Skip to main content

Lecture Notes on Antiplatelet agents

Overview of the Topics
Antiplatelet Drugs (Click Here)

Antiplatelet drugs

- Platelet aggregation occurs in response to vascular injury
- The aggregation of platelets  in the coronary artery can lead to the development of atherosclerotic plaque
- It may precipitate coronary vasospasm, myocardial infarction, and stroke

Clinical Indication
- Prophylaxis of arterial thrombosis
- Therapeutic management of myocardial infarction and stroke
- Should be infused within 2 hours of myocardial infarction or stroke for significant benefit

Clinically Important Antiplatelet Agents
- Thromboxane A2 pathway, ADP pathway & GPIIb/IIIa receptors are the therapeutic targets to prevent platelet activation and aggregation. The drugs include
- Aspirin
- Clopidogrel
- Abciximab

Aspirin

- Aspirin inhibits platelet aggregation and prolongs bleeding time 
- Aspirin irreversibly inhibits an enzyme cycloxygenase (COX-1) in platelets and prevents the formation of thromboxane A2
- In endothelial cells, aspirin inhibits the synthesis of prostacyclin (PGI2)
- The selective inhibition of thromboxane A2  inhibits platelet activation (See figure above)
- Aspirin shows drug interaction with ibuprofen, ibuprofen lowers the effect of aspirin by decreasing the availability of COX for acetylation.

Clopidogrel

-Clopidogrel and structurally related drugs irreversibly inhibit specific purinergic receptors and interfere with ADP and receptor binding
- This results in decreased ADP induced expression of platelet membrane GPIIb/IIIba and fibrinogen binding to platelets
- Often used for prevention of thrombotic stroke in patients that cannot tolerate aspirin 

Abciximab
- Chimeric monoclonal antibody Abciximab binds to the GPIIb/IIIa complex  
- inhibits the interaction of fibrinogen and von Willebrand's factor with the integrin receptor
- decreases the platelet aggregation

For more information on Antiplatelet medications visit: https://www.ncbi.nlm.nih.gov/books/NBK537062/, https://www.ncbi.nlm.nih.gov/books/NBK470539/


Labels:

Comments

Post a Comment

Popular posts from this blog

MCQs on Neisseria gonorrhoeae and Neisseria meningitidis: Medical microbiology

                                                       Multiple Choice Questions on Neisseria species (Gram-negative cocci) 1) A 19-year-old female college freshman, presented to the university health center with a severe headache, fever, and a stiff neck. She lived in a dormitory and was active in various social activities. She had received all her childhood vaccinations but had not received a booster for the meningococcal vaccine recommended before college entry. Clinical Presentation: On day 1, the patient experienced a sudden onset of fever (39.5°C or 103.1°F), severe headache, nausea, and vomiting. She also noticed a rash on her trunk and legs. Over the next two days, her symptoms deteriorated further, leading to photophobia and altered mental status. Concerned, her roommates brought her to the university health center. Physical Examinati...
4 comments
Read More

Multiple Choice Questions (MCQs) on Diabetes Mellitus: Pathogenesis, Diagnosis and Treatment

                                        MCQs on Diabetes mellitus 1) Diabetes mellitus is a disorder characterized by hyperglycemia.  Which of the following is not the common characteristic features of type 2 diabetes mellitus ? a) Impaired insulin secretion b) Increased Insulin resistance  c) Diabetic ketoacidosis d) Excessive hepatic glucose production 2) Which of the following are the characteristic features of type 1 diabetes mellitus? a) Type 1 diabetes is caused by an absolute deficiency of insulin. b) Type 1 diabetes is associated with the autoimmune destruction of beta cells.  c) Patients with  uncontrolled type 1 diabetes present with diabetic ketoacidosis d) All of the above   3) Which of the following serum measurements are not used for the diagnosis of diabetes mellitus? a) Fasting blood glucose d) Postprandial blood glucose  c) Insulin ...
6 comments
Read More

Carbohydrate Metabolism: MCQs and answers on Glycolysis & Gluconeogenesis

                                      MCQ on Glycolysis & Gluconeogenesis 1) Which of the following enzyme is not involved in galactose metabolism? a) Glucokinase b) Galactokinase c) Galactose-1-Phosphate Uridyl transferase d) UDP-Galactose 4- epimerase 2) Which of the following enzyme is defective in galactosemia (type I) - a fatal genetic disorder in infants? a) Glucokinase b) Galactokinase c) Galactose-1-Phosphate Uridyl transferase d) UDP-Galactose 4- epimerase 3) In the liver, the accumulation of which of the following metabolite attenuates the inhibitory of ATP on phosphofructokinase? a) Glucose-6-Phosphate b) Citrate c) Fructose-1,6-Bisphosphate d) Fructose-2,6-Bisphosphate 4) Mutation in which of the following enzymes leads to a glycogen storage disease known as "Tarui’s disease"? a) Glucokinase b) Phosphofructokinase c) Phosphoglucomutase d) Pyruvate Kinase 5) E...
Read More