CLOPIDOGREL BISULFATE
Clinical safety rating: safe
Animal studies have demonstrated safety
Clopidogrel is a prodrug that requires hepatic metabolism via CYP2C19 to an active thiol metabolite. This metabolite irreversibly inhibits the P2Y12 component of ADP receptors on platelets, preventing ADP-induced platelet aggregation.
| Metabolism | Clopidogrel is a prodrug metabolized via two pathways: (1) esterase-mediated hydrolysis to inactive carboxylic acid derivative (85%); (2) CYP450-mediated oxidation to active thiol metabolite. CYP2C19 plays a major role in both steps of activation; CYP1A2, CYP2B6, and CYP3A4 contribute to the first step. |
| Excretion | Renal 50%, fecal 46%. Metabolized via CYP2C19; parent drug and metabolites excreted in urine and feces. |
| Half-life | Terminal half-life of clopidogrel's active metabolite is approximately 30 minutes; for the inactive metabolite, half-life is about 8 hours. Clinical context: The short half-life of the active metabolite supports once-daily dosing, with platelet inhibition recovery within 5 days after discontinuation. |
| Protein binding | Clopidogrel and its inactive metabolite: 94-98% bound to albumin. Active metabolite: approximately 98% bound to albumin. |
| Volume of Distribution | Vd: approximately 1.4 L/kg (steady state). Clinical meaning: Moderate distribution into body tissues, consistent with binding to plasma proteins. |
| Bioavailability | Oral: approximately 50% bioavailability of active metabolite due to extensive first-pass metabolism via CYP2C19. |
| Onset of Action | Oral: 2 hours for significant platelet inhibition; maximal effect within 4-6 hours after a loading dose (300-600 mg). |
| Duration of Action | Platelet inhibition persists for 5-7 days after discontinuation, consistent with the irreversible binding to P2Y12 receptor. |
75 mg orally once daily; loading dose: 300 mg or 600 mg orally as a single dose for acute coronary syndrome or percutaneous coronary intervention.
| Dosage form | TABLET |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment (GFR ≥30 mL/min). Insufficient data for severe renal impairment (GFR <30 mL/min); use with caution. |
| Liver impairment | Contraindicated in severe hepatic impairment (Child-Pugh class C). Use with caution in moderate impairment (Child-Pugh class B); no dose adjustment established. |
| Pediatric use | Not FDA-approved for pediatric use; safety and efficacy not established. |
| Geriatric use | No specific dose adjustment recommended; monitor for bleeding risk due to age-related increased sensitivity. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Proton pump inhibitors like omeprazole may reduce its antiplatelet effect Risk of bleeding including life-threatening and fatal bleeding.
| Breastfeeding | Clopidogrel is excreted into human milk in low amounts; M/P ratio is approximately 0.5. Limited data suggest no adverse effects in breastfed infants. Caution is advised, especially in preterm or thrombocytopenic infants. |
| Teratogenic Risk | Clopidogrel bisulfate is pregnancy category B. Animal studies have not shown fetal harm, but adequate human studies are lacking. In the first trimester, theoretical risk of bleeding. In second and third trimesters, increased risk of maternal hemorrhage and fetal bleeding, particularly near delivery. Use only if benefit outweighs risk. |
■ FDA Black Box Warning
BOXED WARNING: Clopidogrel effectiveness depends on CYP2C19 activation. In patients who are CYP2C19 poor metabolizers, clopidogrel at recommended doses forms less active metabolite and has reduced antiplatelet activity. Tests are available to identify CYP2C19 genotype. Consider alternative treatment strategies in poor metabolizers.
| Common Effects | Bleeding |
| Serious Effects |
["Active pathological bleeding (e.g., peptic ulcer, intracranial hemorrhage)","Hypersensitivity to clopidogrel or any component of the product"]
| Precautions | ["Increased risk of bleeding; discontinue 5 days prior to elective surgery if antiplatelet effect not desired","Thrombotic thrombocytopenic purpura (TTP) reported rarely","Reduced efficacy in CYP2C19 poor metabolizers; consider genotyping or alternative P2Y12 inhibitor","Cross-reactivity in patients with allergy to other thienopyridines (e.g., ticlopidine)","Use with caution in patients with severe hepatic impairment"] |
Loading safety data…
| Fetal Monitoring | Monitor for signs of bleeding in mother (e.g., epistaxis, bruising) and fetal distress via ultrasound and fetal heart rate monitoring. Coagulation parameters (PT, aPTT, platelet counts) should be checked periodically. Assess for placental abruption if bleeding occurs. |
| Fertility Effects | Animal studies show no impairment of fertility at clinically relevant doses. No human data on fertility effects; theoretical risk of reduced implantation due to antiplatelet effects is unlikely at standard doses. |