Hematologic: Antiplatelets Flashcards
What are antiplatelet drugs are used to treat?
To prevent arterial thromboembolism-particularly in patients at risk for:
- MI
- Stroke
- Arteriosclerosis (hardening of the arteries)
Generic names of antiplatelet drugs
- aspirin
- clopidogrel
- ticlopidine
How fast are antiplatelet drugs absorbed?
very quickly
When do antiplatelet drugs reach peak concentration?
1 and 2 hours
How long does aspirin maintain its antiplatelet effect?
- Approximately 10 days
2. Or as long as platelets normally survive.
How long does clopidogrel maintain its antiplatelet effect?
5 days
Pharmacodynamics Details
Antiplatelet drugs interfere with platelet activity in different drug specific and dosage-related ways.
SEE SPECIFIC DRUGS BELOW
Pharmacodynamics Details: aspirin
Low dosages of aspirin appear to inhibit clot formation by blocking the synthesis of prostaglandin, which in turn prevents formation of the platelet-aggregating substance thromboxane A2
Pharmacodynamics Details: Clopidogrel
Inhibits platelet aggregation by inhibiting platelet-fibrinogen binding.
Pharmacodynamics Details: Ticlopidine
Inhibits the binding of fibrinogen to platelets during thefirst stage of the clotting cascade.
Pharmacotherapeutics
Antiplatelet drugs have many different uses.
What is aspirin used to treat?
Previous MI or unstable angina
Men to reduce the risk of transient
ischemic attacks (TIAs; temporary reduction in circulation to the
brain).
Why is aspirin used in patients with previous MI or unstable angina?
Reduce risk of death
Why is aspirin used in Men?
- Reduce the risk of transient ischemic attacks (TIAs)
2. TIA-temporary reduction in circulation to the brain
What is Clopidogrel used to treat?
- Hx of a recent MI, stroke, or PAD
2. Acute coronary syndromes (esp. in patients who undergo percutaneous transluminal coronary angioplasty or CABG)
Why is Clopidogrel used in patients with Hx of a recent MI, stroke, or PAD?
reduce the risk of an ischemic stroke or
vascular death
What is Ticlopidine used to treat?
- Reduce the risk of thrombotic stroke in high risk patients (TIAs)
- Patients who have already had a thrombotic stroke.
When is Ticlopidine indicated? Why?
- Should only be used in patients who have not responded to or cannot use aspirin.
- Severe adverse effects
Drug-drug interactions with antiplatelet drugs:
- NSAIDs
- heparin
- oral anticoagulants
- methotrexate
- valproicacid
- sulfinpyrazone (relieve signs and symptoms of gout)
- Antacids
ANTIPLATELETS INTERACTION RATIONALE:
NSAIDs, heparin, or oral anticoagulants
increase the risk of bleeding
ASPARIN INTERACTION RATIONALE:
methotrexate and valproicacid
increases the risk of toxicity of methotrexate and valproicacid.
ASPARIN AND TICLOPIDINE INTERACTION RATIONALE:
sulfinpyrazone (relieve signs and symptoms of gout)
reduce the effectiveness of sulfinpyrazone
TICLOPIDINE INTERACTION RATIONALE:
Antacids
reduce the plasma levels of ticlopidine
Don’t mix and match
Because guidelines haven’t been established for administering ticlopidine with heparin, oral anticoagulants, aspirin, or fibrinolytic drugs, discontinue these drugs before starting ticlopidine therapy.
