Clopidogrel for Veterinary Use

Therapeutic Class: Antiplatelet drug

Species: Dogs and Cats

May Be Prescribed For: Arterial thromboembolism

Clopidogrel is a thienopyridine class, antiplatelet drug. The human trade name is Plavix. It is commonly used in human medicine for stroke patients and those at risk for myocardial infarction due to thrombus formation. Ticlopidine is also a thienopyridine drug, but is less commonly used in veterinary medicine due to a higher incidence of adverse effects when compared to clopidogrel.

Clopidogrel is a pro-drug and must undergo hepatic metabolism to its active metabolite. The mechanism of action is through the irreversible inhibition of the adenosine diphosphate receptor on platelet cell membranes. There is some variability in the literature regarding time to achieve steady state levels (3-7 days). Clopidogrel has a different mechanism of action than aspirin and is frequently combined with aspirin in both human and veterinary patients.

Clopidogrel is an oral antiplatelet-drug that is used in cats with cardiomyopathy, and in dogs with underlying hypercoagulability. Studies in the cat have shown it to have significant anti-platelet drug activity at a wide range of dosages. It is particularly useful in animals that are unable to tolerate aspirin. Although treatment of pre-clinical hypertrophic cardiomyopathy (HCM) remains controversial, there are many clinicians who use clopidogrel and other cardiac drugs in the asymptomatic cat with HCM.

Clopidogrel is used in dogs for the treatment of immune-mediated hemolytic anemia. Although there are multiple reports regarding its use in the dog, there is not as much clinical experience in the dog as in the cat.

Clopidogrel is generally well tolerated in the cat. The most commonly-reported side effects are nausea and anorexia. These side effects may be lessened by administration with food.

Extrapolating from the precautions in human medicine would indicate that clopidogrel should not be used in animals with active bleeding. There is no specific precautionary information available for cats and dogs.

• Clopidogrel has been used with aspirin and heparin (including low molecular weight heparin.) Increased risk of major bleeding should be considered.

• Clopidogrel may interfere with the metabolism of NSAIDs ,phenytoin, toresemide, and warfarin.

• There may be an increased risk of bleeding when clopidogrel is used NSAIDs, warfarin, and aspirin.

• There is a wide margin of safety for clopidogrel. Based on experience in human medicine, bleeding and vomiting are the most likely clinical signs of overdose.

• Platelet transfusion may be considered in an acute overdose.