Pharmacogenetics of Cardiovascular Antithrombotic Therapy

2. Pharmacogenetics of Cardiovascular Antithrombotic Therapy CH3 O C O Clopidogrel (oral ingestion of pro-drug) CH3 O N O C S Cl N HOOC Intestinal absorption MDR-1 Cl HS CYP Enzyme System Two sequential steps: One step: CYP3A4, CYP3A5, CYP2C9, CYP1A2 Both steps: CYP2B6, CYP2C19 Hepatic generation of active metabolite Genetic targets Platelet Membrane Receptors P2Y12, GPIIb/IIIa, GPIa Platelet inhibition CYP = cytochrome P450. GP = glycoprotein. MDR = multidrug resistance protein. Marín F, et al. J Am CollCardiol. 2009;54:1041-1057.

3. Clopidogrel ─ Pharmacogenetic Information WARNING: DIMINISHED EFFECTIVENESS IN POOR METABOLIZERS The effectiveness of clopidogrel is dependent on its activation to an active metabolite by the cytochrome P450 (CYP) system, principally CYP2C19. Clopidogrel at recommended doses forms less of that metabolite and has a smaller effect on platelet function in patients who are CYP2C19 poor metabolizers. Poor metabolizers with ACS or who are undergoing PCI treated with clopidogrel at recommended doses exhibit higher cardiovascular event rates than patients with normal CYP2C19 function. Tests are available to identify a patient's CYP2C19 genotype; these tests can be used as an aid in determining therapeutic strategy. Consider alternative treatment or treatment strategies in patients identified as CYP2C19 poor metabolizers. ACS = acute coronary syndrome. PCI = percutaneous coronary intervention. Plavix®(clopidogrel bisulfate) tablets [package insert]. Bridgewater, NJ: Bristol-Myers Squibb Company/sanofi-aventis Partnership; 2009.

4. 2009 Updated Labeling for Clopidogrel – PPI Interaction FDA-required label changes1,2: • Warning: Co-administration of clopidogrel with omeprazole, a PPI that is an inhibitor of CYP2C19, reduces the pharmacological activity of clopidogrel if given concomitantly or if given 12 hours apart. • Drug-drug interactions: Avoid concomitant use of drugs that inhibit CYP2C19, including omeprazole, esomeprazole, cimetidine, fluconazole, ketoconazole, voriconazole, etravirine, felbamate, fluoxetine, fluvoxamine, and ticlopidine. • Based on PK/PD studies showing that concomitant omeprazole reduced clopidogrel active metabolite and effect on platelets.1 • Did not include COGENT study data2 • EMEA warning extends to discourage concomitant use of all PPIs.3 • Concomitant use of drugs that inhibit CYP2C19 discouraged; concomitant use of any PPI should be avoided unless absolutely necessary.4 EMEA = European Medicines Agency. PD = pharmacodynamic. PK = pharmacokinetic. PPI = proton pump inhibitor.1. FDA. Available at: http://www.fda.gov/Drugs/DrugSafety/PostmarketDrugSafetyInformationforPatientsandProviders/DrugSafety InformationforHeathcareProfessionals/ucm190787.htm. Accessed September 22, 2012. 2. Plavix®(clopidogrel bisulfate) tablets [package insert]. Bridgewater, NJ: Bristol-Myers Squibb Company/sanofi-aventis Partnership; 2009. 3. Wathion N. Available at: http://www.emea.europa.eu/humandocs/PDFs/EPAR/Plavix/32895609en.pdf. Accessed September 22, 2012. 4. Plavix®(clopidogrel bisulfate) tablets [summary of product characteristics]. Paris, France: Bristol-Myers Squibb Company/sanofi-aventis Partnership; 2009.

5. ACC/AHA/SCAI Guideline Recommendations Regarding Genetic Testing and Concurrent Use of PPI and Antiplatelet Therapy Genetic Testing: • Genetic testing might be considered to identify whether a patient at high risk for poor clinical outcomes is predisposed to inadequate platelet inhibition with clopidogrel – Class IIb - Level C evidence • When a patient predisposed to inadequate platelet inhibition with clopidogrel is identified by genetic testing, treatment with an alternate P2Y12 inhibitor (eg, prasugrel or ticagrelor) might be considered – Class IIb - Level C evidence • Routine clinical use of genetic testing to screen patients treated with clopidogrel who are undergoing PCI is not recommended – Class III (no benefit) - Level C evidence PPI Use: • PPIs should be used in patients with a history of prior GI bleeding who require dual antiplatelet therapy – Class I - Level C evidence • PPI use is reasonable in patients with increased risk of gastrointestinal bleeding (advanced age, concomitant use of warfarin, steroids, NSAIDs, H. pylori infection, etc.) who require dual antiplatelet therapy – Class IIa- Level C evidence • Routine use of a PPI is not recommended for patients at low risk of GI bleeding who have much less potential to benefit from prophylactic therapy – Class III (no benefit) - Level C evidence GI = gastrointestinal. NSAIDs = nonsteroidal anti-inflammatory drugs. Levine GN, et al. J Am CollCardiol. 2011;58:e44-e122.