Heparin is a naturally occurring glycosaminoglycan from livestock,
principally porcine intestine, and is clinically used as an
anticoagulant drug. A limitation to heparin production is that it
depends on a single animal species and potential problems have been
associated with animal-derived heparin. The contamination crisis in 2008
led to a search for new animal sources and the investigation of
non-animal sources of heparin. Over the past 5 years, new animal
sources, chemical, and chemoenzymatic methods have been introduced to
prepare heparin based drugs. In this review, we describe advances in the
preparation and synthesis of heparin and related products
