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46 Cards in this Set
- Front
- Back
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What is hemostasis?
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The physiological process by which bleeding is stopped.
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What are the two stages of hemostasis?
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1. Formation of a Platelet Plug - platelets adhere to site of vessel injury, which initiates platelet activation, which in turn leads to massive platelet aggregation.
2. Coagulation or production of fibrin. Two pathways: Intrinsic Pathway (contact activation pathway) & Extrinsic Pathway (tissue factor pathway) |
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What are the three major groups of drugs for thromboembolic disorders?
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Anticoagulants, Antiplatelets, and Thrombolytics
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What do anticoagulant drugs do?
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They reduce the formation of fibrin and disrupt the coagulation cascade (clotting factor X). They're for venous thrombosis.
There are two MOA: inhibit the synthesis of clotting factors & inhibit the activity of clotting factors. |
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What are the anticoagulant drugs?
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Unfactionated heparin, low molecular weight heparin, Warfarin
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What does Heparin do?
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Enhances antithrombin, which inhibits clotting.
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What are the two sources of heparin?
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Lungs of cattle & intestines of pigs.
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What is the differences between unfractionated heparin and low molecular weight (LMW) heparin?
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Unfractionated heparin is the rapid-acting anticoagulant. Low molecular weight (LMW) heparin is composed of molecules that are shorter than unfractionated heparin, thus is slow-acting but also can be administered at home. However LMW heparin is most costly.
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What route is heparin (unfractionated and LMW) administered?
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Unfractionated heparin is administered by injection only: IV (continuous or intermittent) or subcut. Low molecular weight heparin is administered subcut only and the dosage is based on body weight.
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What are the therapeutic uses of unfractionated heparin?
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-Pregnancy
-when rapid anticoagulancy is required -Pulmonary emoblism -stroke evolving -massive DVT -open-heart surgery -renal dialysis -low-dose therapy postop -disseminated intravascular coagulation (DIC) -adjunct to thrombolytic therapy of acute MI |
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What are the adverse effects of unfractionated heparin?
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-hemorrhage
-heparin-induced thrombocytopenia (HIT) -hypersensitivity reactions |
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What are the contraindications of infractionated heparin?
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-thrombocytopenia
-uncontrollable bleeding -during/immediately after surgery of eye, brain, spinal cord |
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What is the antidote for heparin?
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Protamine sulfate
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What is the laboratory test used as an indicator for coagulation and the use of heparin?
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Activated partial thromboplastin time (aPTT); normal value is 40 seconds
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What are the therapeutic uses of low molecular weight (LMW) heparin?
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-prevention of DVT following surgery (including replacement of hip, knee)
-TX of established DVT -Prevention of ischemic complications (pts with unstable angina, non-Q wave MI, and ST-elevation MI (STEMI) |
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What are the adverse reactions of low molecular weight heparin?
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-bleeding (but less than infractionated heparin)
-immune-mediated thrombocytopenia -severe neurological injury for patients undergoing spinal puncture or spinal epidural anesthesia |
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What is the history of the origin of warfarin (Coumadin, Jantoven)?
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It was originally discovered by observing cattle ingesting clover silage and bleeding out. It is used at rat poison/rodenticides. Failed suicide attempt with a large dose brought renewed clinical interest.
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What is the clinical use of warfarin?
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-oral coagulant with delayed onset (won't be destroyed by acids)
-Vitamin K antagonist -blocks the biosynthesis of clotting factors VII, IX, X, and prothrombin |
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What are the therapeutic uses of warfarin?
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-NOT useful in emergencies because of delayed onset
-long-term prophylaxis of thrombosis (prevention of venous thrombosis and associated PE, thromboembolism in pts with prosthetic heart valves, thrombosis during atrial fibillation) |
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What monitoring treatments are used with warfarin?
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-Prothrombin time (PT), average preTx value is 12 seconds
-International normalized ratio (INR) |
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What are the adverse effects of warfarin?
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-hemorrahge (administer vitamin K for toxicity)
-fetal hemorrhage and teratogenesis from use during pregnancy -use during lactation/breastfeeding |
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What are the drug interactions of Warfarin?
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-drugs that increase anticoagulant effects
-drugs that promote bleeding -drugs that decrease anticoagulant effects -heparin -aspirin -acetaminophen |
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What are the antiplatelet drugs?
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Aspirin (ASA), Clopidogrel (Plavix), & Glocoprotein (GP) IIb/IIIa receptor antagonist "super aspirin" (abciximab, tirofiban, eptifibatide)
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What is the MOA of aspirin (ASA)?
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It suppresses platelet aggregation by causing irreversible inhibition of cyclooxygenase which synthesizes TXA2 to promote platelet activation
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What is the adverse reaction to aspirin?
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Increased risk for GI bleeding or bleeding in general, hemorrhagic stroke
(Enteric-coated tablets may not reduce the risk for GI bleeding) |
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What is the MOA of clopidogrel (Plavix)?
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-Adenosine Diphosphate (ADP) receptor antagonist
-blocks P2Y12 ADP receptors on platelets and prevents ADP-stimulated platelet aggregation |
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What are the therapeutic uses of aspirin?
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-ischemic stroke
-TIA -chronic stable angina -unstable angina -coronary stenting -acute MI -previous MI -primary prevention of MI |
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What are the therapeutic uses of clopidogrel?
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-prevents blockage of coronary artery stents
-reduces thrombotic events in patients with acute coronary syndromes (MI, ischemic stroke, vascular death) |
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What are the adverse effects of clopidogrel?
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-GI bleeding (similar to those of aspirin)
-need to be caution when using in combination with other drugs that promote bleeding |
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What are the thrombolytic drugs?
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-streptokinase (Streptase)
-alteplase (tPA) -tenecteplase (TNKase) -reteplase (Retavase) -urokinase (discontinued by manufacturer) |
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What is the MOA of streptokinase and alteplase?
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It binds to plasminogen to form active complex, which then converts plasminogen to plasmin and degrades fibrin in clots.
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What are the therapeutic uses of streptokinase?
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-acute coronary thrombosis (acute MI)
-DVT -massive pulmonary emboli |
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What are the adverse effects of streptokinase?
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-bleeding (excessive fibrinolysis can be reversed with IV aminocaproic acid (Amicar)
-antibody production -hypotension -fever |
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What is the difference between streptokinase and alteplase?
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Alteplase is slightly better than streptokinase for treating MI, but is most costly. It's also given at an accelerated schedule.
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What are the therapeutic uses for alteplase?
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-MI
-ischemic stroke -massive PE |
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What can aminocaproic acid (Amicar) be used for?
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It's used to prevent bleeding from use of streptokinase; it reverses the excessive fibrinolysis.
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How is a seizure defined?
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It is any disorder that alters the neuronal environment and may cause seizure activity.
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What are the general etiologies of seizures?
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-Cerebral lesions
-Biochemical disorders -Cerebral trauma -Epilepsy |
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What is the classifications of a partial seizure?
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Part of the brain surface is affected
-Simple partial: no impairment of consciousness during seizure -Complex partial: there is impairment of consciousness during seizure -With secondary generalization: onset of partial can evolve and progress to general and impairment of consciousness |
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What are the classifications of a generalized seizure?
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The entire brain surface is affected
-Absence (petit mal) (in children for short time) -Atypical absence (accompanied with myoclonic jerks nad automatisms (lip smacking or repetitive semi-purposeful movements) with the staring spell -Myoclonic -Atonic (drop attack) -Clonic -Tonic -Generalized tonic-clonic (grand mal) |
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Differentiate between tonic and clonic phase of seizures.
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Tonic phase: muscle rigidity, back arched
Clonic phase: violent rhythmic muscle contraction |
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When seizure medication has initiated, what four areas need to be monitored?
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-Drug evaluation (effectiveness, control of seizures, adjustment of dosage needed)
-Plasma drug levels (therapeutic levels, toxicity levels) -Promoting compliance (involve family and pt in taking responsibility) -Withdrawing AED (antiepileptic drugs): must be done slowly from 6 wks to several months, failure to gradually reduce is a frequent cause of SE |
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What is the MOA of phenytoin (Dilantin, Phenytek)?
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-broad spectrum anti-seizure drug
-active against all seizures except absent seizure (petit mal for children) -can suppress seizures without suppressing respirations -selectively inhibits sodium channels re-entry back into the neuron, depresses action potential -prevents spread of seizure from a hyperactive focus |
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What is the half life of phenytoin (Dilantin, Phenytek)?
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8-60 hours
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Describe the metabolism of phenytoin (Dilantin, Phenytek)?
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-the liver has a limited capacity to metabolize, which makes the dosage/plasma levels very difficult to manage
-possesses a very narrow index -can become toxic with small increase -can become sub-therapeutic with a small decrease -therapeutic dose is only slightly smaller than what is needed to saturate the hepatic enzymes -THUS a small change in dose gives a huge change in plasma levels |
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What are the adverse effects of phenytoin (Dilantin, Phenytek)?
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-CNS: nystagmus, sedation, ataxia, diplopia, cognitive impairment
-gingival hyperplasia -skin rash: morbilliform (resembling eruption of measles) & rare occurrence of Stevens-Johnson -pregnancy: teratogen, motor or mental deficiency, microcephaly -decrease synthesis of vitamin K and D |
