Pharmacology
Cardiovascular
What is the mechanism of action of clopidogrel:
Answer:
Clopidogrel, a thienopyridine derivative, inhibits the binding of ADP to its platelet receptor (P2Y12 ADP-receptor), inhibiting platelet adhesion and aggregation.Clopidogrel
Pharmacology / Cardiovascular
Last Updated: 17th April 2019
Antiplatelet drugs decrease platelet aggregation and inhibit thrombus formation in the arterial circulation, because in faster-flowing vessels, thrombi are composed mainly of platelets with little fibrin.
Mechanism of Action
Clopidogrel, a thienopyridine derivative, inhibits the binding of ADP to its platelet receptor (P2Y12 ADP-receptor), inhibiting platelet adhesion and aggregation.
Indications
Clopidogrel is used for:
- the prevention of atherothrombotic events in patients with a history of symptomatic ischaemic disease
- the management of ACS (in combination with low-dose aspirin)
- the prevention of atherothrombotic events in percutaneous coronary intervention (in combination with low-dose aspirin)
- the prevention of atherothrombotic and thromboembolic events in patients with atrial fibrillation (who cannot take warfarin) and in stroke (in patients who cannot take aspirin)
Contraindications
Clopidogrel should be avoided in:
- People with active pathological bleeding, such as peptic ulcer or intracranial haemorrhage
- People with severe hepatic impairment
- Women who are pregnant or breastfeeding
Clopidogrel should be used with caution in people who may be at high risk of increased bleeding, for example those receiving treatment with warfarin, other anti-platelets or other drugs known to increase gastrointestinal bleeding (such as NSAIDs, SSRIs and corticosteroids).
Side Effects
- Clopidogrel is associated with an increased risk of bleeding (for example gastrointestinal bleeds)
- Other common adverse effects include diarrhoea, abdominal pain, and dyspepsia
- Clopidogrel is known to cause pruritus and urticaria, but these adverse reactions are generally uncommon
- Gynaecomastia is a rare adverse effect of clopidogrel
- Thrombotic thrombocytopenic purpura is a very rare adverse effect of clopidogrel, and it sometimes occurs after a short exposure to clopidogrel
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
