2. Fibrinolytics Flashcards
ASA is an effective treatment across the entire spectrum of ACS. (T/F)
True
What is the goal of ASA therapy in ACS?
quickly block formation of TXA2 in platelets
What is the effective acute dose of ASA?
160 - 325 mg
Why is the low dose ASA (81mg) ineffective in ACS?
takes several days to achieve full antiplatelet effect
Why is the ASA chewed in ACS?
buccal and sublingual absorption rather than GI
What is the ACS general treatment acronym and what does it stand for?
O: oxygen
M: morphine
N: nitroglycerin
A: antiplatelet
Why is pain management an important element of ACS treatment?
pain leads to increased SNS activity which increases the heart rate and leads to more ischemia
What analgesic agents are used with AMI?
- morphine
- Meperidine
- Pentazocine
What is the analgesic agent of choice with ACS?
morphine
Why is morphine the agent of choice for ACS?
it has venodilatory effects that reduce ventricular preload
What organic nitrate agent is indicated in most ACS?
sublingual nitroglycerin - patient must be conscience
Why are organic nitrates indicated in ACS?
- enhances cardiac blood flow by coronary vasodilation
- decreases ventricular preload
What patients are contraindicated for sublingual NG?
- hypotension (SBP < 90)
- especially accompanied by bradycardia
After administering sublingual NG, what should be monitored?
BP
What is the goal of using beta-blockers in ACS?
reducing infarct size
Which AMI patients are most suited for beta-blocker therapy?
sinus tachycardia and HTN
Why are AMI patients who have sinus tachycardia and HTN suitable for BB therapy?
- BBs lower HR and BP
- reduce myocardial O2 demand
What AMI patients are contraindicated for BB therapy?
- HF
- Hypotension/bradycardia
What BB agent is preferred in ACS and why?
metoprolol because it is cardio-selective
What is the goal of therapy for using fibrinolytics in ACS?
remove unwanted fibrin thrombi
What stimulates the endothelium to release t-PA?
reduced flow when thrombi occlude vessels
Released t-PA has a relatively long half-life. (T/F)
False: rapidly cleared from blood or inhibited by plasminogen activator inhibitors
Plasmin that leaves the clot is inhibited by what?
alpha 2-antiplasmin
Describe the t-PA 90 minute administration
- 15 mg IV bolus
- 0.75 mg/kg (50 mg max) over 30 minutes
- 0.5 mg/kg (35 mg max) over 60 minutes
t-PA is rapidly deactivated; why do we administer it?
Pharmacological administration of plasminogen activators overwhelms the inhibition
What is the first generation fibrinolytic agent?
streptokinase
What produces streptokinase?
beta-hemolytic streptococci
Streptokinase has high intrinsic enzymatic activity. (T/F)
False: no intrinsic enzymatic activity
Streptokinase forms a stable, non-covalent 1:1 complex with what?
plasminogen
Streptokinase is not fibrin specific. (T/F)
True
What is the MOA of streptokinase?
Complexes with plasminogen to expose active sight and cleave into plasmin which goes on to degrade fibrin.
Why can streptokinase administration not be repeated?
antibodies develop after treatment
What is the second generation fibrinolytic agent?
rt-PA : alteplase
What is the key fibrinolytic feature of ateplase?
prolonged plasma clearance
What are the third generation fibrinolytic agents?
- derivatives of t-PA
- rPA : reteplase
- TNK-t-PA : tenecteplase
Reteplase lacks domains that increase elimination by the _______.
liver
Reteplase has a ______ affinity for fibrin than t-PA.
lower
Why is reteplase thought to be more effective than t-PA?
it is hypothesized that it can penetrate the clot and “chew it up” from the inside
Why is tenecteplase thought to be more effective than t-PA?
It is 80x more resistant to plasminogen activator inhibitor-1 than t-PA.
How is tenecteplase dosed?
single IV bolus (weight based) over 5 seconds
Tenecteplase is more fibrin-specific than t-PA. (T/F)
True
What is anistreplase?
complex of protein bound streptokinase
What is the thrombolytic activity of anistreplase?
release of the streptokinase component
