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Anti-platelets & fibrinolytics Flashcards

1
Q

Platelet aggregation is physiologically facilitated by

A
  • thromboxane (TXA2)
  • ADP receptor stimulation
  • GP IIb/IIIa receptor stimultation
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2
Q

platelet aggregation is pharmacologically inhibited by

A
  • TXA2 synthesis inhibitor aspirin
  • ADP receptor antagonists Ticlopidine and Clopidogrel
  • dipyridamole
  • GP IIb/IIIa receptor antagonists Abciximab
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3
Q

Use of aspirin & MOA

A

low dose aspirin (81-325)
Use: antiplatelet

MOA: irreversibly inhibit platelet COX enzyme by acetylating the enzyme and also inhibits thromboxane synthetase

  • as platelets cannot synthesize new COX (no nucleus)
  • no thromboxane TXA2 synthesis
  • antithrombotic effect lasts for 3 days

High dose aspirin = COX 1 and 2

Use: low dose daily prevents ischemic attack and MI

> 1000mg/day has NO anti platelet effect

  • high dose is anti-inflammatory dose
  • high dose inhibits prostacyclin (PGI) synthesis
  • PGI normally prevents platelet aggregation
  • therefore prophylactic benefit of aspirin as an anti platelet drug is always in low doses

MC use of aspirin = coronary artery disease

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4
Q

COX 1

A

COX1 = housekeeping; important with PG in mucous production

aspirin-induced ulcers result from inhibition of this –> not seen much with low-dose aspirin

Remember: aspirin acetylates serine residue on COX –> inhibits TXA2 synthetase

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5
Q

Ticlopidine: MOA, use, A/E

A

ADP receptor antagonist

MOA: blocks platelet ADP receptor and prevents platelet aggregation

Uses:

  • for prevention of TIA, post MI, unstable angina and as an alternative to aspirin
  • adjunct therapy with aspirin following coronary stent implantation to decrease incidence of stent thrombosis

A/E:
- severe neutropenia, thrombocytopenic purpura

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6
Q

GP IIb/IIIa receptor antagonists

A
  • Abciximab
  • Eptifibatide
  • Tirofiban
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7
Q

Fibrinolytics / Thrombolytics

A
  • streptokinase
  • urokinase
  • tissue plasminogen activator (tPA)

fibrinolytic therapy should be used ASAP to reestablish blood flow following AMI; >60% decrease in mortality post-MI if used within 3 hours!

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8
Q

Antifibrinolytics

A

aminocaproic acid

tranexamic acid

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9
Q

Clopidogrel: MOA, use, A/E

A

ADP receptor antagonist

MOA: blocks platelet ADP receptor and prevents platelet aggregation

Uses:

  • for prevention of TIA, post MI, unstable angina and as an alternative to aspirin
  • adjunct therapy with aspirin following coronary stent implantation to decrease incidence of stent thrombosis

A/E:
- less incidence of neutropenia or thrombocytopenia

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10
Q

Eptifibatide: MOA and use

A

GP IIb/IIIa receptor antagonist

MOA: Inhibit binding of fibrinogen to the GPIIb/IIIa receptor –> thereby inhibiting the final, common pathway of platelet aggregation

Use: given along with aspirin and heparin during coronary angioplasty (PTCA)
- markedly reduce the incidence of restenosis

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11
Q

Streptokinase

A

thrombolytic/fibrinolytic

  • obtained from streptococci

MOA: binds to circulating plasminogen–> converts to plasmin

A/E: bleeding, allergic reactions, hypotension, fever

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12
Q

alteplase

A

tPA

MOA: binds to & activates fibrin bound plasminogen (more local action on the thrombus)

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13
Q

Dipyridamole MOA

A

Inhibits phosphodiesterase –> increased cAMP –> prevents aggregation

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14
Q

Abciximab:

A

GP IIb/IIIa receptor antagonist

MOA: monoclonal antibodies directed against GP IIb/IIIa receptor complex

Use: given along with aspirin and heparin during coronary angioplasty (PTCA)
- markedly reduce the incidence of restenosis

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15
Q

urokinase

A

fibrinolytic/thrombolytic

- derived from human tissue

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16
Q

reteplase

A

tPA

MOA: binds to & activates fibrin bound plasminogen (more local action on the thrombus)

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17
Q

aminocaproic acid: MOA, Uses

A

antifibrinolytic

MOA: Inhibits the plasminogen activation

Uses: to treat excessive bleeding due to overdose of fibrinolytic agents

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18
Q

Tissue plasminogen activator (tPA)

A

fibrinolytic/thrombolytic
- Alteplase, reteplase (recombinant DNA technology)

MOA: binds to & activates fibrin bound plasminogen (more local action on the thrombus)

used to help re-canalize bv after AMI

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19
Q

Tirofiban: MOA and use

A

GP IIb/IIIa receptor antagonist

MOA: monoclonal antibodies directed against GP IIb/IIIa receptor complex

Use: given along with aspirin and heparin during coronary angioplasty (PTCA)
- markedly reduce the incidence of restenosis

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20
Q

tranexamic acid: MOA, Uses

A

antifibrinolytic

MOA: Inhibits the plasminogen activation

Uses: to treat excessive bleeding due to overdose of fibrinolytic agents

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21
Q

Anticoagulants

A
  • Heparin
  • warfarin (Oral anticoagulant)
  • dicumarol (Oral anticoagulant)
  • hirudin (direct thrombin inhibitor)
  • bivalirudin (direct thrombin inhibitor)
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22
Q

heparin: MOA, Pharmacokinetics,

A

Anticoagulant: indirect thrombin inhibitor

  • unfractionated Heparin (UFH)
  • low molecular weight heparins (LMWH)–longer DOA
  • monitor via aPTT

MOA: activates ATIII –> inactivates clotting factors in intrinsic pathway
- thrombin IIa, IXa, Xa

Pharmacokinetics:

  • hepatin is a strong acid and can be neutralized by basic compounds like protamine***
  • highly ionized –> not absorbed orally
  • -> does not cross placenta; safe in pregnancy*
  • given via IV/ S.C.
  • dose monitored by aPTT (activated partial thromboplastin time) –> normally 25-39 sec
  • with heparin: 45-75 sec; beyond this–>bleeding!
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23
Q

warfarin

A

Oral Anticoagulant

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24
Q

intrinsic coagulation system

A

Intrinsic pathway: factors XII, XI, IX, and VIII

  • begins with activation of factor XII (Hageman factor)
  • exposed sub-endothelial collagen and HMWK activate factor XII to form factor XIIa
  • factor XIIa is also known as activated Hageman factor
  • factor XIIa activates factor XI to form factor XIa
  • factor XIIa activates 3 substances:
  • –> factor XI to form factor XIa
  • –> plasminogen to form plasmin
  • –> kininogen system to produce chalkier and bradykinin
  • XIa activates factor IX to form IXa
  • IXa complexes with factor VIII, CA2+, and PF3 to form a four component complex: factor IXa, factor VIII, PF3 and Ca2+
  • in the final common pathway this complex activates factor X
    _____________________________________________
    XII –> XIIa
    XI –> XIa
    IX –> IXa
    VIII + IXa + PF3 + Ca2+ —>common pathway
Common pathway: 
X --> Xa
V + Xa + PF3 + Ca2+
prothrombin --> thrombin
fibrinogen --> fibrin monomer
fibrin monomer aggregate--> soluble fibrin --> cross-linked insoluble fibrin
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25
extrinsic coagulation pathway
``` Extrinsic pathway: factor VII - begins with activation of factor VII - Tissue Thromboplastin released from injured tissue activates factor VII resulting in formation of factor VIIa - in the final common pathway factor VIIa activates factor X _______________________________________ VII --> VIIa ----> common pathway: X --> Xa V + Xa + PF3 + Ca2+ prothrombin --> thrombin fibrinogen --> fibrin monomer fibrin monomer aggregate--> soluble fibrin --> cross-linked insoluble fibrin ```
26
dicumarol
Oral anticoagulant
27
Common Pathway
Factors X, V, II (prothrombin) and I (fibrinogen) - begins with activation of factor X by: --> factor VIIa (extrinsic pathway) --> four component complex [(factor IXa, factor VIII, PF3, Ca2+) intrinsic pathway] -activated factor Xa complexes with factor V, PF3, and Ca2+ to form a complex = the Prothrombin complex ----> prothrombin complex cleaves prothrombin to the enzyme thrombin _____________________________________ X --> Xa V + Xa + PF3 + Ca2+ prothrombin --> thrombin fibrinogen --> fibrin monomer fibrin monomer aggregate--> soluble fibrin --> cross-linked insoluble fibrin
28
LMW heparins: names, MOA, Advantages, A/E
enozaparin dalteparin tinzaparin - selectively inhibit Xa, less effect on thrombin - given subcutaneously advantages: - less hemorrhagic complication, less thrombocytopenia - equally efficacious - increased bioavailability - less frequent dosing, bc longer half life - less effect on aPTT A/E: BLEEDING! - close monitoring of activated partial thromboplastin time (aPTT) - PROTAMINE is used to stop bleeding due to heparin - Moderate & transient thrombocytopenia --> immune mediated - Osteoporosis on prolonged use
29
Hemopoietic agents used in treatment of anemias and hemopoietic growth factors
- iron - vitamin B12 - folic acid - erythropoietin - myeloid growth factors - platelet growth factor
30
hirudin
direct thrombin inhibitor
31
bivalirudin
direct thrombin inhibitor
32
Used to stop bleeding due to heparin
PROTAMINE
33
Enoxaparin: MOA, Advantages, A/E
LMWH - selectively inhibit Xa, less effect on thrombin - given subcutaneously advantages: - less hemorrhagic complication, less thrombocytopenia - equally efficacious - increased bioavailability - less frequent dosing, bc longer half life - less effect on aPTT A/E: BLEEDING! - close monitoring of activated partial thromboplastin time (aPTT) - PROTAMINE is used to stop bleeding due to heparin - Moderate & transient thrombocytopenia --> immune mediated - Osteoporosis on prolonged use
34
Direct Thrombin Inhibitors: names & MOA
Lepuridin bivalirudin argatroban - directly bind to thrombin and inhibits the downstream effects - obtained from proteins made by medicinal leech
35
Warfarin MOA
- decrease hepatic synthesis of Vit K dependent clotting factors: Prothrombin, VII, IX, X - by preventing the gamma carboxylation of glutamine residues of clotting factors - this is done by inhibiting Vitamin K Epoxide Reductase--> which prevents the regeneration of hydroquinone form of Vit K
36
Dalteparin: MOA, Advantages, A/E
LMWH - selectively inhibit Xa, less effect on thrombin - given subcutaneously advantages: - less hemorrhagic complication, less thrombocytopenia - equally efficacious - increased bioavailability - less frequent dosing, bc longer half life - less effect on aPTT A/E: BLEEDING! - close monitoring of activated partial thromboplastin time (aPTT) - PROTAMINE is used to stop bleeding due to heparin - Moderate & transient thrombocytopenia --> immune mediated - Osteoporosis on prolonged use
37
Lepuridin
Direct Thrombin Inhibitor - directly bind to thrombin and inhibits the downstream effects - obtained from proteins made by medicinal leech Uses: alternative to heparin in heparin-induced thrombocytopenia
38
Warfarin A/E
1. Bleeding: ecchymosis, epistaxis, hematuria - monitor, prothrombin time - treatment: stop the drug, Vitamin K1, fresh frozen plasma 2. Skin Necrosis: rare complication seen during first week of therapy with warfarin - due to reduced protein c synthesis - manifests as dermal necrosis of extremities or breast
39
Tinzaparin: MOA, Advantages, A/E
LMWH - selectively inhibit Xa, less effect on thrombin - given subcutaneously advantages: - less hemorrhagic complication, less thrombocytopenia - equally efficacious - increased bioavailability - less frequent dosing, bc longer half life - less effect on aPTT A/E: BLEEDING! - close monitoring of activated partial thromboplastin time (aPTT) - PROTAMINE is used to stop bleeding due to heparin - Moderate & transient thrombocytopenia --> immune mediated - Osteoporosis on prolonged use
40
Uses of Heparin
used when anticoagulation is required immediately (rapid anticoagulation) - DVT - PE - AMI - coronary angioplasty along with fibrinolytic - anticoagulant of choice during pregnancy* - Atrial fibrillation - cerebrovascular disease - vascular surgery - prosthetic heart valves
41
alternatives to heparin in heparin-induced thrombocytopenia
- Lepuridin | - argatroban
42
Bivalirudin
Direct Thrombin Inhibitor - directly bind to thrombin and inhibits the downstream effects - obtained from proteins made by medicinal leech Uses: used in combination with aspirin during angioplasty
43
Phytonadione
Preparation of Vitamin K1 - given orally - Vitamin K is a Cofactor for synthesis of clotting factors Prothrombin, factor VII, IX and X
44
Factors increasing Iron absorption
- acid - ascorbic acid - aminoacids - meat
45
Argatroban
Direct Thrombin Inhibitor - directly bind to thrombin and inhibits the downstream effects - obtained from proteins made by medicinal leech Uses: alternative to heparin in heparin-induced thrombocytopenia
46
Warfarin Pharmacokinetics
Inhibits synthesis of clotting factors by liver but doesn't affect clotting factors that's already made! - given orally --> onset of action delayed - highly bound to plasma proteins (99%) - crosses placenta --> can cause hemorrhagic disorder, bone defects in fetus - monitored by INR (international normalized ratio) - recommended INR = 2-3 INR = test prothrombin time / control prothrombin time
47
Warfarin Uses
same as heparin - used for long-term anticoagulation; FOR MAINTENANCE! - DVT, PE - AMI - Coronary angioplasty along with fibrinolytics - NOT anticoagulant of choice during pregnancy!!!!! - Atrial fibrillation - Cardiovascular disease - vascular surgery - prosthetic heart valves
48
filgrastim
granulocyte colony stimulating factor (G-CSF)
49
Vitamin K
Cofactor for synthesis of clotting factors Prothrombin, factor VII, IX and X - preparation: phytonadione (Vit K1) - given orally Uses: - obstructive juandice, liver disease - malabsorption syndromes - newborns (premature Vit K1 mg IM) - overdose of oral anticoagulants
50
Which form of iron is absorbed?
Fe2+ (ferrous) - max absorption in duodenum Fe3+ = ferric iron
51
Oral iron preparations: types & A/E
- ferrous sulfate - ferrous gluconate - ferrous fumerate A/E: - Epigastric pain - constipation - metallic taste - nausea, vomiting - staining of teeth
52
Factors decreasing Iron absorption
- antacids - phosphates - phytates - tetracyclines - presence of food
53
- Vomiting, hematemesis, bloody diarrhea followed by shock, | - severe metabolic acidosis, coma and death
acute iron poisoning - common in infants and children Treatment: Deferrioxamine: iron chelating agent
54
parenteral iron: names, indications for use, and uses
- iron dextran (IV/IM) - sodium ferric gluconate complex (only IV) - iron sucrose (only IV) indications for use: - oral iron not tolerated - severe deficiency - malabsorption - non-compliance Uses: 1. iron deficiency anemia - nutritional deficiency (premature infants, growing children) - anemia of pregnancy - blood loss (GI bleeding) - malabsorption 2. pregnant and lactating women -- prophylaxis
55
Cyanocobalamine
Vitamin B12 Preparation Absorption: intrinsic factor (gastric parietal cell) + Vit B12 --> absorbed in distal ileum Uses: megaloblastic anemia and pernicious anemia
56
sargramostim
granulocyte/macrophage colony stimulating factor (CM-CSF)
57
Folic Acid
Folic acid --Folic reductase (enzyme)--> dihydrofolic acid --dihydrofolate reductase (enzyme)--> tetrahydrofolic acid dihydrofolate reductase (enzyme) is inhibited by methotrexate Uses: megaloblastic anemia caused by a) nutritional deficiency, alcoholics, liver diseases b) pregnancy, malabsorption d) pregnancy--maternal FA deficiency, associated with neural tube defects (i.e. spinabifida) c) drugs: - phenytoin: antiepileptic - sulfonamides: treat malaria, antibacterial (in high [ ] --> anemia) - methotrexate: anti-cancer drug - INH: tx malaria - OCP Methotrexate toxicity: - leucovorin (aka folinic acid = active form of folic acid)/citrovorum factor/folinic acid - Mtx-DHFR inhibitor (FA is not effective) Leucovorin rescue: giving leucovorin when used to give high dose of methotrexate because rescuing bone marrow cells
58
Hydroxyocobalamine
Vitamin B12 Preparation Absorption: intrinsic factor (gastric parietal cell) + Vit B12 --> absorbed in distal ileum Uses: megaloblastic anemia and pernicious anemia
59
Acute Iron Poisoning
- common in infants and children Symptoms: - Vomiting, hematemesis - bloody diarrhea followed by shock - severe metabolic acidosis, coma and death Treatment: Deferrioxamine: iron chelating agent
60
Hemopoietic growth factors
recombinant human erythropoietin: - erythropoitin - darbopoietin - colony stimulating factors: G-CSF and GM-CSF Uses: - anaemic of chronic renal failure (because doesn't form enough EPO --> anemia) - cancer chemo induced anemia - anemia in AIDS patients--Zidovudine--> causes BM suppression
61
Myeloid Growth Factors
promote WBC - granulocyte colony stimulating factor (G-CSF) -->filgrastim - granulocyte/macrophage colony stimulating factor (CM-CSF)-->sargramostim Use: to treat neutropenia with anticancer drugs & zidovudine
62
Megakaryocytic Growth Factors
``` Interleukin 11 (oprelvekin) - stimulate the formation of megakaryocytic and increase their number in peripheral blood ``` Use: thrombocytopenia after a cycle of cancer chemotherapy
63
Deferrioxamine
iron chelating agent | - used to treat acute iron poisoning
64
Which anticoagulant has a delayed onset?
Warfarin Heparin has an immediate onset

Pharm (32 decks)

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