Anticoagulation Therapy Flashcards by Love Roa

what is the first line of tx for sickle cell & what is the goal of therapy?

Hydroxyurea

reduce episodes of pain
reduce hospitalizations

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what is the dosing frequency for Hydroxyurea and what is the time frame for clinical response??

QD PO - weight based

> slow therapeutic response ~ 3-6 months

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what is the second line of tx for sickle cell and what are other treatments?

Second Line Tx: L-Glutamine (Endari): amino acid

monoclonal antibodies: Clavizunab
blood transfusions
stem cell transplant

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what anticoag blocks vitamin K and requires PT/INR monitoring?

Warfarin (Coumadin)

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what is a naturally occurring anticoagulant that inactivates thrombin and factor Xa?>

Heparin

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what new anticoagulants are considered pure factor Xa inhibitors?

Rivarobaxan (Xarelto)

Apixaban (Eliquis)

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what AC is a direct thrombin factor and what does it act on?

Dabigatran (Pradaxa) -> inhibits thrombin (factor IIa)

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what are clinical indications for Warfarin?

Afib -> PT/INR monitoring monthly

prophylactic or treatment of DVT & PE

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what are common side effects of Warfarin & which are the most worrisome?

fever
rash
diarrhea
hepatitis
*** hematuria -> indication of internal bleed
*** hemorrhage

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what is the dosing regimen for Warfarin and when must INR be monitored?

Initiation: 2-5mg qd x2-4 days
Check INR after 2nd or 3rd dose
Adjust dose based on PT/INR
After INR stabilizes, check INR BIW
INR checked monthly once therapeutic

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in what patients must you caution when they are prescribed warfarin?

elderly -> fall risk

patients w/ renal or hepatic failure -> more sensitive, watch CYP450

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what is the goal INR for warfarin?

therapeutic range: 2-3

goal: 2.5

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if a patient’s INR is > 3, what should be done?

hold Warfarin and recheck INR levels

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how many days does it take for warfarin to stabilize?

5-6 days

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what is the maintenance dose for warfarin?

2-10mg qd

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what is a rare reaction to warfarin that is seen in patients with protein C or S deficiency?

“purple/blue toes syndrome”

|&raquo_space;> due to microembolization of cholesterol, which occurs after several weeks to months of therapy

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aside from vitamin K, what is used for reversal of warfarin?

fresh frozen plasma

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what are drug interactions for warfarin & why does this happen?

Amiodarone
Alcohol
Cimetidine (Tagamet)
Disulfiram
Abx: Macrolides, tetracyclines, quinolones
Phenylbutazone
»> all are metabolized by Cytochrome P-450 system

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what drugs may increase INR levels in patients on warfarin?

Cephalosporins
Tetracyclines- Doxycycline 
Fluoroquinolones
Macrolides 
Bactrim
Glucocorticoids 
Omeprazole

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what drugs may decrease INR levels in patients on warfarin?

PCNs
Vitamin K
Carbamazepine
Phenobarbital
Dilantin/Phenytoin

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what are drug interactions for Heparin that may cause an additive AC effect?

PO anticoags
Salicylates & other antiplatelet drugs
> ASA
> NSAIDs: Ibuprofen, Naproxen

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what drug-herb can increase the risk of bleeding for heparin?

horse chestnut

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what are clinical indications for unfractionated Heparin and what is the major side effect?

DVT, PE, VTE prophylaxis

|&raquo_space;> Hemorrhage

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what is the MOA for unfractionated Heparin?

binds to antithrombin III -> inactivating factors IIa, IXa, Xa, XIa, and XIIa = thrombin complex
» fibrinogen goes not convert to form fibrin

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does the dose need to be adjusted for unfractionated Heparin in patients with renal insufficiency or renal failure?

no (therapeutic doses)

what is the half life of unfractionated Heparin and why is this important?

1-2 hours -> dose-dependent and may be disproportionately prolonged at higher doses *requires aPTT monitoring

what are adverse reactions for unfractionated Heparin?

``` #1: hemorrhage thrombocytopenia (HIT) white clot syndrome anaphylaxis fever ```

what is the tx of choice for VTE prophylaxis in patients with HIT?

Fondaparinux (Arixtra)

what can happen to a patient with HIT if they are given unfractionated heparin?

antibodies to platelets -> triggers thrombin generation -> venous or arterial thrombosis

what is the reversal used for unfractionated Heparin?

Protamine Sulfate

what are contraindications for Protamine Sulfate?

``` Hypersensitivity Any bleeding disorder Surgery of brain, eye, or spinal cord Intracranial Hemorrhage Infective Endocarditis Hx of HIT ```

what is the route of administration for unfractionated heparin and why is this important?

IV or SC -> hospital settings > cheaper > closer monitoring of aPTT

what is the dose for prevention of PE for unfractionated heparin?

5,000 units SC q 8 to 12 hours | *weight based when starting

what are the most common low molecular weight heparins (LMWH) and what is the freq of dosing?

Enoxaparin (Lovenox) | Dalteparin (Fragmin)

what are the advantages for using LMWH?

increased bioavility d/t long half life -decreased chance of induce thrombocytopenia -more predictable -> lab monitoring is not required *** outpatient therapy > preloaded syringe

what do LMWH primarily act on?

factor Xa - same as heparin but less binding

when is Lovenox indicated?

prevention of DVT, PE

why is Fondaparinux (Arixtra) used in patients with HIT (think of MOA)?

it is a synthetic selective factor Xa inhibitor with no antithrombin activity >> administered IV drip qd

what must be considered when dosing Fondaparinux (Arixtra)?

renal dosing >>> CrCl 30-50 caution is advised ***** CrCl < 30 contraindicated

why must a patient be started on Warfarin at least 5 days before discontinuing Heparin for outpatient treatment?

due to need for 5 day monitoring which allows warfarin to achieve full therapeutic effect

how are the DOACs get metabolized and what is their mechanism of action?

DOACs: Apixaban & Rivaroxaban Metabolized in liver >> directly inhibits factor Xa

what is the reversal for Apixaban and Rivaroxaban?

Andexxa | disadvantage: only available in hospital and is very expensive

what should you do if a pt on a direct oral anticoagulant starts to have bleeding and does not have access to Andexxa?

discontinue dose of DOAC

what are the advantages of direct oral anticoagulants over UFH & LMWH (vitamin K anticoagulants)?

PO administration onset: rapid predictable therapeutic effect-> no routine PT/INR *** short half-life

how many days must a DOAC be held prior to surgery?

3 days | * as opposed to 5 in LMWH & UFH

what are the disadvantages of new oral anticoagulants over VKAs?

1. no routine coag monitoring -> no awareness if pt is noncompliant and cannot titrate dose 2. short half-life -> less efficacy in non-compliant patients 3. antidotes are very expensive 4. may need dose adjustment for renal or hepatic dysfunction

what is the maintenance dosing for Apixaban (Eliquis)?

5mg BID PO

what is the VTE prophylaxis dose for Apixaban?

2.5mg BID

what is the maintenance dose for Rivaroxaban (Xarelto)?

20mg QD

What is the maintenance dose for Dabigatran (Pradaxa)?

150mg BID

In all newer oral anticoagulants, what must be considered?

renal dosing -> must check CrCl

if an 80 y/o M w/ afib weighs less than 60kg and has a Creatinine of 1.5, what should be done to their maintenance Eliquis dose?

- reduce Eliquis to 2.5mg BID OR - switch to Xarelto

what is considered in dosing Apixaban/Eliquis for afib patients?

age >>>>> 80 weight <<<< 60 kg Creatinine >>>>/= 1.5 *if pt has 2 out of 3 criteria -> must reduce dose to 2.5mg BID OR switch to Xarelto

what are the interactions for Apixaban (Eliquis)?

``` amiodarone antiplatelet meds carbamazepine phenytoin azole antifungals diltiazem rifampin macrolides: clarithromycin, erythromycin ```

in what situations would DVT prophylaxis be considered in starting temp anticoagulation therapy with Apixaban?

s/p TKR or total hip replacement

What are other newer anticoagulants indicated for stroke prevention and embolus with non-valvular afib?

Edoxaban (Sayvasa) | Betrixaban (Bevyxxa)

what is the maintenance dose for Dabigatran (Pradaxa) & what must be considered in patients?

150mg BID | -renal function

what is the MOA for Dabigatran (Pradaxa) and major side effect?

inhibits factor IIa | -bleeding

what is the reversal for Dabigatran (Pradaxa) & what is the benefit and disadvantage for it?

Praxbind/Idarucizumab benefit: 100% immediate effect con: very expensive

when initiating therapy of Rivaroxaban (Xarelto) for patients, what must you counsel them on?

increased risk for bleeding | >> must take w/ food

if switching a pt currently on Warfarin to Apixaban/Rivaroxaban, how should this be done?

discontinue warfarin and when INR is at 2, start Apixaban | *if INR < 2 -> can start right away

if switching a pt currently on Apixaban or Rivaroxaban to Warfarin, how should this be done?

start warfarin w/ 2-3 day overlap | -when INR is therapeutic on Warfarin, OK to d/c Xa inhibitor

when switching a pt currently on Heparin to direct oral ACs, is there overlap when starting?

Anticoagulation Therapy Flashcards

(63 cards)