A new low molecular weight heparin fragment (PK 10169): in vitro and in vivo studies.

The depolymerized heparin fragment PK 10169 was compared with unfractioned mucosal sodium heparin. The inhibition of factors Xa and IXa by heparin and by PK 10169 was comparable on a weight base, whilst the inhibition of thrombin by PK 10169 was at least 5 times weaker than by heparin. Subcutaneous injection of PK 10169 was not followed by an increase of the thrombin time. The activated partial thromboplastin time was considerably less prolonged after PK 10169 than after heparin. Platelet count and platelet functions were not influenced by PK 10169. In vitro, the euglobulin lysis time (ELT) was shortened after addition of heparin to plasma but not after addition of PK 10169. After injection however, there was an equal shortening of the ELT by both substances. The half-life in circulation of PK 10169 was longer than the half-life of heparin. The advantages of PK 10169 over heparin are therefore the weaker influence on overall coagulation, the missing influence on platelet functions and the longer half-life in circulation.