Strategies to overcome heparins’ low oral bioavailability

Even after a century, heparin is still the most effective anticoagulant available with few side effects. The poor oral absorption of heparins triggered the search for strategies to achieve oral bioavailability since this route has evident advantages over parenteral administration. Several approaches emerged, such as conjugation of heparins with bile acids and lipids, formulation with penetration enhancers, and encapsulation of heparins in micro and nanoparticles. Some of these strategies appear to have potential as good delivery systems to overcome heparin’s low oral bioavailability. Nevertheless, none have reached the market yet. Overall, this review aims to provide insights regarding the oral bioavailability of heparin. © 2016 by the author; licensee MDPI, Basel, Switzerland.This work was supported by ERDF, COMPETE, and FCT under the Strategic Funding UID/Multi/04423/2013, projects PTDC/MAR–BIO/4694/2014 and PTDC/AAG–TEC/0739/2014, and INNOVMAR–Innovation and Sustainability in the Management and Exploitation of Marine Resources, reference NORTE–01–0145–FEDER–000035, Research Line NOVELMAR