heparin

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[1][2][3][4][5][6][7][8][9][10]

Function

In intact tissue, heparin is confined to mast cells where it is stored in cytoplasmic granules[1]. It serves to neutralize positive charge of histamine within the granules.

Structure

Heparin has the highest density of negative charge of any biological macromolecule[2]. It is composed of alternating sulfated (2,6)-glucosamine & glucuronate-2-sulfate residues (1,4 alpha linkage). Iduronate & its 2-sulfate are present in variable amounts. Heparan sulfate is like heparin, but contains fewer N- & O-linked sulfates (1,4 alpha linkage). The core protein of heparin is exclusively serglycin in contrast to heparan sulfate which contains a variety of core proteins (see heparan sulfate).

Compartment

cytoplasmic granule

Expression

mast cell

Indications

* LMW heparin is better than unfractionated heparin except if emergent surgery or thrombolysis is planned

Contraindications

Caution:

* variations in the bioavailability of unfractionated heparin result in a delays in attaining therapeutic levels vs LMW heparin[9]

Dosage

aPTT rate change additional action
<45 sec + 6 mL/hr rebolus with 5000 U
45-54 sec + 3 mL/hr none
55-85 sec none none
86-110 sec - 3 mL/hr stop infusion 1 hr > 110 sec - 6 mL/hr stop infusion 1 hr

Injection: 1000 units/mL (1 mL, 10 mL, 30 mL) 5000 units/mL (1 mL) 10,000 units/mL (1 mL, 4 mL) 20,000 units/mL (1 mL)

Solution: (lock flush) 10 units/mL (1 mL Tubex) 100 units/mL (1 mL Tubex, 10 mL vial)

* in patients for whom heparin is initiated for anticoagulation, & titration to therapeutic effect is difficult, consider antithrombin-3 deficiency

Pharmacokinetics

Monitor

*anti-factor Xa heparin assay instead of aPTT

Adverse effects

Drug interactions

Laboratory

interactions

Mechanism of action

Notes

  • isolated on a commercial basis from pig intestinal mucosa & bovine lung.
  • effective October 1, 2009, a change, which will also harmonize the USP unit dose with the WHO International Standard unit dose, will result in approximately a 10% reduction in the potency of the heparin marketed in the United States.[6]
  • total drug strength of entire container on label required by FDA[7]

More general terms

More specific terms

Additional terms

References

  1. ↑ Jump up to: 1.0 1.1 Salmivirta M, Lidholt K, Lindahl U. Heparan sulfate: a piece of information. FASEB J. 1996 Sep;10(11):1270-9. Review. PMID: https://www.ncbi.nlm.nih.gov/pubmed/8836040
  2. ↑ Jump up to: 2.0 2.1 Drug Information & Medication Formulary, Veterans Affairs, Central California Health Care System, 1st ed., Ravnan et al eds, 1998
  3. ↑ Kaiser Permanente Northern California Regional Drug Formulary, 1998
  4. ↑ Jump up to: 4.0 4.1 4.2 4.3 4.4 Medical Knowledge Self Assessment Program (MKSAP) 11, 16, 17, 18, 19. American College of Physicians, Philadelphia 1998, 2012, 2015, 2018, 2022.
  5. ↑ Jump up to: 5.0 5.1 FDA Medwatch http://www.fda.gov/medwatch/safety/2006/safety06.htm#Heparin
    Prescriber's Letter 15(5): 2008 Heparin Contamination and Shortage Detail-Document#: http://prescribersletter.com/(5bhgn1a4ni4cyp2tvybwfh55)/pl/ArticleDD.aspx?li=1&st=1&cs=&s=PRL&pt=3&fpt=25&dd=240512&pb=PRL (subscription needed) http://www.prescribersletter.com
  6. ↑ Jump up to: 6.0 6.1 FDA MedWatch Heparin: Change in Reference Standard http://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm184687.htm
  7. ↑ Jump up to: 7.0 7.1 FDA MedWatch: 12/06/2012 Heparin: Drug Safety Communication - Important change to heparin container labels to clearly state the total drug strength http://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm331168.htm
  8. ↑ Jump up to: 8.0 8.1 8.2 8.3 Deprecated Reference
  9. ↑ Jump up to: 9.0 9.1 9.2 Medical Knowledge Self Assessment Program (MKSAP) 18, 19. American College of Physicians, Philadelphia 2018, 2022.
  10. ↑ Jump up to: 10.0 10.1 NEJM Knowledge+ Hematology
    Guervil DJ, Rosenberg AF, Winterstein AG et al Activated partial thromboplastin time versus antifactor Xa heparin assay in monitoring unfractionated heparin by continuous intravenous infusion. Ann Pharmacother. 2011 Jul;45(7-8):861-8 PMID: https://www.ncbi.nlm.nih.gov/pubmed/21712506

Database

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