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Heme 2 > Pharm Treatment of Clotting Disorders > Flashcards

Pharm Treatment of Clotting Disorders Flashcards

1
Q

Anticoagulants inhibit the ____ or ____ of clotting factors.

A

action or formation

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2
Q

Examples of oral anticoagulants

A

Warfarin (coumadin, jantoven) *most widely used

Dabigatran (pradaxa) (IIa) (new)
Apixaban (eliquis) (Xa) (new)
Rivaroxaban (xarelto) (Xa) (new)

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3
Q

Warfarin
MOA
Time to achieve full therapeutic effect

A

Inhibits the synthesis of vitamin K dependent coagulation factors II, VII, IX, X and Protein C and Protein S.

*it doesn’t block them, it block the PRODUCTION of them

36-72 hours
-Normal clotting factors need to clear from the circulation

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4
Q

What is Warfarin used for?
Indications
Why must the patient be monitored closely
What is dosing based on

A

Used to prevent further clot formation

  • venous and arterial thromboembolism
  • pulmonary embolism
  • stroke embolism
  • stroke prevention in A. fib
  • thrombus prevention is cardiac valve replacement
  • stroke
  • TIA
  • prevention of clots

Must be monitored closely because of the narrow therapeutic range

Dosing based on PT/INR

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5
Q

What is normal INR?

What is the INR range for most warfarin indications?

A

1.0 normal

Warfarin INR- 2.0-3.0

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6
Q

How soon should the INR be checked after each dose change?

A

2-3 days

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7
Q

When should a pt take warfarin?

A

dosing depends on everything (pt, meds, etc.)

start with 5mg nightly

  • -eating could disrupt absorption
  • -can test in the am with little interactions

-warfarin is highly protein bound which leads to many drug interactions

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8
Q

What are the major drug interactions of warfarin that can lead to life threatening bleeding (LTB)?

A

Just assume that every drug interacts with warfarin.

  • Statins (cholesterol lowering)
  • most antibiotics
  • NSAIDs
  • drugs cleared through the liver
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9
Q

Food interactions with warfarin that lower the INR?

A
  • vitamin K containing foods (dark leafy greens, green tea)
  • smoking/tobacco

-Alcohol INCREASES

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10
Q

Warfarin

adverse events

A

LTB*
Skin necrosis* (leading to gangrene)
–purple toe syndrome (cholesterol emboli to the feet)
bleeding!

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11
Q

How to manage a pt with elevated INR:
5
LTB

A

5- hold warfarin and oral, IV or SQ Vitamin K

  • SQ absorption is variable
  • IV 1-2 hours later
  • Oral 24-48 hours later

LTB- vitamin K, factor VII, and FFP/ prothrombin concentrate

Vitamin K is the antidote.

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12
Q

Do anticoagulation clinics exist?

A

yep

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13
Q

How long should warfarin be held when anticipating a surgical or invasive procedure?

A

5 days

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14
Q

Why is “bridging” with heparin important for initiation of therapy and for patients that may need procedures?

A

Use heparin for 3-5 days when starting warfarin to prevent coagulation. Warfarin initially inhibits Protein C and S and ATIII (which help stop clotting) making you hypercoaguable.

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15
Q

Pros and Cons to new oral anticoags (compared to warfarin)

A

Pros

  • no need for routine labs
  • not affected by food
  • not as many drug interactions

Cons

  • no antidote
  • no way to monitor anticoagulation
  • dose adjustments likely needed for renal pts
  • not for use in valvular heart disease
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16
Q

Examples of parenteral anticoagulants

A 
Unfractionated Heparin (UFH)
-Heparin

Low molecular weight heparin (LMWH)

  • enoxaparin (lovenox)
  • dalteparin (fragmin)
  • fondaparinux (arixta)
17
Q

Heparin

MOA

A
  • Potentiation of the action of antithrombin III and inactivating thrombin, IX, X, XI, XII, and plasmin
  • prevents the conversion of fibrinogen to fibin
18
Q

Why is frequent monitoring needed in heparin pts?
What test monitors?
Resistance can be seen in?
Dosing?

A
  • due to a narrow therapeutic window
  • PTT
  • seen more commonly in acute illness with antithrombin III deficiency
  • bolus followed by IV drip
19
Q

Heparin
Indications
CI
Adverse effects

A
  • DVT
  • PE
  • A fib
  • MI
  • Arterial or venous thrombosis

CI- anaphylaxis and recent major surgery or ongoing bleeding

AE- bleeding, hypersensitivity rxns, transaminitis (bump in liver enzymes), heparin induced thrombocytopenia

20
Q

What is the antidote for heparin?

A

Protamine sulfate

  • in the event of severe bleeding or overdose
  • slow IV infusion to prevent anaphylactic rxn
  • can be used for both LMWH and UFH
21
Q

Heparin Induced Thrombocytopenia (HIT)
What type of heparin is it most likely to occur with?
What is is?

A

Most likely to occur with UFH but can occur with both UFH and LMWH

HIT is a serious complication of Heparin therapy

  • creates a pro-thrombotic state
  • antibodies bind: platelet factor 4 antibodies bind to heparin and platelets
  • platelets are activated and destroyed
  • occurs 4-5 days after the initiation of therapy
22
Q

HIT
Dx criteria
Labs

A

Noted when platelets drop by 50% after initiation of therapy

Labs

  • platelet factor 4 antibody
  • serotonin release assay (high=aggregation)
23
Q

HIT

tx

A

1st- STOP HEPARIN

  • give alternative anticoag like a direct thrombin inhibitor
  • no platelet transfusion
  • do not give warfarin until platelet count increases
24
Q

Advantages to LMWH

A
  • can be given SQ once or twice daily without need for labs for daily monitoring
  • lower risk of HIT
  • Safer than UFH for extended administration
25
Q

LMWH
MOA
Dosing depends on?
Time to effect?

A
  • inhibits Xa and accelerate ATIII
  • indirect thrombin inhibitor
  • LMWH more strongly inhibits Xa that UFH

Dosing varies depending on the indication, renal function, and drug

2 hours with peak effect at 4 hours

*if you need to know drug levels, you can check with a lab for anti-Xa activity

26
Q

Antiplatelet drugs inhibit ______ _____ and prevent _____ _____.

Examples?

A

inhibit platelet aggregation and prevent platelet plugs

Aspirin
P2Y12 antagonists (plavix, effient, brilinta)
Dipyridamole (aggrenox, used in combo with ASA)
GIIb/IIIa antagonists (reopro, integrelin)

27
Q 
Aspirin
reversible or irreversible?
MOA
Peak effects?
Used for the prevention of?
A

Irreversible platelet inhibitor

Prevents the formation of clots by inhibition of the platelet plug

rapid absorption with peak effects in 1 hour

Thromboembolism

28
Q

ASA
Dosing
SE

A

Primary prevention- 81mg daily
secondary prevention- depends, 81-325mg daily
acute coronary syndrome- 325 mg chewed

SE

  • bleeding
  • administer with food to decrease GI disturbance, H2 and PPIs may decrease gastritis and GI bleeding
  • tinnitus at higher doses
  • resistance
  • allergy
  • stop 4 days prior to surgery
29
Q

Clopidogrel (Plavix) and other P2Y12 antagonists
Used for the treatment and prevention of?
MOA
reversible or irreversible?
Adverse Effects

A

acute coronary syndrome and thromboembolic events

The binding of ADP to the (type 2 purinergic) receptor (P2Y12) is blocked and prevents the activation of GPIIb/IIIa complex therefore preventing platelet aggregation.

-Basically it blocks the receptor site. The receptor normally allows the platelet bridge to form and aggregate.

IRREVERSIBLE inhibition of platelet activation and aggregation is noted

AE

  • bleeding
  • multiple drug interactions with plavix
  • stop 7 days prior to surgery
30
Q

Dipyridamole
indications
MOA

A

Indications

  • secondary prevention in patients following stroke and TIA
  • used often with aspirin in a single pill called aggrenox

MOA
-causes an accumulation of adenosine, c-AMP (these mediators cause vasodialation and inhibit platelet aggregation

31
Q

GPIIb/IIIa antagonists: (Reopro, Integrelin)
Indications
SE

A
  • most powerful platelet inhibitor
  • decrease platelet bridge formation

Indication

  • acute coronary syndrome
  • clot prevention during percutaneous coronary intervention

SE

  • bleeding
  • thrombocytopenia
  • allergy
32
Q 
Thrombolytic drugs
AKA
Examples
MOA
Indications
SE
A

Fibrinolytics

tPA, streptokinase, Urokinase

Breakdown existing clots. Convert plasminogen to plasmin to facilitate breakdown of the fibrin strands

Indications

  • MI if >90 min to PCl
  • Stroke within the first few hours
  • massive PE with unstable hemodynamics
  • limb threatening ischemia

SE

  • massive LTB
  • use hospital checklist prior to administration

**these are very dangerous drugs. We don’t give these.

Heme 2 (8 decks)

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