Antiplatelet Drugs - Uses, Dosage, Precautions, And Interactions.

What Are Antiplatelet Drugs?

Antiplatelet drugs are commonly known as blood thinners that help to prevent or break up dangerous blood clots from forming in the blood vessels or heart. The antiplatelet drugs make platelets less sticky and also inhibit clot formation. These drugs are divided into oral and parenteral agents. Aspirin was the first antiplatelet drug and is a cyclooxygenase inhibitor. The oral agents are subdivided on the basis of their mechanism of action.

What Are the Uses of Antiplatelets?

Antiplatelets are most commonly prescribed in people with the following medical conditions:

• People who have a history of heart attack or warning signs of a possible heart attack in the future.

• It is prescribed in people with unstable angina, acute coronary syndrome, or those who have received a stent during percutaneous coronary intervention.

• Antiplatelets are used to prevent stroke or transient ischemic attacks.

• The drug is recommended for people who are undergoing angioplasty with or without stenting. It prevents clots from forming inside the stents.

• Antiplatelets are the second choice for primary as well as secondary prevention of heart diseases in people allergic to aspirin or who cannot tolerate aspirin.

• Clopidogrel is mostly used in place of aspirin for people who have narrowing of the coronary arteries or have stents inserted.

• The drug is also used after heart bypass or valve replacement surgery.

• Antiplatelets are used after bypass graft surgery that uses a man-made graft performed on the arteries below the knee.

How Do Antiplatelets Work?

Antiplatelets are classified based on the mechanism of action -

1. Platelet aggregation inhibitors such as Aspirin and related cyclooxygenase inhibitors work by irreversibly inhibiting the cyclooxygenase enzyme (COX) activity in the prostaglandin's synthetic pathways and blocking the formation of thromboxane.

2. Oral thienopyridines such as Clopidogrel, Ticagrelor, Ticlopidine, and Prasugrel selectively inhibit adenosine diphosphate-induced (ADP) platelet aggregation.

3. Glycoprotein platelet inhibitors such as Abciximab, Eptifibatide, and Tirofiban. These work by inhibiting glycoprotein receptors on platelets and decreasing platelet aggregation and are used for short-term therapy.

4. Dipyridamole has vasodilating properties and inhibits the platelet cyclic nucleotide phosphodiesterase. They block the uptake of adenosine by the platelets, which also increases cyclic AMP.

5. Cilostazol acts by reducing the smooth muscle cell hyperproliferation and initial hyperplasia after an injury to the endothelium.

How Are Antiplatelets Taken?

Antiplatelets can be administered by oral, rectal, or intravenous routes. They should not be taken on an empty stomach. They are available in different strengths and come in pill form. The medicines can be taken with or without food and are taken once a day, simultaneously each day. The concomitant use of Omeprazole and Esomeprazole should be avoided while taking antiplatelets

What Is the Dosage of Antiplatelets?

Missed Dose:

If you forget to take a dose of antiplatelets, it is advised to take it as soon as you remember. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take double the dose as it may increase the risk of side effects.

Can We Use Antiplatelets and Anticoagulants Together?

Yes. The combination of anticoagulants and antiplatelet therapy is more effective than antiplatelets alone for the initial and long-term management of acute coronary syndromes. However, it increases the risk of bleeding.

Overdose:

Taking more than 150 mg/kg of body weight of antiplatelets can be life-threatening and sometimes fatal. The patients will need monitoring for signs and symptoms of bleeding and the development of metabolic derangements like acidosis.

What Precautions Should Be Taken When Taking Antiplatelets?

• Pregnancy and Breastfeeding - Antiplatelets should be taken with caution during the last two weeks of pregnancy as they may cause bleeding problems in the baby or mother before and after delivery. The drug passes through the breast milk and should be administered as prescribed by the doctor.

• Hypersensitivity - Allergic reactions can occur with the blood thinners and may cause severe reactions, itching, urticaria, and skin rashes.

• Liver Disease - Acute and chronic liver diseases can complicate heart conditions and is contraindicated in decompensated liver cirrhosis.

• Asthma - Aspirin can cause bronchospasm and worsen pre-existing asthma and increase the risk of nasal polyps and rhinitis.

• Peptic Ulcer Disease - Aspirin inhibits COX-1 activity in the gastric mucosa by suppressing the synthesis of protective prostaglandins and developing gastrointestinal ulcers and other complications.

• Uncontrolled Hypertension - Antiplatelets should be administered with caution in patients with severe hypertension over 299/110 mmHg. Clopidogrel is not recommended in the primary prevention of cardiovascular events in patients with hypertension.

• Large esophageal Varices - These drugs can cause stomach ulcers and internal bleeding and should be avoided.

• Children - Clopidogrel should not be given to children under 16 years of age unless advised.

• Bleeding Disorder - Antiplatelets increase the risk of bleeding and interfere with the blood’s clotting action and should be avoided in hemophilia.

• Geriatrics - Seniors have a higher risk of bleeding from certain antiplatelets and should be given with caution.

• Kidney Diseases - Antiplatelets may increase the tendency to bleed in people with kidney diseases.

What Are the Side Effects of Antiplatelets?

Common side effects of Antiplatelets are

• Headaches.

• Nausea.

• Diarrhea.

• Stomach ache.

• Nosebleed.

• Indigestion.

• Dizziness.

• Flushing.

• Back pain.

Serious side effects include

• Rashes and itching.

• Severe stomach ache.

• Uncontrolled bleeding or unusual bruising.

• Vomiting with blood.

• Weakness or numbness in arms and legs.

• Blood in the urine.

• Blood in stools.

• Breathing problems.

• Swelling in lips, mouth, or throat.

What Are the Interactions of Antiplatelets?

Drug Interactions:

Antiplatelets can interact with other medications such as

• Lithium.

• Methotrexate.

• Blood thinners.

• Diuretics.

• Antidepressants.

• Phenytoin.

• Cyclosporine.

• dichlorphenamide.

• Mifepristone.

• Corticosteroids such as prednisolone.

• NSAIDSs like ibuprofen, ketorolac.

Interaction with Food:

• Grapefruit - Grapefruit juice while taking Clopidogrel is not advisable as it can decrease the effects of the antiplatelet.

• Cranberry - Cranberry juice and other cranberry products can alter the effects of anticoagulants.

• Vitamin K - In addition, It is advised to avoid vitamin K-rich foods and beverages like-

beef liver, broccoli, sprouts, cabbage, cheese, collard greens, green tea, asparagus, and kale.

Conclusion:

Antiplatelets help prevents dangerous blood clots in your blood vessels or heart. These agents are given depending on the clinical situation and are prescribed with an interprofessional team approach including clinicians, specialty-trained nurses, and pharmacists. This communication is essential to minimize adverse outcomes for patients using these drugs. Always follow the instructions of your doctor when taking antiplatelet.