When preventing myocardial infarction and cerebral infarction, which one is better, aspirin or clopidogrel?

Someone left a message for Huazi, asking which is better to choose between aspirin and clopidogrel when preventing myocardial infarction and cerebral infarction? Huazi said that these two drugs belong to the same class of drugs, both of which are antiplatelet drugs. They have similar effects and can be used in combination with each other. When using them, aspirin is usually the first choice. When patients have contraindications to aspirin or cannot tolerate the adverse reactions of aspirin, clopidogrel is considered.

1. When aspirin and clopidogrel are used to prevent myocardial infarction and cerebral infarction, antiplatelet drugs play an important role in the treatment plan and are indispensable. The main cause of myocardial infarction and cerebral infarction is the rupture of atherosclerotic plaques, which causes platelet aggregation and then leads to thrombosis. Therefore, as long as the activity of platelets is inhibited, thrombosis can be prevented when plaques rupture, thus preventing the occurrence of the disease.

There are many factors that induce platelet aggregation. Thromboxane A2 (TXA2) produced by platelet cyclooxygenase (COX) and the effect of adenosine diphosphate (ADP) on ADP receptors on platelets can cause platelet aggregation.

Aspirin works by binding to COX and inhibiting the production of TXA2, while clopidogrel blocks the P2Y12 receptor on the platelet membrane, preventing the binding of platelets to ADP. Although the two drugs have different working mechanisms, "all roads lead to Rome", and they will eventually inhibit platelet aggregation.

2. Differences between the two drugs in use Since the two drugs have the same effect, why does Huazi say that aspirin should be preferred? This is because there are differences in the effects of the two drugs. After oral absorption, aspirin will directly bind to platelets and exert an antiplatelet effect. Moreover, the effect of aspirin is irreversible and will be continuously inhibited during the life cycle of platelets.

Clopidogrel is a prodrug that is inactive by itself. It needs to be metabolized by the CYP2C19 enzyme in liver cells before it releases active substances and exerts its antiplatelet effect. If the amount of CYP2C19 enzyme in the human body is insufficient or its metabolic activity is low, it will not have an effective effect.

There are genetic differences between different races. Among white people, the number of people with low CYP2C19 enzyme activity is about 3-5%, among black people it is 1-7.5%, and among Oriental people it is 11-23%. In other words, a considerable number of people in China will not have an antiplatelet effect after taking clopidogrel, and cannot effectively reduce the risk of cardiovascular and cerebrovascular diseases.

Therefore, before using clopidogrel, it is best to do a CYP2C19 gene test to confirm that the drug is effective, or use ticagrelor, which does not require metabolic processes in the body. However, whether it is a genetic test or the use of ticagrelor, it will increase the patient's medication costs, so aspirin is the most cost-effective choice.

3. Differences in side effects between the two drugs: Aspirin and clopidogrel can weaken blood coagulation function and cause side effects such as increased bleeding risk, such as nose bleeding, gum bleeding, gastrointestinal bleeding, subcutaneous bleeding, etc. In terms of adverse reactions that cause bleeding, the two drugs are not much different.

However, aspirin's inhibition of cyclooxygenase will reduce the production of prostaglandins that protect the digestive tract mucosa. A common adverse reaction is digestive tract mucosal damage. Some patients have to stop taking aspirin due to severe digestive tract damage. In addition, people with asthma and those who are allergic to nonsteroidal anti-inflammatory drugs should not use aspirin.

Clopidogrel causes significantly less damage to the digestive tract than aspirin, and will not trigger or aggravate asthma. Its overall adverse reactions are less than aspirin. Therefore, people who cannot tolerate the adverse reactions of aspirin can use clopidogrel instead of aspirin after confirming that clopidogrel is effective.

In summary, although aspirin and clopidogrel have different working mechanisms, they can both effectively inhibit platelet aggregation. In terms of preventing cardiovascular and cerebrovascular diseases, the two can replace each other, and clopidogrel has fewer side effects than aspirin.

However, clopidogrel has genetic differences, and genetic testing is required when it is used, and the cost of the drug is high. Therefore, when choosing antiplatelet drugs, aspirin is usually the first choice. Only when aspirin is contraindicated or serious adverse reactions occur, clopidogrel is considered as a substitute. I am pharmacist Huazi, welcome to follow me and share more health knowledge.