HEMATOLOGY, ONCOLOGY, ALLERGY,
AND IMMUNOLOGY
CONTRAINDICATIONS
■ Hypersensitivity, active GI bleeding, intracranial hemorrhage, current bac-
terial endocarditis, heparin-induced thrombocytopenia (HIT)
DOSING
■ Bolus 70–80 units/kg IV followed by infusion 15–18 units/kg/hour
MONITORING
■ Follow aPTT and titrate based on therapeutic range (usually 1.5–2.5 ×the
normal value).
COMPLICATIONS
■ Major bleeding
■ HIT syndrome (autoimmune response to heparin →low platelets, thrombosis)
REVERSAL
■ Stop heparin—short half-life
■ Protamine sulfate, 1 mg IV for every 100 units of heparin, over the previous
four hours to a maximum of 50 mg
Low-Molecular-Weight Heparin
Inhibits activity of factor Xa; includes enoxaparin, dalteparin, ardeparin
TABLE 9.10. Medications Affecting INR
INCREASEINR DECREASEINR
Allopurinol, amiodarone, azithromycin, cimetidine, Carbamazepine, cholestyramine,
clotrimazole, fluroquinolones, INH, metronidazole, dicloxacillin, griseofulvin, haloperidol,
omeprazole, penicillin, phenytoin, prednisone, nafcillin, ranitidine, rifampin
propoxyphene, quinidine, statins, sulfonyureas,
tetracycline, tamoxifen, zafirlukast
TABLE 9.11. Warfarin Reversal
INR BLEEDING TREATMENT
< 5 No Hold dose, recheck INR in 24 hours
5—9 No Hold dose, consider oral vitamin K 1—2 mg PO, recheck
INR in 24 hours
> 9 No Hold dose, vitamin K 2—4 mg PO, recheck INR in 24 hours
Any elevation Major bleeding Hold dose, FFP transfusion or factor concentrates, vitamin
K 5—10 mg slow IV or sub Q
Any elevation Minor bleeding Hold dose, vitamin K 2—4 mg PO
HIT syndrome is less common
with low-molecular-weight
heparin (LMWH) than with
heparin. In patients with HIT,
stop the heparin or LMWH
and start a direct thrombin
inhibitor.