T H R O M B O T I C . . D I S O R D E R S . . C H R O N I C . . T X

W A R F A R I N - - - ( C O U M A D I N )
1. Monitoring: Must be monitored regularly
  1. Testing
    1. INR (International Normalized Ratio)
      1. Normal = 0.9 - 1.2
      2. Goals are based on indication for therapy
        Goal = 2 - 3
        DVT/PE, aFIB, Cardioembolic stroke, BIOPROSTHETIC VALVES, & mechanical AORTIC bileaflet valve (in NSR, normal EF)
        Goal = 2 . 5 - 3 . 5
        Mechanical tilting disk or caged ball (aortic or mitral) OR mechanical mitral bileaflet valve
      3. R I S K S
        INR < 2 = RISK OF CLOTTING
        INR > 3 = RISK OF BLEEDING
    2. CBC (Complete Blood Count)
      1. Hemaglobin
        Normal: 12-16 g/dL (F) & 14-18 g/dL (M)
      2. Hematocrit
        Normal: 36-45% (F) & 42-50% (M)
  2. Frequency
    1. Inpatient = Daily
    2. Outpatient (Initially) = weekly, every other week, then once monthly
      1. Outpatient (Once Stable) = every 4 - 12 weeks (most common = monthly)
  3. How?
    1. Venous Blood Draw
    2. Point of Care Device (similar to glucometer)
2. Dosing
  1. Inpatient
    1. Level I
      1. 2 . 5 mg
      2. Patient starts here if the meet any of the criteria
        Age > 74, Weight < 54.5 kg, CHF, liver disease, ESRD, Hyperthyroidism, malnourished/NPO for > 3 days, high risk of bleeding
        SEVERE DRUG-DRUG INTERACTIONS!
        Amiodarone, Bactrim, Metronidazole (Flagyl), -Azoles (fluconazole, ketoconazole), cimetidine
    2. Level II
      1. Normal starting dose UNLESS patient meets criteria for other levels
      2. 5 mg
    3. Level III
      1. 7.5 mg
      2. Patient starts here if weight is > 91 kg AND age < 60 years
  2. Maintenance
    1. Approach
      1. 1. Evaluate any rationale for high or low readings (ex: med changes, missed doses, illnesses)
        2. Calculate weekly dose and check iNR
        3. Adjust if out of goal range => change by 5-20%
    2. Repeat Monitoring
      1. When Unstable (Includes changing dose) = every 1-2 weeks
      2. When Stable: Every 4 weeks - - guidelines suggest every 12 weeks for long-term stable patients
  3. Formulation = Tablets - - Only select ONE strength tablet
  4. QD Dosing - same time every day
3. S U M M A R Y
  1. PROS
    1. Historical product with much experience in practice
    2. INR test allows for assessment of efficacy
    3. Readily reversible
    4. Broader indications
    5. Cost
  2. CONS
    1. Frequent follow-up is required
    2. Many drug & herbal interactions
    3. Diet considerations must be made
    4. Must be bridged
  3. MOA
    1. Vitamin K Antagonist
    2. Inhibits clotting factors II, VII, IX, & X
      1. Also inhibits proteins C & S
      2. These factors are Vitamin K dependent
    3. Bridging with IV is necessary bc not all factors are affected at the same time
  4. Indications
    1. VTE, aFIB, Stroke, Valve Replacement
  5. Interactions
    1. MANY
    2. BOTH food and drugs
  6. Counseling
    1. Must be consistent with Vit K containing foods
  7. Reversal ?
    1. Yes
      1. INR = 3 . 6 - 10 WITHOUT bleeding
        Monitor more closely
        Hold warfarin until INR decreases
        Look for causes and address
        Restart at a lower dose
        Vitamin K is not recommended
      2. INR > 10 WITHOUT bleeding
        Hold warfarin until INR decreases
        Give VIT K 5 mg PO
        Identify Causes
        Re-start at a lower dose
      3. ANY INR WITH bleeding
        Hold warfarin - - rapid reversal required
        Four - Factor Prothrombin Complex Concentrate (PCC)
        P L U S
        VIT K 5 - 10 mg IV
  8. Metabolism
    1. R - Enantiomer = CYP3A4
    2. S - Enantiomer = CYP2C9 (More Potent)
4. ADRs
  1. Bleeding
    1. Prolonged clotting time with cuts
    2. Bleeding Gums
    3. Epistaxis (AKA Nose Bleeds)
    4. BRBPR (Bright Red Blood Per Rectum)
    5. Hematochezia (Passage of blood through the rectum)
    6. Hematuria (Blood in urine)
    7. Melena (Dark Tarry Stools)
    8. Coffee-Ground emesis (Indicates upper GI Bleeding)
  2. Bruising
    1. Will occur more easily
    2. Problem when they grow in size, fail to heal, or are unexplainable
  3. Altered Mental Status
    1. Significant confusion or sudden severe headache
    2. May indicate intracranial bleeding
  4. Purple Toe Syndrome
    1. Dark blue discoloration of toes with burning pain
    2. generally occurs 3-8 weeks after initiation
  5. Skin Necrosis
    1. Damaged tissue resulting in pain, rash and necrotic tissue commonly affecting the thighs, buttocks, and breasts
    2. Generally occurs within the first 10 days of treatment
5. Interactions
  1. Disease States
    1. Decreased INR
      1. Hypothyroidism
      2. Smoking
    2. Increased INR
      1. Diarrhea/Vomiting, Fever/Infection
      2. CHF, Liver Disease
      3. Hyperparathyroidism
  2. Drug Interactions
    1. Increased INR
      1. Severe DDIs: Amiodarone, Bactrim, Metronidazole, Azoles, Cimetidine
    2. Decreased INR
      1. Barbiturates, Carbamazepine, Cholestyramine, Chronic Alcohol Intake, Rifampin, Vitamin K
    3. Increased Bleeding Risk
      1. Aspirin, Clopidogrel, Dipyridamole, Fish Oil, NSAIDs, Ticlipidine
  3. Food Interactions
    1. Decrease INR
      1. Eating more VIT K
    2. Increase INR
      1. Eating less Vit K than normal
D A B I G A T R A N - - - ( P R A D A X A )
1. S U M M A R Y
  1. MOA - DIRECT THROMBIN INHIBITOR
  2. INDICATIONS - VTE, NONVALVULAR ATRIAL FIBRILLATION, & STROKE
  3. DOSE - BID
  4. ADRs - BLEEDING, GI UPSET & DYSPEPSIA
  5. MONITORING: ECT, TT, aPTT CAN BE USED BUT NOT MONITORED REGULARLY
  6. INTERACTIONS
    1. DRUGS - YES
    2. NO FOOD INTERACTIONS - TAKE WITHOUT REGARD TO FOOD
  7. COUNSELING - KEEP IN ORIGINAL CONTAINER
  8. REVERSAL AGENT - YES, BUT THERE IS A CONCERN WITH EFFECTIVENESS
2. D O S I N G
  1. BY INDICATION
    1. V T E - (DVT OR PE TREATMENT)
      1. STANDARD DOSE - 150 MG BID (AFTER 5-10 DAYS OF PARENTERAL ANTICOAGULATION)
      2. RENAL DOSAGE CHANGES
        CRCL: 31-50 ML/MIN
        IF ON P-GP INHIBITORS, AVOID USE!
        CRCL < 30 ML/MIN
        CONTRAINDICATED !!
    2. ATRIAL FIBRILLATION (NONVALVULAR)
      1. DOSE - 150 MG BID
      2. RENAL DOSAGE CHANGE
        > 50 ML/MIN
        NO ADJUSTMENT NEEDED
        31 - 50 ML/MIN
        ONLY DOSE ADJUST IF CERTAIN DDI'S ARE PRESENT
        ALSO IF ON DRONEDARONE OR KETOCONAZOLE
        THIS IS JUST AN ESTIMATE - - NO CLINICAL STUDY WAS PERFORMED - - SKEPTICAL
        DOSE - 75 MG BID
        CRCL 15 - 30 ML/MIN
        DOSE - 75 MG BID
        AVOID IF TAKING DRONEDARONE, KETOCONAZOLE, OR P-GP INHIBITORS
        CRCL < 15 ML/MIN
        CONTRAINDICATED !!
  2. MISSED DOSES
    1. TAKE AS SOON AS YOU REMEMBER
    2. ONLY SKIP IF NEXT DOSE IS WITHIN 6 HOURS
  3. FORMULATIONS
    1. ORAL CAPSULES
      1. TAKE WITHOUT REGARD TO MEALS
      2. DO NOT OPEN OR CHEW CAPSULES
      3. TAKE WITH WATER
      4. KEEP IN ORIGINAL CONTAINER
      5. DISCARD AFTER 120 DAYS AFTER OPENING
    2. NO IV PRODUCT AVAILABLE
3. C O N T R A I N D I C A T I O N S
  1. HYPERSENSITIVITY, ACTIVE BLEEDING, PROSTHETIC HEART VALVES, CRCL < 30 ML/MIN
4. MONITORING
  1. NO REGULAR MONITORING REQUIRED
  2. AVAILABLE TESTS
    1. ECARIN CLOTTING TIME (ECT)
    2. ACTIVATED PARTIAL THROMBOPLASTIN TIME (aPTT)
    3. THROMBIN TIME (TT)

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	Created by Kaytlynn Fisher almost 6 years ago