active metabolite. Individuals who have either one or two loss\u2010of\u2010function alleles are referred to as intermediate and poor metabolisers, respectively, and in these patients, the clinical effectiveness of clopidogrel is reduced or absent. Any patient about to be prescribed clopidogrel, regardless of the underlying indication, should have pharmacogenetic testing to identify clinically relevant\n                    <jats:italic>CYP2C19<\/jats:italic>\n                    variants, where testing is available, to optimize their antiplatelet therapy. Clopidogrel use should be avoided in patients with an intermediate or poor CYP2C19 metaboliser phenotype in all approved indications and alternative treatment regimens used as detailed in this guideline. Our guideline is compatible with other international pharmacogenetic prescribing guidelines, but we also provide recommendations in other areas. Summary guidance on a page is provided for each of the indications in Boxes 1\u20133. This guideline is grounded in the latest evidence in this field but cannot account for all individual factors relevant to patient care. Therefore, prescribers must conduct a thorough assessment of each patient's risk\u2013benefit profile, ensuring that therapy is optimized to maximize benefits while minimizing potential harms.\n                  <\/jats:p>","DOI":"10.1002\/bcp.70370","type":"journal-article","created":{"date-parts":[[2025,12,4]],"date-time":"2025-12-04T00:00:14Z","timestamp":1764806414000},"page":"329-347","source":"Crossref","is-referenced-by-count":21,"title":["<i>CYP2C19<\/i>\n                    genotype testing for clopidogrel: A guideline developed by the UK Centre of Excellence in Regulatory Science and Innovation in Pharmacogenomics (CERSI\u2010PGx)"],"prefix":"10.1002","volume":"92","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-2538-3832","authenticated-orcid":false,"given":"Cinzia","family":"Dello Russo","sequence":"first","affiliation":[{"name":"Department of Pharmacology and Therapeutics, Institute of Systems, Molecular and Integrative Biology University of Liverpool  Liverpool UK"},{"name":"Department of Healthcare Surveillance and Bioethics, Section of Pharmacology Universit\u00e0 Cattolica del Sacro Cuore \u2010 Fondazione Policlinico Universitario A. Gemelli, IRCCS  Rome Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0003-3941-8375","authenticated-orcid":false,"given":"Iain","family":"Frater","sequence":"additional","affiliation":[{"name":"School of Cardiovascular and Metabolic Health University of Glasgow  Glasgow UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rebecca","family":"Kuruvilla","sequence":"additional","affiliation":[{"name":"Department of Pharmacology and Therapeutics, Institute of Systems, Molecular and Integrative Biology University of Liverpool  Liverpool UK"},{"name":"The Wolfson Centre for Personalised Medicine, Centre for Drug Safety Science University of Liverpool  Liverpool UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Stefanie","family":"Lip","sequence":"additional","affiliation":[{"name":"School of Cardiovascular and Metabolic Health University of Glasgow  Glasgow UK"},{"name":"Queen Elizabeth University Hospital  Glasgow UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hannah","family":"O'Neill","sequence":"additional","affiliation":[{"name":"East of Scotland Vascular Network, Department of Vascular Surgery University of Dundee  Dundee UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kerry","family":"Burke","sequence":"additional","affiliation":[{"name":"Department of Vascular Surgery, Manchester Royal Infirmary Manchester University NHS Foundation Trust  Manchester UK"},{"name":"Manchester Centre for Genomic Medicine St Mary's Hospital, Manchester University NHS Foundation Trust  Manchester UK"},{"name":"Division of Evolution, Infection and Genomics, School of Biological Sciences The University of Manchester  Manchester UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Vicky","family":"Chaplin","sequence":"additional","affiliation":[{"name":"Genomics Unit NHS England  London UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Alexander S. 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