Heparin

Heparin Unfractionated (UFH)

Class:
  • Anticoagulant
Actions:
  • Facilitates antithrombin in inactivating thrombin and clotting factor Xa
Indications:
  • Unstable angina (UA) and non-ST segment elevation MI (NSTEMI)
  • Adjunct to fibrinolytic therapy
  • Pulmonary embolism
  • evolving thrombotic stroke (CVA)
  • Deep vein thrombosis
  • Extracorporaeal circulation associated with hemodialysis or ECMO during cardiac surgery
  • Disseminated intravascular coagulation (DIC)
Pharmacokinetics:
  • Onset: 20 – 60 minutes (SQ)
  • Peak: immediately (IV)
  • Half-Life: 1.5 hours
  • Duration:  2 – 6 hours (IV); 8 – 12 hours (SQ)
Adverse Effects:
  • Spontaneous bleeding
  • Transient thrombocytopenia
  • Hypersensitivity (chills, fever, urticaria, hives, pruritis, bronchospasms, anaphylaxis)
  • Osteoporosis, hypoaldosteronism, hyperkalemia (long-term use)
  • Injection site reactions
Contraindications:
  • Thrombocytopenia (Platelet count < 100,000)
  • Uncontrolled bleeding
  • Recent intracranial, intraspinal, or eye surgery
  • Lumbar puncture or regional anesthesia
  • History of hypersensitivity
  • Bleeding tendencies like hemophilia
  • Severe hypertension
  • Continuous tube drainage from stomach or intestines
  • Active tuberculosis
  • Ascorbic acid deficiency
  • Advanced kidney or liver or pancreatic disease
  • Cautious use in alcoholism, menstruation, indwelling catheters
  • Caution with pregnancy (Category C) especially 3rd trimester & postpartum
Dosages & Routes:
  • Intravenous: bolus 60 units/kg (maximum bolus 4,000 units for ACS; 5,000 units otherwise)
  • Intravenous Infusion:  12 units/kg/hour (around 1,000 units/hour)
  • Subcutaneous:  1st dose: 10,000 – 20,000 units;  subsequent doses: 8,000 – 20,000 units every 8 – 12 hours
Nursing Implications:
  • Drug Interactions:  1) Aspirin, NSAIDS, oral anticoagulants, and anti-platelet drugs may increase the risk of bleeding; 2) feverfew, ginkgo, ginger, and valerian may increase the risk of bleeding; 3) Nitroglycerin may decrease the anticoagulant effect of heparin; 4) Protamine sulfate is an antagonist to heparin.
  • Drug Incompatibilities: Do not mix IV line with any other medications.  There is a long list of incompatibilities.
  • Protamine sulfate is the antidote for overly anticoagulated dose of heparin. (1 gm protamine inactivates 100 units heparin).
  • Heparin drip should be continuous.  Do not  interrupt a heparin drip for any other drug or IV therapy. Short half-life:  If infusion is turned off, therapeutic effect can be lost.
  • Only routes of administration are IV or SQ (does not absorb PO; IM causes hematoma)
  • Risk of bleeding increases.  Screen patients for contraindications.
  • To reduce risk of hemorrhage, dosage must be monitored closely and adjusted according to aPTT levels.
  • Monitor with activated partial thromboplastin time (aPTT) which normally is around 40 seconds.
  • Therapeutic goal for aPTT is 1.5 – 2 Ï normal level = 60 – 80 seconds).
  • Draw blood for aPTT 30  minutes before SQ or intermittent doses of heparin.
  • Does not cross placental barrier during pregnancy or pass into breast milk during lactation.
  • Monitor injection sites for signs of hematoma.
  • Apply direct pressure to venipuncture sites for longer durations (e.g., 3 minutes).
  • Low molecular weight heparin (e.g., enoxaparin) is preferred for unstable angina and NSTEMI over unfractionated heparin.

 

References:

American Heart Association. (2006). Handbook of Emergency Cardiac Care (p. 55). Salem, MA: AHA.

American Heart Association. (2005).  2005 AHA guidelines for cardiopulmonary resuscitation and emergency cardiac care: Stabilization of the patient with acute coronary syndromes. Circulation, 112(24 Supple.), IV 89-110.

Lehne, R.A. (2010). Pharmacology for nursing care (7th ed., pp. 594-618).  St. Louis: Saunders Elsevier.

Wilson, B.A., Shannon, M.T., Shields, K.M., & Stang, C.L. (2007).  Prentice Hall Nurse's Drug Guide 2007 (pp. 793-796).  Upper Saddle River, NJ: Pearson Prentice Hall.

 

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