Clopidogrel warnings and precautions
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Jesus Rosario Hernandez, M.D. [2]
Warnings and Precautions
5.1 Diminished Antiplatelet Activity Due to Impaired CYP2C19 Function
Clopidogrel is a prodrug. Inhibition of platelet aggregation by clopidogrel is achieved through an active metabolite. The metabolism of clopidogrel to its active metabolite can be impaired by genetic variations in CYP2C19 [see Boxed Warning] and by concomitant medications that interfere with CYP2C19.
Proton Pump Inhibitors
Avoid concomitant use of Plavix with omeprazole or esomeprazole because both significantly reduce the antiplatelet activity of Plavix [see Drug Interactions (7.1) and Dosage and Administration (2.4)].
5.2 General Risk of Bleeding
Thienopyridines, including Plavix, increase the risk of bleeding. If a patient is to undergo surgery and an antiplatelet effect is not desired, discontinue Plavix five days prior to surgery. In patients who stopped therapy more than five days prior to CABG the rates of major bleeding were similar (event rate 4.4% Plavix + aspirin; 5.3% placebo + aspirin). In patients who remained on therapy within five days of CABG, the major bleeding rate was 9.6% for Plavix + aspirin, and 6.3% for placebo + aspirin. Thienopyridines inhibit platelet aggregation for the lifetime of the platelet (7–10 days), so withholding a dose will not be useful in managing a bleeding event or the risk of bleeding associated with an invasive procedure. Because the half-life of clopidogrel's active metabolite is short, it may be possible to restore hemostasis by administering exogenous platelets; however, platelet transfusions within 4 hours of the loading dose or 2 hours of the maintenance dose may be less effective.
5.3 Discontinuation of Plavix
Avoid lapses in therapy, and if Plavix must be temporarily discontinued, restart as soon as possible. Premature discontinuation of Plavix may increase the risk of cardiovascular events.
5.4 Patients with Recent Transient Ischemic Attack (TIA) or Stroke
In patients with recent TIA or stroke who are at high risk for recurrent ischemic events, the combination of aspirin and Plavix has not been shown to be more effective than Plavix alone, but the combination has been shown to increase major bleeding.
5.5 Thrombotic Thrombocytopenic Purpura (TTP)
TTP, sometimes fatal, has been reported following use of Plavix, sometimes after a short exposure (<2 weeks). TTP is a serious condition that requires urgent treatment including plasmapheresis (plasma exchange). It is characterized by thrombocytopenia, microangiopathic hemolytic anemia (schistocytes [fragmented RBCs] seen on peripheral smear), neurological findings, renal dysfunction, and fever [see Adverse Reactions (6.2)].
5.6 Cross-Reactivity among Thienopyridines
Hypersensitivity including rash, angioedema or hematologic reaction have been reported in patients receiving Plavix, including patients with a history of hypersensitivity or hematologic reaction to other thienopyridines [see Contraindications (4.2) and Adverse Reactions (6.2)].[1]
References
Adapted from the FDA Package Insert.