Clopidogrel

1. Introduction

Clopidogrel, marketed under brand names such as Plavix and Clopilet, is an antiplatelet agent used to prevent blood clots in patients at risk of cardiovascular and cerebrovascular events. It works by inhibiting the P2Y12 receptor on platelets, preventing their aggregation and reducing the risk of arterial thrombotic events.

2. Indications

  • Approved Indications:
    • Prevention of myocardial infarction (MI), stroke, and vascular death in patients with atherosclerosis.
    • Acute coronary syndrome (ACS) (unstable angina or non-ST-elevation myocardial infarction [NSTEMI]).
    • ST-elevation myocardial infarction (STEMI).
    • Prevention of thrombotic events in patients undergoing percutaneous coronary intervention (PCI).
    • Peripheral arterial disease.
  • Off-Label Uses:
    • Secondary prevention of stroke in combination with aspirin (dual antiplatelet therapy).
    • Prevention of thrombosis in atrial fibrillation when anticoagulants are contraindicated.

3. Dosage

  • For Acute Coronary Syndrome (ACS):
    • Loading dose: 300–600 mg orally as a single dose.
    • Maintenance dose: 75 mg once daily.
  • For Stroke, MI, or Peripheral Arterial Disease:
    • 75 mg once daily.
  • Dual Antiplatelet Therapy (DAPT):
    • Used with aspirin (75–100 mg/day) for 6–12 months following PCI or ACS.

4. Administration

  • Can be taken with or without food.
  • Administer at the same time each day to maintain consistent blood levels.

5. Forms Available

  • Tablets: 75 mg, 300 mg.

6. Side Effects

6.1. Common Side Effects

  • Bleeding (e.g., nosebleeds, bruising, prolonged bleeding).
  • Diarrhoea.
  • Indigestion.

6.2. Less Common Side Effects

  • Rash.
  • Headache.

6.3. Rare but Serious Side Effects

  • Gastrointestinal bleeding.
  • Intracranial haemorrhage.
  • Thrombotic thrombocytopenic purpura (TTP).

7. Warnings

  • Increased risk of bleeding; avoid use in patients with active bleeding (e.g., peptic ulcer or intracranial haemorrhage).
  • Use cautiously in patients undergoing surgery; discontinue clopidogrel 5–7 days prior to elective procedures.
  • Avoid concurrent use with other drugs that increase bleeding risk unless medically necessary.

8. Precautions

  • Use with caution in patients with hepatic impairment due to increased bleeding risk.
  • Patients with a genetic variation in CYP2C19 may have reduced efficacy of clopidogrel (poor metabolisers).
  • Avoid grapefruit juice, as it may interfere with clopidogrel activation.

9. Interactions

  • Drug-Drug Interactions:
    • Proton pump inhibitors (e.g., omeprazole, esomeprazole): May reduce the efficacy of clopidogrel by inhibiting CYP2C19.
    • NSAIDs and anticoagulants: Increased risk of bleeding.
    • CYP2C19 inhibitors (e.g., fluoxetine, fluvoxamine): May reduce clopidogrel activation.
  • Drug-Food Interactions:
    • Avoid grapefruit juice as it may interfere with the drug’s activation.

10. Monitoring Parameters

  • Signs of bleeding (e.g., bruising, black stools, prolonged bleeding).
  • Regular platelet function tests in patients with suspected resistance.
  • Monitor liver function in patients with hepatic impairment.

11. Use in Children

  • Not typically recommended, as safety and efficacy in paediatric patients have not been established.

12. Use in Pregnancy

  • Category B: Animal studies show no risk, but human data is limited.
  • Use only if clearly needed and prescribed by a healthcare provider.

13. Use in Elderly

  • No specific dose adjustment required, but monitor closely for bleeding, as elderly patients are at higher risk.

14. Use in Kidney Disease

  • Use with caution in severe renal impairment due to the increased risk of bleeding.

15. Use in Liver Disease

  • Use cautiously in patients with moderate to severe hepatic impairment, as the bleeding risk may be increased.

16. Patient Counselling Points

  • Inform patients of the signs of bleeding (e.g., unusual bruising, black stools) and to report these immediately.
  • Take the medication daily at the same time; do not skip doses.
  • Avoid over-the-counter NSAIDs or aspirin unless prescribed.
  • If surgery is planned, inform the doctor as clopidogrel needs to be stopped 5–7 days prior.
  • Avoid grapefruit juice while on this medication.

17. Table of Brand Names, Manufacturers, and Prices

Brand NameManufacturerPrice (USD)
PlavixSanofi-Aventis$40–60 (30 tablets, 75 mg)
ClopiletSun Pharma$20–30 (30 tablets, 75 mg)
Generic OptionsVarious$10–20 (30 tablets, 75 mg)

18. FAQs (15 Questions)

  1. What is clopidogrel used for?
    Clopidogrel is used to prevent blood clots, reducing the risk of heart attack, stroke, and vascular events.
  2. How does clopidogrel work?
    It inhibits platelet aggregation by blocking the P2Y12 receptor, preventing clots from forming.
  3. How should clopidogrel be taken?
    It should be taken orally once daily, with or without food.
  4. Can clopidogrel cause bleeding?
    Yes, bleeding is a common side effect, including nosebleeds and prolonged bleeding.
  5. Can clopidogrel be stopped suddenly?
    No, abrupt discontinuation can increase the risk of clot formation. Consult a doctor before stopping.
  6. Can clopidogrel be taken during pregnancy?
    It may be used if necessary, but only under a doctor’s supervision.
  7. Can clopidogrel interact with other medications?
    Yes, it interacts with proton pump inhibitors, NSAIDs, and anticoagulants, increasing bleeding risk.
  8. What foods should be avoided with clopidogrel?
    Avoid grapefruit juice as it may reduce the drug’s effectiveness.
  9. What are the common side effects of clopidogrel?
    Bleeding, diarrhoea, and indigestion are common side effects.
  10. Is clopidogrel a blood thinner?
    Yes, it is an antiplatelet agent that prevents blood clots.
  11. How long does clopidogrel take to work?
    It begins to work within 2 hours, with peak effects seen in 3–7 days.
  12. What should I do if I miss a dose?
    Take it as soon as you remember, but skip it if it’s close to the next dose. Do not double up.
  13. Can clopidogrel be used long-term?
    Yes, it is often used for long-term prevention of clotting events, depending on the condition.
  14. Does clopidogrel require routine blood monitoring?
    Routine blood monitoring is not required, but platelet function tests may be performed in some cases.
  15. Can clopidogrel be taken with aspirin?
    Yes, in some cases (e.g., after a heart attack or PCI), clopidogrel is used in combination with aspirin as dual antiplatelet therapy.