Monica - Week 4 - Exam 2 Flashcards
what are the vitamin K dependent clotting factors?
factors 2, 7, 9, 10
what factors does Heparin stop?
stops 10a and 2a (prothrombin) - powerful, able to stop 2 clotting factors - not allowing fibrin to form
what factors does Lovenox stop?
stops 10a - prevents the rest of the cascade (final common pathway)
T/F Heparin and Lovenox break down clots.
FALSE. they prevent clots from forming and prevent already existing clots from becoming bigger
what is heparin (unfractionated) derived from?
derived from mucosal tisssues of animals (pigs and cattle) → pig intestine has natural occurring polysaccharide → anticoagulant
what does heparin inhibit?
inhibits the activity of several blood coagulation factors
how is enoxaparin obtained?
obtained through cleaving of heparin into smaller fragments; similar to heparin, but has shorter polysaccharide chains
because of the shorter polysaccharide chains, this makes it a _____ _______ ________.
lower molecular heparin - low-molecular weight heparin (LMWH)
when is heparin/lovenox contraindicated?
- if the patient has a pig/cattle allergy
- religious belief not to eat pig or cattle
what are 3 main characteristics of antithrombin?
- natural anti-coagulation
- inhibits thrombin (factor 2)
- prevents conversion of fibrinogen to fibrin (keeps us from making unnecessary clots)
antithrombin binds to ______ and _______
heparin and enoxaparin
the combination of antithrombin and heparin inhibits which two factors? what does this cause?
inhibits factors 10a and 2a - more potent complex
the combination of antithrombin and enoxaparin inhibits which factor? what does this cause?
inhibits factor 10a - less potent effect
what are the 3 indications for the use of heparin?
- prophylaxis and tx of thromboembolic events
- prevents enlargement of existing clots
- prevents formation of new clots
when is heparin commonly used?
post ortho and GI surgeries
for prophylaxis, what is the normal route/dose for heparin? other characteristics?
- SubQ
- given q 8 - 12 hrs
- usually 5000 units
- *used in bridge therapy; 1-3 days before warfarin works
- *no monitoring needed
although no monitoring is needed for prophylactic heparin, what labs are good to look at?
platelets - looking for thrombocytopenia
for an already existing clot, what is given?
therapeutic heparin therapy
for therapeutic heparin therapy, what is dosing?
- intermittent or continuous IV infusion
- weight based dosing
what does the weight based dosing also take into account? who does this?
pharmacy is in charge of dosing; also take into account type of clot, risk factors, diagnosis, and weight
what kind of dose is given prior to therapy? why?
a bolus dose is given first; helps pt achieve ↑ therapeutic level
what labs are taken into account and have to be monitored?
aPTT requires monitoring
↑ therapeutic aPTT level
what are 2 ways to best describe aPTT?
- used in heparin monitoring - how pharmacy knows to ↑/↓ a dose or to hold it
- measures the time (seconds) for a clot to form
what is the control range of PTT?
25 - 35 seconds
what is the therapeutic range of PTT?
30 - 80 seconds
what is therapeutic range dependent on?
dependent on how the clot was acquired, risk factors, past medical history, what the risk of the clot is
for intermittent infusion, when is aPTT drawn?
aPTT drawn 30 min before dose during initial therapy and then periodically
for continuous infusion, when is aPTT drawn?
aPTT monitored q4-6hr during early therapy
- if critically high → stop heparin for 1 hr and redraw aPTT and call pharmacy
What is HIT?
heparin induced thrombocytopenia
- Not common, adverse effect
- Occurs in 5% of patients on heparin
What is heparin induced thrombocytopenia characterized by?
- Platelet drop by 50% from baseline
What is the process map of thrombocytopenia?
- Platelet-factor-4 (PF-4) releases (no known function)
- PF4 binds to heparin and creates a complex
- Complex goes into circulation
- Platelets are activated + release PF4 (ongoing loop)
- Thrombus is formed
- Antibody response
- Thrombocytopenia (autoimmune response)
What is enoxaparin indicated for? How does it work?
- Indicated for VTE phophylaxis or treatment of DVT/PE
- **hip/knee/GI surgery; possible MI in past
- Inhibits factor 10a
What labs are monitored for prophylaxis lovenox?
No routine lab monitoring
T/F: lovenox has a longer duration than heparin
TRUE; going given 1 - 2/day
What should be assessed when giving lovenox?
thrombocytopenia and bleeding
What teaching would go along with lovenox?
teaching pts how to give injections at home
What is the normal order for lovenox for prophylaxis?
30-40mg daily or q12hr
What is the normal order for coagulation treatment lovenox?
Weight based dose (1mg/kg q12hr or 1.5mg/kg q24hr)
What is the anecdote for heparin?
Protamine sulfate IV
- Inactivates heparin and lovenox; onset 30 sec – 1 min
What are the 7 NI for anticoagulant therapy?
- Never use heparin and lovenox concurrently
- Assess for signs of bleeding (nose, gums, stool, urine)
- Contraindicated w/ hemorrhagic stroke or uncontrolled HTN
- Monitor platelet count for thrombocytopenia
- Stop medication w/ signs of bleeding
- D-D interactions – warfarin, NSAIDS can ↑ bleeding
- Herbal products ↑ risk of bleeding (green tea, ginger, gingko, garlic
