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Questions and Answers
What is the primary effect of phosphodiesterase inhibitors on cyclic AMP levels?
What is the primary effect of phosphodiesterase inhibitors on cyclic AMP levels?
- They prevent the degradation of cAMP, increasing its levels. (correct)
- They convert cAMP to AMP, enhancing platelet activation.
- They block all calcium-mediated signaling pathways.
- They decrease cAMP levels, increasing platelet aggregation.
What mechanism is primarily responsible for the inhibition of platelet activity by cAMP?
What mechanism is primarily responsible for the inhibition of platelet activity by cAMP?
- Sequestration of cytosolic Ca2+. (correct)
- Increased Ca2+ absorption.
- Direct inhibition of thrombin.
- Activation of ADP receptors.
Which of the following is a recommended approach for using Dipyridamole in therapy?
Which of the following is a recommended approach for using Dipyridamole in therapy?
- Use it in combination with warfarin. (correct)
- Combine it with aspirin for maximum efficacy.
- Administer it alone for immediate antiplatelet effect.
- Apply it as a monotherapy in acute ischemic events.
What kind of receptor does Vorapaxar act on as a PAR-1 antagonist?
What kind of receptor does Vorapaxar act on as a PAR-1 antagonist?
What kind of adverse effect is associated with the use of Dipyridamole?
What kind of adverse effect is associated with the use of Dipyridamole?
What correlation has been observed regarding platelet function testing and antiplatelet therapy?
What correlation has been observed regarding platelet function testing and antiplatelet therapy?
Which of the following represents a limitation of tailoring antiplatelet therapy based on platelet response?
Which of the following represents a limitation of tailoring antiplatelet therapy based on platelet response?
What is the main therapeutic action of phosphodiesterase inhibitors in the context of platelet aggregation?
What is the main therapeutic action of phosphodiesterase inhibitors in the context of platelet aggregation?
What is a common characteristic of GPIIb/IIIa antagonists?
What is a common characteristic of GPIIb/IIIa antagonists?
Which of the following is a disadvantage of GPIIb/IIIa antagonists?
Which of the following is a disadvantage of GPIIb/IIIa antagonists?
What is the mechanism of action of abciximab?
What is the mechanism of action of abciximab?
Which of the following is NOT a common GPIIb/IIIa antagonist?
Which of the following is NOT a common GPIIb/IIIa antagonist?
Which patient population is most likely to benefit from ADP antagonists like Clopidogrel?
Which patient population is most likely to benefit from ADP antagonists like Clopidogrel?
What is a potential adverse effect of using abciximab?
What is a potential adverse effect of using abciximab?
What is the primary mechanism of action of Clopidogrel?
What is the primary mechanism of action of Clopidogrel?
Which statement regarding phosphodiesterase inhibitors (PDEI) is true?
Which statement regarding phosphodiesterase inhibitors (PDEI) is true?
How is Clopidogrel metabolized to its active form?
How is Clopidogrel metabolized to its active form?
What limitation is associated with the immunogenicity of abciximab?
What limitation is associated with the immunogenicity of abciximab?
How do GPIIb/IIIa antagonists primarily affect platelet function?
How do GPIIb/IIIa antagonists primarily affect platelet function?
Which factor can lead to resistance to Clopidogrel therapy?
Which factor can lead to resistance to Clopidogrel therapy?
Which of the following is a common side effect of antiplatelet therapy, including Clopidogrel?
Which of the following is a common side effect of antiplatelet therapy, including Clopidogrel?
What class of drugs does Prasugrel belong to?
What class of drugs does Prasugrel belong to?
Which statement is true regarding the activation of Clopidogrel?
Which statement is true regarding the activation of Clopidogrel?
Which subtype of ADP receptors is primarily targeted by Ticagrelor?
Which subtype of ADP receptors is primarily targeted by Ticagrelor?
Study Notes
Phosphodiesterase Inhibitors
- Phosphodiesterase inhibitors (PDEIs) prevent the degradation of cyclic adenosine monophosphate (cAMP) leading to increased cAMP levels.
- Increased cAMP levels inhibit platelet activity, reducing platelet aggregation and clot formation.
- This action is independent of the agonist, resulting in broad-spectrum inhibition.
- cAMP opposes the effects of calcium ions (Ca2+) by sequestering it.
- Dipyridamole (Persantine®) is a phosphodiesterase inhibitor that increases cAMP levels, inhibiting platelet activity.
- Dipyridamole is recommended for use in combination with warfarin.
- It can cause coronary vasodilation as an adverse drug reaction (ADR).
ADP Antagonists
- ADP receptor activation triggers platelet activation and clot formation.
- ADP antagonists can therefore reduce clot formation.
- They are useful in aspirin-intolerant patients.
- ADP activates purinergic receptors, particularly the subtypes P2Y1 and P2Y12.
- Clinically used ADP antagonists include:
- Clopidogrel (Plavix®)
- Prasugrel (Effient®)
- Ticagrelor (Brilinta®)
Clopidogrel (Plavix®)
- Clopidogrel is a prodrug that requires activation via metabolism in the liver by CYP2C19 and CYP3A4 enzymes.
- It is a noncompetitive (irreversible) ADP (P2Y12) receptor antagonist.
- Patients with poor CYP2C19 metabolism may produce less of the active metabolite and experience resistance to clopidogrel's antiplatelet effects.
GPIIb/IIIa Antagonists
- GPIIb/IIIa antagonists reduce platelet activation independent of activating agonists, providing broad-spectrum inhibition.
- These antagonists are primarily used for parenteral (intravenous) administration.
- Common GPIIb/IIIa antagonists include:
- Abciximab (Reopro®): a monoclonal antibody
- Eptifibatide (Integrelin®): a synthetic cyclic peptide
- Tirofiban (Aggrastat®): a non-peptide
- Abciximab prevents fibrinogen binding to activated GPIIb/IIIa receptors, inhibiting platelet aggregation and clot formation.
Abciximab (ReoPro®)
- Abciximab is a monoclonal antibody Fab fragment that acts as an essentially irreversible antagonist of GPIIb/IIIa receptors.
- It is administered intravenously.
- Abciximab reduces the risk of restenosis but can cause bleeding as an ADR.
- It has drawbacks such as immunogenicity, limiting its administration to single doses, and requiring parenteral administration.
- Patients may develop an allergy to the drug after a single administration.
Zontivity® (Vorapaxar)
- Vorapaxar is a first-in-class approved antiplatelet medication that acts as a protease-activated receptor 1 (PAR-1) antagonist.
- It was approved on May 8, 2014.
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Description
This quiz tests your knowledge on phosphodiesterase inhibitors and ADP antagonists, focusing on their mechanisms, effects on platelet activity, and clinical applications. You'll learn about agents like Dipyridamole, their role in preventing clot formation, and their adverse effects. Perfect for students and professionals in pharmacology.
