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RCS > L20- Drugs Used in Disorders of Coagulation > Flashcards

L20- Drugs Used in Disorders of Coagulation Flashcards

1
Q

list the 3 steps hemostasis

A

1) primary hemostasis- platelet aggregation
2) secondary hemostasis- coagulation
3) fibrinolysis: via plasmin

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2
Q

plasmin breaks down….

A
  • fibrinogen
  • fibrin

=> degradation products

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3
Q

what are the types / functions of drugs used in disorders of coagulation

A

1) drugs used to reduce clotting

2) drugs used to reduce bleeding

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4
Q

what are the types of drugs used to reduce clotting

A
  • platelet aggregation inhibitors
  • anticoagulants
  • thrombolytics
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5
Q

platelet aggregation inhibitors act on…..

A
  • dec platelet synthesis

- inhibit actions of chemical signals

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6
Q

what are the 4 platelet aggregation inhibitors

A
  • cyclooxygenase inhibitors
  • ADP receptor blockers
  • phosphodiesterase inhibitors
  • blocker of platelet GP IIb/IIIa receptors
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7
Q

ASA functions as a (1) inhibitor via (2) interaction. The end goal and result is to decrease (3) levels which are responsible for (4).

A

1- COX (1 and 2)
2- irreversible acetylation
3- TX-A2
4- platelet degranulation and aggregation // vasoconstriction

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8
Q

describe the platelet aggregation interaction

A

1 fibrinogen binding to 2 GP IIb/IIIa on 2 different platelets

note- this reaction / interaction occurs as a result of Ca influx

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9
Q

ASA is used for…..

A
  • prophylactic Tx of TIA/CVA (transient cerebral ischemia)

- reduce incidence of recurrent MI / dec mortality in post-MI patients

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10
Q

(1) and (2) are the ADP receptor blockers that work via a (3) interaction with (4).
- indicate whether (1)/(2) is preferred and why

A

1- clopidogrel (preferred b/c fewer adverse effects)
2- ticlopidine
3- irreversible
4- P2Y12 (one of two ADP receptors)

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11
Q

Clopidogrel is a prodrug that is converted to active metabolite via (1). List the contraindications for using clopidogrel, (2).

A

1- CYP2C19

2: (do not use….)
- in poor CYP2C19 metabolizers
- with Omeprazole, a CYP2C19 inhibitor

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12
Q

clopidogrel is used for….

A

reduce rate of stroke, MI, death in patients with recent MI, stroke OR with acute coronary syndrome

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13
Q

list the 2 phosphodiesterase inhibitors and their associated uses

A
  • Dipyridamole: stroke prevention

- Cilostazol: intermittent claudication

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14
Q

list the blockers of platelet GP IIb/IIIa receptors (indicate preferred drug) and what they treat

A

Abciximab, Eptifibatide, Tirofiban** (preferred)

-adjuncts in PCI (stent/angioplasty) for prevention of cardiac ischemic complications

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15
Q

list anticoagulants

A
  • indirect thrombin (IIa) and factor Xa inhibitors
  • vitamin K antagonist
  • direct thrombin (IIa) inhibitors
  • direct factor Xa inhibitors
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16
Q

list the indirect thrombin (IIa) and factor Xa inhibitors

A
  • unfractionated heparin (UFH)
  • low molecular weight heparins (LMWH)
  • fondaparinux
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17
Q

UFH and LMWH are administered via (1), it has a (fast/slow) action and used for (3)

A

1- injectable
2- rapid
3- interfere with formation of thrombi

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18
Q

UFH and LMWH:

1) describe structure (+ weight
(2) explain source

A

1- mixture of straight-chain sulfated mucopolysaccharides (highly sulfonated => very negative)
-UFH: 5000-30000 MW
-LMWH (enoxaparin): 1000-5000 MW
2- isolated from bovine lung or porcine intestinal mucosa

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19
Q

compare pharmacokinetic factors of UFH and LMWH

A

-equal efficacy

LMWH: higher bioavailability, longer half-life, requires less frequent dosing requirements

LMWH are becoming more preferred

20
Q

heparin binds and accelerates the action of (1) which will inhibit (2)

A

1- antithrombin III

2- thrombin (IIa), IXa, Xa

21
Q

(T/F) UFH and LMWH inactivate factor IIa and Xa equally

A

F:

  • UFA inhibits both IIa, Xa (due to ternary complex formation with antithrombin III)
  • LMWF inhibits Xa&raquo_space;> IIa (does not form ternary complex with antithrombin III)
22
Q

_____ is used to monitor the performance of Heparin

A

aPTT: activated partial thromboplastin time (integrity of the intrinsic / common pathways)

-LMWH usually doesn’t need monitoring, assessed with anti-factor Xa assays

23
Q

list the uses of heparin

A

-DVT
-pulmonary embolism
-MI
(drug of choice during pregnancy)

24
Q

list the adverse effects of heparin

A
  • bleeding
  • hypersensitivity reactions
  • HIT (heparin induced thrombocytopenia: type II worse than benign type I)
25
Q

how does heparin cause type II HIT

A

(heparin induced thrombocytopenia)

  • antibodies recognize heparin and platelet protein (Platelet Factor 4) complex
  • Ig binds complex and activates Fc receptor on platelet

=> platelet aggregation and release of platelet contents (positive feedback)
-thrombocytopenia and thrombosis

26
Q

heparin overdose or bleeding is treated with…..

A

protamine sulfate (positively charged, mops up heparin)

27
Q

Fondaparinux:

(1) structure
(2) binds to???
(3) inhibitor of???

A

1- synthetic pentasaccharide (sequence 5 carbohydrates)
2- antithrombin III
3- factor Xa specifically

28
Q

(1) is the vitamin K antagonist by inhibiting (2) so that factors (3) will not have (4)

A

1- warfarin
2- vitamin K epoxide reductase
3- II, VII, IX, X
4- γ-carboxyglutamyl side chains

29
Q

warfarin effects factor _____ the most

A

factor VII, extrinsic pathway (+ protein C, intrinsic pathway)

30
Q

warfarin is used to treat and prevent (1) and (2) following (3) or used to treat (4) used alone

A

1- DVT
2- pulmonary embolism
3- heparin
4- thromboembolic AFib

31
Q

list the adverse effects of warfarin

A
  • hemorrhage
  • cutaneous necrosis (due to reduced protein C activity)
  • category X in pregnancy (hemorrhagic disorder in fetus, and serious birth defects)
32
Q

list the parenteral DTIs, include how it is monitored and what it is used for

A

(direct thrombin inhibitors)

  • desirudin
  • bivalirudin
  • argatroban
  • monitor via aPTT
  • used in patients undergoing PCI
33
Q

list the oral DTIs, include how it is monitored and what it is used for

A

(direct thrombin inhibitors)
-dabigatran etexilate (prodrug converted to dabigatran)

  • no monitoring necessary
  • prevents and treats DVT, pulmonary embolism
34
Q

list the direct factor Xa inhibitors, include route of administration, how it is monitored, and what it is used for

A

-apixaban, rivaroxaban

  • oral
  • no monitoring necessary
  • prevents and treats DVT, pulmonary embolism
35
Q

why are direct thrombin and factor Xa inhibitors better than Warfarin

A

(dabigatran, apixaban, rivaroxaban)

  • equivalent antithrombotic efficacy
  • lower bleeding rate
  • quicker onset of action
  • predictable pharmacokinetics
  • wider therapeutic window
  • no monitoring required
  • fewer drug interactions
36
Q

why are thrombolytics (fibrinolytics) useful in comparison to anticoagulants

A
  • lyses existing blood clots –> restores vessel patency before distal tissue necrosis
  • anticoagulants only prevent thrombi formation

(acts by converting plasminogen to plasmin)

37
Q

list all the thrombolytics (how do they act)

A
  • streptokinase, urokinase (non-fibrin selective)
  • alteplase, reteplase, tenecteplase (fibrin selective)
  • *they convert plasminogen to plasmin
38
Q

streptokinase is a (1) type drug found in (2) and is used for (3)

A

1- thrombolytic
2- β-hemolytic streptococci
3- rarely used

39
Q

urokinase is a (1) type drug found in (2) and is used for (3)

A

1- thrombolytic
2- human kidney (+ urine)
3- lysis of pulmonary emboli

40
Q

describe the MOA of alteplase, reteplase, tenecteplase

A
  • t-Pa: tissue plasminogen activator, serine protease produced by human endothelial
  • t-Pa activates plasminogen bound to fibrin
  • t-Pa is ‘fibrin selective’
41
Q

list the uses for alteplase, reteplase, tenecteplase

A

Alteplase: recombinant t-Pa, used for acute MI, acute ischemic stroke

-Reteplase, Tenecteplase: recombinant variants of t-Pa, longer half-lives

42
Q

list the drugs used to treat bleeding

A
  • plasminogen activator inhibitors
  • protamine sulfate
  • vitamin K
  • plasma fractions
43
Q

The main plasminogen activation inhibitors are (1) and (2). They are used in (3) and (4).

A

1- aminocaproic acid
2- tranexamic acid
3- adjunct hemophilia therapy
4- therapy to counter bleeding via fibrinolytic therapy

44
Q

(1) is a chemical antagonist of heparin because its structure is highly composed of (2)

A

1- protamine sulfate

2- arginine, high positive charge

45
Q

vitamin K__ is administered in ______ fashion at birth

A

vitamin K1, injected IM at birth

46
Q

Vitamin K is used to treat (1) via (2) administration. It takes (3) for the onset of effect which lasts (4). If immediate hemostasis is required then (5) can be used.

A 
1- drug induced hypoprothrombinemia
2- oral, parenteral
3- 6 hrs
4- 24 hrs
5- fresh frozen plasma can be infused
47
Q

plasma fractions are used to (1), most commonly (2) and (3)

A

1- replace deficient coagulation factors
2- factor VIII
3- factor IX
(2/3- mostly inherited conditions)

RCS (29 decks)

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