HEMATOLOGY - anticoagulant, antiplatelet & thrombolytic drugs Flashcards
EXAM 2 content
what is a thrombus?
stationary clot attached to the vessel wall or within the heart
what is an arterial thrombi? what kind of drugs do they respond well to?
they form under conditions of high blood flow
- composed of plate aggregates held by fibrin strands
- responds well to antiplatelet drugs
what is a venous thrombi? what kind of drugs do they respond well to?
forms under conditions of low blood flow
- composed of RBCs w/ large amounts of fibrin, few platelets
- responds well to anticoagulant drugs
if the body has a thrombus, what will the body naturally do to it?
if body has a thrombus it will reduce through plasmin (enzyme that degrades fibrin meshwork of clot) & breaks it down over time
OR
what happens if the body can’t break down the clot?
- will obstruct blood flow to tissues or organs –> depriving them of essential nutrients
OR - will become an embolus – when a thrombus detaches from the vessel wall & circulates in bloodstream –> life threatening depending on site of occlusion
what 3 classes of drugs do providers prescribe if a pt has increased coagulation, clotting, clumping? what does each class of drug most effective for? what do all 3 have an increase risk for?
- anticoagulant drugs: disrupts coagulation cascade + suppresses production of fibrin (does NOT dissolve clots) – best for venous & atrial thrombosis
- antiplatelets drugs: inhibits platelet aggregation (clumping) – best for preventing arterial thrombosis
- thrombolytic drugs: promotes lysis of fibrin + dissolves thrombi & newly formed thrombi (only drug that dissolves clots)
all increase risk of bleeding
what drugs are under anticoagulants?
- UNFRACTIONATED HEPARIN
- LOW MOLECULAR WEIGHT (LMW) HEPARIN
- FONDAPARINUX
- VITAMIN K ANTAGONIST
what is the mechanism of action of heparin & its derivatives
activates antithrombin
- enhances antithrombin: protein that inactivates thrombin & factor Xa (major clotting factors) –> production of fibrin is reduced, clotting suppressed
what are the adverse effects of UNFRACTIONATED HEPARIN?
all bleeding related
- hemorrhage
- spinal/epidural hematoma
- heparin induced thrombocytopenia
- hypersensitivity
what are the warnings of UNFRACTIONATED HEPARIN?
use with caution in patients with bleeding risk
what are the contraindications of UNFRACTIONATED HEPARIN (UH)?
- thrombocytopenia (<50,000)
- uncontrolled bleeding
- lumbar puncture, regional anesthesia
what are the different types of indications since dosing varies with UNFRACTIONATED HEPARIN? which types of tests requires or doesn’t require monitoring?
- prevention: 5,000 units q 8-12 hours – aPTT monitoring is NOT required
- treatment: continuous IV infusion – aPTT monitoring IS required
why is aPPT monitoring not required for prevention type of treatmemt?
bc the dose is small & heparin has a short half life
what do we use if a pt overdoses on heparin? how do we administrate it?
PROTAMINE SULFATE – antidote
- slow IV injection
what are the two tests used to monitor the effectiveness of UNFRACTIONATED HEPARIN (UH)?
- activated partial thromboplastin time (aPTT, most common)
- anti factor Xa heparin assay
what is the normal value of aPPT? therapeutic levels? how often do we measure?
- normal value = 40 seconds
- therapeutic levels = increases 1.5-2x more –> 60-80 secs
- measure q4-6 hours during initial phase of therapy
- effective dosage established = measure daily
what does anti factor xa heparin assay measure? what levels indicate UH is therapeutic? what is so good ab this test?
- measures heparin & its activity
- antithrombin binding to Xa is increased
- therapeutic range = 0.3-0.7 IU/mL
- great bc its more accurate than aPPT but more expensive
what is the exemplar drug for LMW heparin? how are they different from UH?
ENOXAPARIN (LOVENOX)
- other: Dalteparin (Fragmin)
- has molecules that are shorter than UH
what are the therapeutic uses of ENOXAPARIN (LMW)?
- prevention of DVT after surgery (abd, hip + knee replacement)
- treatment of established DVT, w/ or w/o PE
- prevention of ischemic complications (unstable angina, non Q wave MI, STEMI)
what are the adverse effects of ENOXAPARIN (LMW)?
- bleeding (always)
- severe neurologic injury with pts undergoing: spinal puncture, spinal or epidural anesthesia
what are the contraindications/precautions of ENOXAPARIN (LMW)?
- serious harm increased by concurrent use of ANTIPLATELET drug or ANTICOAGULANT
- if overdose –> PROTAMINE SULFATE
how are we administering ENOXAPARIN (LMW)? how do we determine the dose?
SQ – daily or twice a day
- dose is based on: indication, weight & renal function –> can be used at home but expensive
how do we know if ENOXAPARIN (LMW) has been effective?
does not require routine coagulation monitoring –> more tolerable + decr cost of lab monitoring