Heparin

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rINN: Heparin
Other Names
UFH, Calciparine®,Monoparin®, Monoparin Calcium®, Multiparin®
Pharmacological Information
Web information on Heparin
Metabolism & Interactions
Binding to endothelial cells and clearance by reticuloendothelial cells which is saturable, and a nonsaturable mechanism mainly by kidney
Mechanism of Action
Specific pentasaccharide sequence, which binds with high affinity to antithrombin and potentiates its activity
Other Issues for Heparin
Renal clearance predominates with LMWH
Relevant Clinical Literature
UK Guidance
Regulatory Literature
Other Literature
Other Wikis
Wikipedia on Heparin (Less technical, ? quality control)

Heparin is a sulfated glycosaminoglycoside polymer of alternating chains of uronic acid and glucosamine, It can be:

  1. unfractionated (UFH), i.e. chains of various lengths with a molecular weight (MW) range of 5000–35 000 Da and mean MW of about 13 000–15 000 Da. There are several commercial preparations which are not equivalent (see box to right) .
  2. low molecular weight (LMWH), consisting of more uniform shorter chains. Each commercial preparation has slightly different properties. See low molecular weight heparins .

Acts via antithrombin.

Monitored by:

Contents

Clinical Use

Indications

Anti-coagulation in:

Flag of the United Kingdom.png

British guidelines on the use of heparin in all indications have been published in 2006[1]

Administration

Parenteral only: s.c.

  • UFH for prophylaxis of VTE: 5000 units b.d./t.d.s.
  • LMWH depends on product

i.v.

Clinical Issues

UFH is not the same as LMWH clinically, and the greater convenience of LMWH and safety profile in routine practice has seen LMWH replace UFH for most indications. However UFH still has a place, but requires intensive monitoring at treatment rather than prophylaxis doses with individual dosage adjustment based on APPT. That clinical staff have become unskilled in giving it is a poor reason not to use it in circumstances where it may be the safest effective drug such as in bariatric (morbid obesity) patients.

Toxicity

LogoKeyPointsBox.pngReversing Heparin
  • 1mg of protamine reverses 80-100 units of recently given heparin
  • heparin has a short half life, the required protamine dose falls quite quickly

Contra-indications

Cautions and Interactions

Renal clearance predominates for LMWHs with increasing haemorrage risk in renal failure.

Side effects

Special advice

There is no evidence that UFH or LMWHs cross the placenta so they are presently the anticoagulants of choice in pregnancy.

Pharmacology

  • All heparins presently used in UK come from porcine sources.
  • UFH heparin can be a sodium or calcium salt. They have different properties.
  • Most LMWHs are sodium salts (fraxiparine -Nadroparin®),is a calcium salt).
  • Low-molecular weight heparins have longer half-lives than UFH.
    • In vivo there are differences in some indications, and dose must be right for indication.

Contamination

During 2008 oversulphated chondroitin sulphate adulterated heparin supplied worldwide from a single source in China leading to several deaths[2].

References