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PAS- II PHARMACOTHERAPEUTICS > ANTICOAGULANTS, ANTIPLATELET DRUGS AND FIBRINOLYTIC AGENTS > Flashcards

ANTICOAGULANTS, ANTIPLATELET DRUGS AND FIBRINOLYTIC AGENTS Flashcards

1
Q

_____ – Arrest of blood loss from damaged vessels

  • Platelet _____ and activation
  • Blood _____ (_____ formation)
A

Hemostasis
adhesion
coagulation
fibrin

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2
Q

thrombosis

  • Inappropriate activation of haemostatic mechanisms
  • -_____ thrombosis –associated with stasis of blood
  • -_____ thrombosis –associated with atherosclerosis
A

Venous

arterial

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3
Q

_____: A portion of thrombus may break away , travel as an embolus and lodge downstream, causing ischemia and infarction

A

embolus

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4
Q

laboratory tests

  • _____ – To assess the function of platelets
  • -Normal 2-7 mins
  • Platelet count (Platelet function test) – To quantify platelet function
  • -Normal range: 150,000-450,000/µl
  • Partial thromboplastin time (APTT) – To measure the speed of _____ pathway
  • -Normal range: 25+- 10 seconds
  • Prothrombin time – To measure the speed of _____ pathway
  • -International normalized ratio (normal range 1.0)
A

Bleeding time
‘Intrinsic’
‘Extrinsic’

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5
Q

laboratory tests

  • Clotting time –
  • -Normal _____ mins
  • Factor VIII coagulant level in plasma (_____) < 50%
  • Factor IX levels (_____)
  • _____ ds – v WF antigen and Ristocetin cofactor (RcoF)
  • -Normal value is 100% (Range is 50 -150%)
  • -Levels of factor VIII parallels v WF
A

8-15
Hemophilia A
Hemophilia B
Von Willibrand’s

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6
Q

drug therapy

  • To promote _____
  • To prevent or treat _____ or thromboembolism
A

hemostasis

thrombus

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7
Q

defective hemostasis
-Deficiencies of clotting factors –
Hereditary –
-Classical hemophilia (lack of factor _____)
-Hemophilia B or Christmas disease caused by lack of factor _____ also called Christmas factor
-Missing factors can be supplied by giving _____ or concentrated preparations of factor VIII or factor IX

Acquired clotting defects –

  • Liver disease,
  • _____ deficiency,
  • Excessive oral anticoagulant therapy –
  • Require treatment with vitamin K
  • Following excessive _____ therapy
  • Difficulty in staunching hemorrhage following surgery or for menorrhagia
A 
VIII
IX
fresh frozen plasma
Vitamin K
coagulation
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8
Q

vitamin k

  • _____ vitamin occurring naturally in plants
  • Requires bile salts for absorption
  • Essential for formation of factor_____, _____, _____, _____ as well as protein _____ and protein _____
  • Acts as a cofactor for gamma-glutamyl carboxylase
  • Enzyme is required for carboxylation of factors in the liver and also of protein C and S (natural anticoagulants)
  • Activated by _____ in the _____
  • Given orally or iv
  • Synthetic preparation (Menadiol sodium phosphate)
A 
Fat soluble
 II, VII, IX, X
C
S
epoxide reductase
liver
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9
Q

clinical uses

  • treatment and prevention of _____ resulting from the use of oral _____ like warfarin
  • in babies to prevent hemorrhagic disease of new born
  • in adults, for spruce, coeliac ds, steatorrhoea and obstructive jaundice
A

bleeding

anticoagulants

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10
Q

THROMBOSIS AND VIRCHOW’S TRIAD

-Formation of _____ within the vasculature in the absence of _____

A

hemostatic plug

bleeding

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11
Q 
thrombosis 
Consequences – 
-Myocardial infarction, 
-Stroke, 
-DVT, 
-Pulmonary embolus

Drugs used to prevent or treat red thrombus are –

  • _____ (Heparin and newer antithrombins)
  • _____ (Warfarin and related compounds)

Drugs used for platelet-rich white thrombi are –

  • Antiplatelet drugs (aspirin) and
  • Fibrinolytic drugs
A

Injectable anticoagulants

Oral anticoagulants

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12
Q

INJECTABLE ANTICOAGULANTS HEPARIN AND LMWHs

  • Heparin - is present with histamine in mast cells
  • Heparin fragments (LMWHs) are used increasingly in place of heparin
  • MOA – Activate _____
  • Antithrombin III inhibits _____, _____ and other serine proteases
  • Thrombin is more sensitive to the inhibitory effect of heparin-antithrombin III complex as compared to factor X
  • LMWHs increase the action of antithrombin III on _____ but not on _____
A 
antithrombin III
thrombin (II)
factor Xa
factor Xa
thrombin
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13
Q

ADMINISTRATION AND PHARMACOKINETICS
HEPARIN –
-Not absorbed from gut because of its charge and large size
-Given iv, sc (im injection can cause hematoma)
-Onset of action is _____ after iv injection but onset is delayed by 1 hour after _____
-Elimination T/2 is 40-90 minutes
-In emergencies- bolus dose is followed by continuous infusion
-The dosage is monitored with _____ and dosage is adjusted to achieve a value within (1.5 -2.5 times control)

A

immediate
sc inj
APTT

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14
Q

unwanted effects

  • Hemorrhage – Stop the therapy, if necessary give _____ iv. It is basic and forms an inactive complex with heparin
  • _____ – Two types (Transitory early and Serious thrombocytopenia 2-14 days later)
  • Thrombosis and DIC – Abs also bind to glycosaminoglycans on the surface of endothelial cells, leading to immune injury of the vessel wall
  • _____ – With long term heparin (>6 months), seen usually during pregnancy
  • Hypoaldosteronism – Consequent hyperkalemia
  • Hypersensitivity reactions – Rare with heparin but more common with protamine sulfate
A

Protamine sulfate
Thrombocytopenia (HIT)
Osteoporosis

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15
Q

HEPARIN INDUCED THROMBOCYTOPENIA(HIT)

  • Suspect if recently treated with heparin
  • Platelet counts decline within 5- 10 days in pt with no previous exposure to heparin
  • Platelet activating abs recognizing multimolecular complexes bound to unfractionated heparin or LMWH
  • Characteristics – Erythematous or necrotizing skin reactions at the site of injection or deep vein thrombosis, pulm emboli, stroke, MI
  • Test – ELISA
  • If confirmed, _____ is stopped immediately and treatment is started with _____
A

heparin

nonheparin anticoagulant

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16
Q

LMWHs

  • Given sc
  • Longer elimination T/2 and is independent of _____
  • Do not prolong _____
  • Eliminated by _____ excretion
  • As safe and effective as unfractionated heparin and more convenient to use
A

first order kinetics
APTT
renal

17
Q

ORAL ANTICOAGULANTS WARFARIN

  • Mechanism – Inhibit the reduction of _____ to its active form (hydroquinone), therefore _____ of _____ acid residues in clotting factors _____, _____, _____, _____ does not occur
  • Onset of action depends on the _____ of the factors
  • -VII- T/2 is 6 hrs and is affected first and then IX, X, XI (24, 40, 60 hours)
A 
vitamin K
gamma carboxylation
glutamic
II, VII, IX, X
elimination half life
18
Q

ADMINISTRATION AND PHARMACOKINETICS

  • Warfarin is given orally
  • Absorbed quickly and totally from GIT
  • Has small _____ and binds strongly to plasma albumin
  • Peak concentration is reached in one hour but the pharmacological effects set in 48 hours later
  • The effect on PT starts at 12-16 hours and lasts for 4-5 days
  • Warfarin is metabolized by P450 system
  • Crosses _____ so is not given in pregnant pts (_____ in babies)
  • Warfarin – 10 L/70kg, Digoxin – 500 L/70kg, Lidocaine – 120 L/70kg
A

volume of distribution
placenta
intracranial hemorrhage

19
Q

THERAPEUTIC CHALLENGES WITH WARFARIN

  • Requires a careful balance between giving too little or too much
  • Effects are seen only after 2 days
  • Numerous drug interactions
  • _____ is a must – _____ (Dose is adjusted to give an INR of 2-4)
  • Duration of treatment varies- to prevent thromboembolism in _____ treatment is _____ term
A

Monitoring
INR
chronic atrial fibrillation
long

20
Q

FACTORS THAT POTENTIATE ORAL ANTICOAGULANTS

  • _____ disease
  • High _____ rate – Fever and thyrotoxicosis cause increased degradation of clotting factors
  • Drugs that inhibit hepatic drug metabolism potentiate _____ –
  • -Cimetidine, imipramine, co-trimoxazole, chloramphenicol, ciprofloxacin, metronidazole, amiodarone and azole antifungals
A

Liver
metabolic
warfarin

21
Q

FACTORS THAT POTENTIATE ORAL ANTICOAGULANTS

  • Drugs that inhibit _____ function will increase the risk of bleeding –
  • -NSAIDS, Aspirin, and antibiotics like moxalactam, carbenicillin
  • Drugs that displace _____ from binding sites on _____ –
  • -NSAIDs and Chloral hydrate
  • Drugs that inhibit reduction of vitamin _____ – _____
  • Drugs that decrease the availability of vitamin K – Broad spectrum antibiotics
A 
platelet
warfarin
plasma albumin 
K
cephalosporins
22
Q

FACTORS THAT LESSEN THE EFFECT OF ORAL ANTICOAGULANTS

  • Physiological state/disease
  • Conditions (_____) with increased coagulation factor synthesis
  • _____ – Reduced degradation of coagulation factors
  • Drugs –
  • -Vitamin _____
  • -Induce hepatic P450 enzymes – _____, _____, _____, _____)
  • -Reduce absorption – _____
A 
pregnancy
Hypothyroidism
K
Rifampicin, Carbamazepine, Barbiturates, Griseofulvin
cholestyramine
23
Q

UNWANTED EFFECTS

  • Hemorrhage into bowel or brain
  • Is teratogenic
  • Necrosis of soft tissue (breast tissue, buttock) due to thrombosis in venules due to inhibition of biosynthesis of protein C
  • Tt of overdose/increased INR –
  • -Withhold _____
  • -Administer _____, _____ or coagulation factor concentrates (for life threatening bleeding)
A

Warfarin,
Vit k
fresh plasma

24
Q

DIRECT THROMBIN INHIBITORS (DTIs)

  • Directly inhibit thrombin to delay clotting
  • Hirudin, the first parenteral DTI to be used, was isolated in the late 1800s from the medicinal leech,Hirudo medicinalis.
  • Bivalent DTIs include Bivalirudin and Lepirudin, and bind both the active site (N-terminus) and the fibrinogen-binding exosite (C-terminus) of thrombin
  • -_____ does not interact with HIT abs
A

Lepirudin

25
Q

DIRECT THROMBIN INHIBITORS (DTIs)

  • Univalent DTIs bind only the active site and include Argatroban and Dabigatran
  • -Argatroban is not given in pts with _____(hepatic metabolism)
  • -Dabigatran is contraindicated in _____ (renal excretion)
  • These smaller molecules do not need monitoring, have a _____therapeutic indexand can be administered orally.
  • Dabigatran is given _____, others are _____
  • Uses – HIT, PCI in acute coronary syndrome, stroke prevention
A 
hepatic dysfunction 
renal failure
wide
orally
parenteral
26
Q

LAB MONITORING OF DTIs

  • _____(TDM) – is required
  • -No reversal agents
  • -Elevated levels carry the risk of life-threatening _____
  • _____ (aPTT) –Measures the efficacy of both the intrinsic and the common coagulation pathways and is the method of choice in US.
A

Therapeutic drug monitoring
bleeding
Activated partial thromboplastin time

27
Q

FACTOR Xa INHIBITORS

  • Factor Xa is central to the propagation of coagulation.
  • Activated Factor X, bound as part of the _____ complex on the surface of activated platelets, converts large amounts of _____ to _____, stimulating the so-called _____.
A

prothrombinase
prothrombin
thrombin
‘thrombin burst’

28
Q

INDIRECT FACTOR Xa INHIBITORS

  • Fondaparinux – a synthetic indirect inhibitor of Factor Xa
  • Potentiates the rate of _____ of Factor Xa by _____ and, unlike heparin, does not inactivate _____
  • Does not inhibit Factor Xa bound in the prothrombinase complex; therefore, does not completely inhibit Factor Xa
  • Administered _____, limiting long-term use
A

neutralization
antithrombin
thrombin
subcutaneously

29
Q

DIRECT FACTOR Xa INHIBITORS

  • Rivaroxaban, Apixaban and Edoxaban directly engage the active site of the Factor Xa molecule
  • -Inhibit both _____ Factor Xa in plasma and Factor Xa attached to the _____
  • -Administered _____
  • Are ideal anticoagulants –
  • -Oral administration
  • -_____ regimens
  • -_____ onset and offset of action
  • -Predictable pharmacokinetics and pharmacodynamics
A 
free
prothrombinase complex
orally
Fixed-dose
Rapid

PAS- II PHARMACOTHERAPEUTICS (11 decks)

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