Platelet aggregation inhibitors: indication, list, side effects

Aspirin, Plavix®… Platelet aggregation inhibitors prevent platelets from sticking together. When are they prescribed? stroke? Heart attack? What are these medicines? What are the side effects and contraindications?

Definition: What is a platelet aggregation inhibitor?

It is a drug that is used prevents the formation of blood clots that clog the vessels. It does this by fighting platelet aggregation in the blood.

Indications: When to take a platelet aggregation inhibitor?

A platelet aggregation inhibitor prevents thromboembolic accidents (myocardial infarction, angina pectoris, stroke) and associated cardiovascular complications. Treatment is initiated after medical intervention (stenting, angioplasty, bypass) or after a recent stroke : myocardial infarction, stroke, PAD (sclerosing arteriopathy of the lower extremities), unstable angina (angina pectoris), transient ischemic attack. Patients with a high vascular risk are also candidates for this treatment. In some cases, an antiplatelet drug may be prescribed as a substitute for vitamin K antagonists (anticoagulant) if contraindicated.

How does a platelet aggregation inhibitor work?

A platelet aggregation inhibitor prevents platelet aggregation. The mechanism of action varies depending on the molecule.

► At low doses Acetylsalicylic acid (aspirin) blocks the action of platelet cyclooxygenase and thus reduces the production of thromboxane A2 (substance responsible for platelet aggregation and reduction of the caliber of blood vessels).

► At doses ≥ 500 mg/dose, this molecule occurs analgesic properties because of a different mode of action.

► Medication Plavix® and Efient® act the same way. They are converted into a product that blocks ADP binding (chemical substance) to its P2Y12 receptor, which is found on the blood platelets. The drug Brilique® is directly active by binding to the P2Y12 receptor. However, it does not prevent ADP fixation blocks the transmission of the signal to its receiver.
► Also persantine® (Dipyridamole) blocks ADP production and increases blood flow in the coronary arteries (arteries that supply the heart).
► Finally, ticlopidine prevents fibrinogen binding to its platelet receptor. Fibrinogen is a protein produced by the liver that plays a role in stopping bleeding.

What is the list of top antiplatelet drugs in France?

The main antiplatelet drugs marketed in France are:

  • acetylsalicylic acid : Acetylsalicylic acid Mylan, Aspirin Protect®, Kardegic® and Resitune®.
  • clopidogrel : Plavix® and generics
  • ticagrelor : Brilique®
  • The Prasugrel: Efient® and generics
  • dipyridamole : Persantines®
  • ticlopidine : Ticlopidine EG, Ticlopidine Arrow. The original drug Ticlid® is no longer marketed.

The commercial specialty Duoplavin® contains a Combination of acetylsalicylic acid and clopidogrel. Several generics are also available. The administration of Brilique® or Efient® is always coupled with acetylsalicylic acid. The choice of molecule depends on the nature of the vascular accident and the desired preventive effect.

What are the side effects of platelet aggregation inhibitors?

All platelet aggregation inhibitors can be responsible for this bleeding which are characterized in particular by bleeding nose, gums, stomach and intestines. Likewise, headache and indigestion observed, with the exception of Efient®. Digestive disorders include diarrhea, constipation, abdominal pain, ulcers or inflammation of the lining of the stomach, and intestinal disorders. Adverse effects that have been reported with acetylsalicylic acid are skin damage (urticaria, skin rash), a increased liver enzymes, a transient kidney failure and the onset of a gout attack in predisposed individuals. The intensity and occurrence of digestive disorders are dose-dependent. A Kidney damage and hematoma have been reported with Plavix® (clopidogrel). The most common side effects of Brilique® are: Dizziness, loss of consciousness, hypotension and gout attacks. The appearance of a Anemia, bruising, blood in the urine and rash is possible with Efient®. In addition, Persantine® (Dipyridamole) can cause Dizziness, angina pectoris, palpitations, skin rash associated with hives and muscle pain. Regarding ticlopidine-based drugs, they can cause Decrease or absence of white blood cellsRash, dizziness, increased liver enzymes, cholesterol and triglycerides.

What are the contraindications of antiplatelet drugs?

Acetylsalicylic acid (aspirin) is contraindicated in many situations:

  • Disease caused by a nonsteroidal anti-inflammatory drug (including aspirin): asthma or history of asthma, history of digestive disorders (ulcer, bleeding, perforation)
  • progressive stomach ulcers
  • Hemorrhagic disease or risk of bleeding.
  • Severe heart, liver or kidney failure
  • mastocytosis (Collection of a certain type of immune cells found particularly in the skin and bone marrow). In this case, the drug promotes the occurrence of severe allergic reactions.

This drug is not contraindicated in pregnant women in low doses (anti-platelet aggregation dose). On the other hand, this is the case at analgesic or anti-inflammatory doses (≥ 500 mg per dose). formally prohibited from the 6th month of pregnancy.
► Plavix® (clopidogrel) should not be taken in severe hepatic insufficiency and progressive diseases (intracranial haemorrhage, gastric ulcer).
► The drug Efient® (Prasugrel) should not be administered bleeding in severe hepatic insufficiency related to an illness or a history of stroke or a transient ischemic attack.
► Brilique® (ticagrelor) is strictly contraindicated in Severe hepatic impairment, disease-related bleeding or history of intracranial haemorrhage. In addition, it should not be combined with certain drugs such as ketoconazole (fungal treatment), clarithromycin (antibiotic), ritonavir (antiviral).
► Ticlopidine should be avoided if necessary Stomach ulcer, recent stroke, certain blood disorders or lack or absence of white blood cells.
► The specialty Persantine® (dipyridamole) should not be taken fructose intolerant patientshave glucose or galactose malabsorption syndrome or have a deficiency of enzymes that allow sugars to be digested.

Blood in the stool or urine, bleeding gums, abnormal tiredness, or paleness of the face should prompt the patient to see a doctor

Is it compatible with anticoagulants?

Due to the increased risk of bleeding The combination of an antiplatelet agent and an anticoagulant (oral or injectable) is not recommended. It is not even recommended for patients with gastric or duodenal ulcers. However, certain medical situations require the simultaneous administration of the two drugs. This applies in particular to Dipyridamole in combination with an oral anticoagulant in a patient with a prosthetic heart valve. If an antiplatelet agent is prescribed along with an anticoagulant, the occurrence of bleeding should be monitored. In fact, hemorrhagic signs such as the presence of Blood in the stool or urine, bleeding gums, abnormal tiredness, or pale face should prompt the patient to seek medical attention see a doctor as soon as possible.

Sources:
– Public drug database. ANSM
– Antiplatelets, Pharmacomédicale.org

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