Flashcards in Pharm 6 Thrombi pt2 Deck (32)
All antiplatelets are taken __ and reach peak concentration in how much time?
Quick (1-2 hours)
Antiplatelet drugs (aspirin) works how?
Work at the ADP receptor on cell sites on platelets or RBC.
Apparently God screwed up by not letting humans have __ naturally in their body.
Aspirin's (ASA) Mechanism of Action
Aspirin prevents conversion of arachidonic acid to prostaglandin H2
Irreversably inactivates COX (1 and 2)
Aka: Irreversibly inhibits platelet aggregation for the life of the platelet (usu. ~7-10 days)
What are the 2 COX isoforms? Whwere do they exist?
What does COX stand for?
COX-2 is an inducible enzyme increased in many settings (inflammation, infection)
Only COX-1 is in platelets (no areas of inflammation)
COX = Cyclooxygenase
What happens to you after you take One baby aspirin?
1-2 hours after swallowing, all your platelets will be irreversibly affected. You won’t clot again normally for 5-7 days. At this point you have created new platelets to return the normal clotting ability.
If aspirin must be discontinued for a procedure, how many days ahead of time do you stop?
5 days prior
Patient is takes aspirin, but must get a tooth pulled. What do you do?
don’t stop the drug. Instead, apply pressure. Procedure is too miniscule.
Patient takes aspirin, must have orthopedic joint replaced (knee/hip) after they had an MI!
What do you do?
Put off the joint replacement until later.
Patient takes aspirin and must get a Colonoscopy. What do you do?
What if you find a polyp?
Do a virtual colonoscopy with a CT (there's a risk of bleeding with a regular colonoscopy)
If I find a polyp then I’ll decide when to pull you off the drug, do the procedure, then restart the drug the next day.
___ can be measured in serum within 5-30 minutes of oral admin of Aspirin
Aspirin analogy: Railroad cars
Aspirin makes it so you can’t push those railroad cars together (prevents coupling of platelets)
Simplified dosing info for Aspirin.
usually 81 mg
Only time you use more than 81 mg is when they’re having acute MI. Then they get 325 mg.
2 issues with aspirin
What's the most consistent form of aspirin?
Resistance - Increasing the dose works
Insensitivity - Increasing dose won't help
Taking uncoated aspirin (recommended) has increased consistency over the enteric-coated aspirin.
Mechanism of action?
How long does it take to work?
Inhibits ADP-induced expression of platelet GPIIb/IIIa and fibrinogen binding to activated platelets resulting in platelet “de-coupling”
Works within 4 days, fully effective in 10 days
Antiplatelet therapy for an AMI
give aspirin to prevent platelets from clumping. Then Clopidogrel to get any platelets that still clump (or already clumped) to de-couple.
Compare how aspirin and clopidogrel work, in simple terms:
Aspirin: prevents platelet aggregation
Clopidogrel: de-couples already clumped platelets
FDA-approved indications of Cloopidogrel (6)
you want to decouple platelets for the following:
Non-ST-segment elevation ACS (unstable angina, non-Q-wave AMI)
ST-segment elevation AMI
S/P PTCA with stent
How is PAD diagnosed?
Ankle Brachial Index
List these 3 in order from Lowest bleeding risk - Highest bleeding risk
ASA 81mg, ASA 325 mg, Clopidogrel
ASA 81 mg
ASA 325 mg
If antiplatelet drugs (Clopidogrel) increase risk of bleeding where are you at highest risk to bleed?
Clopidogrel's drug interaction
Clopidogrel has variable metabolism when combined with some PPI's
Thrombolytics are ___ activators, a pre-cursor to __ which does what?
Plasmin dissolves otherwise stable and formed clots
Thrombolytic drugs convert __ to __, which in turn:
plasminogen to plasmin
lyses thrombi, fibrinogen and other plasma proteins
Thrombolytics are the drug of choice to break down newly formbed thrombi.
When are they most effective? (duh)
How long can they be used?
Most effective immediately after thrombosis
Can be used up to 6 hours after onset of symptoms
When are thrombolytics truly used?
Thrombolytics are only used when you can’t get to a Cath lab in time.
Why are thrombolytics the most dangerous of all the drugs in this powerpoint?
Break up/bust clots. Do so indiscriminately. Any clot in the body will be lysed.
The ambulance bumps around and it takes multiple tries and there’s plenty of incisions from the needles. You get to the hospital and get poked with more needles. Then you get the thrombolytic and you’d bleed like a pig.
1st Generation thrombolytic/fibrinolytic
Who gets it?
Streptokinase - a non-enzymatic protein derived from beta-hemolytic streptococcus indirectly activates plasminogen
Unique CI: Recent Strep Throat. They’ll go into anaphylaxis & probably die.
Older patients (>70) get Streptokinase.
FDA approved use for thrombolytics
When can you not give thrombolytics?
ST-segment elevation MI
If the patient does not have ST elevation, they CANNOT get thrombolytics.
Multiple CI of Thrombolytics (8)
recent hemorrhagic CVA, recent surgery (especially ocular/brain surgery), CPR > 10 minutes, AAA, uncontrolled HTN, some malignancies, non-compressible arterial punctures, etc
What do you give if thrombolytics cause bleeding, or are overdosed?
Antifibrinolytic drugs and Fresh Frozen Plasma