Heme/onc Flashcards
Activator of antithrombin;thrombin and factor Xa. Short half-life.
Heparin
Uses of Heparin?
MOA?
Immediate anticoagulation for pulmonary embolism (PE), acute coronary syndrome, MI, deepvenous thrombosis (DVT). Used during pregnancy (does not cross placenta).
Follow PTT.
MOA: activator of antithrombin: decrease thromibn and factor Xa activity
Pt comes in with DIC.. you provide a medication that acts as a cofactor for antithrombin.
BAD shits starts happening!!!
what (-) rxns does this drug cause?
How do we undo the damage??
Bleeding, thrombocytopenia (HIT), osteoporosis, drug-drug interactions.
For rapid reversal (antidote), use protamine sulfate (positively charged molecule that binds negatively charged heparin).
Wht are examples of Low molecular wt Heparins?
What are their benifits?
Enoxaparin, Dalteparin, while fondaparinux act more on f_actor Xa_, have better bioavailability, and 2–4 times longer half-life; can be a_dministered subcutaneousl_y and without laboratory monitoring.
(-)Not easily reversible.
Most severe rxn to Heparin and what’s its mechanism?
Heparin-induced thrombocytopenia (HIT)—development of IgG antibodies against heparin- bound platelet factor 4 (PF4).
Antibody-heparin-PF4 complex a_ctivates platelets–> thrombosis and thrombocytopenia._
What is the mechanis of Argatroban and Bivalrudin?
from leeeeches!
INHIBIT thrombin DIRECTLY; used instead of heparin for antigoag in pts w/ HIT
All ya know about Heparin
Large, anionic
Parenteral (IV, SC) admin
rapid actication
activates antithrombin to decrease IIa and factor Xa
Lasts hours, safe for preggers
reveresed with protamine sulfate
moniotor PTT
All ya know about warfarin
Small-lipid monlecues
Oral admin
acts in liver
slow, limited by 1/2 lives of normal clot factors
Impair synthesis of Vit K: diSCo in 1927
Chroinc duration
Crosses placenta (tereatogenic)
OD use IV vit K or FFP
monitor with IRN and PT (extrnisic pathway)
Interferes with γ-carboxylation of vitamin K– dependent clotting factors II, VII, IX, and X, and proteins C and S.
Warfarin
Why do some people respod to Warfarin differently?
Metabolism affected by polymorphisms in the gene for vitamin K epoxide reductase complex (VKORC1). In laboratory assay, has effect on EXtrinsic pathway and incase PT. Long half-life.
Use of Warfarin
How do we monitor it?
Chronic anticoagulation (e.g., venous thromboembolism prophylaxis, and prevention of stroke in atrial fibrillation).
Not used in pregnant women (because warfarin, unlike heparin, crosses placenta).
Follow PT/INR
What toxicities do we worry about in warfarin?
What is the pathology of bleeding we see?
Bleeding, teratogenic, skin/tissue necrosis
A , drug-drug interactions. Proteins C and S have shorter half-lives than clotting factors
II, VI, IX, and X, resulting in early transient hypercoagulability with warfarin use.
Skin/tissue necrosis believed to be due to small vessel microthromboses.
How do you use heparin and warfarin together?
For reversal of warfarin, give vitamin K.
For rapid reversal, give fresh frozen plasma. Heparin “bridging”: heparin frequently used
when starting warfarin. Heparin’s activation of antithrombin enables anticoagulation during initial, transient hypercoagulable state caused by warfarin. Initial heparin therapy reduces risk of recurrent venous thromboembolism and skin/tissue necrosis
Apixaban, rivaroxaban: what is their mechanism and use?
bind directly to Xa
Treatment and prophylaxis for DVT and PE (rivaroxaban); stroke prophylaxis in patients with atrial fibrillation.
Oral agents do not usually require coagulation monitoring.
(-) bleeding with NO reversible agent
What is the MOA of Alteplase (tPA), reteplase (rPA), streptokinase, tenecteplase (TNK-tPA). Use?
Directly or indirectly aid conversion of plasminogen to plasmin, which cleaves thrombin and fibrin clots.
Increase PT, Increase PTT, no change in platelet count.
Use: Early MI, early ischemic stroke, direct thrombolysis of severe PE.
What pts should NOT recieve Thrombolytics: Alteplase, retelpase (tpA or rPa?
How do you tx toxicity?
Bleeding. Contraindicated in patients with active bleeding, history of intracranial bleeding, recent surgery, known bleeding diatheses, or severe hypertension.
Treat toxicity with aminocaproic acid, an inhibitor of fibrinolysis.
Fresh frozen plasma and cryoprecipitate can also be used to correct factor deficiencies.
Irreversibly inhibits cyclooxygenase (both COX-1 and COX-2) enzyme by covalent acetylation.
Platelets cannot synthesize new enzyme, so effect lasts until new platelets are produced: bleeding time,TXA2 and prostaglandins. No effect on PT or PTT.
Aspirin
Neg sides of Aspirin
Gastric ulceration, tinnitus (CN VIII).
Chronic use can lead to acute renal failure, interstitial nephritis, and upper GI bleeding. Reye syndrome in children with viral infection.
What do we see in Asprin OD?
Overdose initially causes hyperventilation and respiratory alkalosis, but transitions to mixed metabolic acidosis–respiratory alkalosis.
What type of drugs are: Clopidogrel, prasugrel, ticagrelor (reversible), ticlopidine.
MOA?
ADP recepotr inhibitors
When do we use ADP Receptor inhibitors (lopidogrel, prasugrel, ticagrelor (reversible), ticlopidine )
What is their toxicity?
Acute coronary syndrome; coronary stenting. Decrease incidence or recurrence of thrombotic stroke.
Neutropenia (ticlopidine). TTP may be seen.
What is the MOA of Cilostazol and dipyrimadole?
Uses?
Toxicity?
Phosphodiesterase III inhibitor;cAMP in platelets, resulting in inhibition of platelet aggregation; vasodilators.
Use: Intermittent claudication, coronary vasodilation, prevention of stroke or TIAs (combined with aspirin), angina prophylaxis.
Toxicity: Nausea, headache, facial flushing, hypotension, abdominal pain.
Bind to the glycoprotein receptor IIb/IIIa on activated platelets, preventing aggregation Use:Unstable angina
Abciximab, eptifibatide, tirofiban.
Cell cycle review