Effects of heparin and a semi-synthetic heparin analogue on platelet aggregation, lipoprotein lipase and other laboratory tests in surgical patients

An Objective Assessment of the Interaction of Heparin and Its Fractions with Human Platelets

“…In addition to the ability to produce thrombocytopenia, in vivo, heparin has also been shown to cause platelet aggregation in vitro, independent of the involvement of an antibody. [11][12][13]27,29,35,37,38 However, the mechanism of heparin-induced platelet aggregation has remained controversial. Different investigators have obtained varying results, ranging from heparin-induced aggregation, to potentiation of aggregation induced by other agents, to no observed effect, or to an actual inhibition of platelet aggregation.…”

“…Different investigators have obtained varying results, ranging from heparin-induced aggregation, to potentiation of aggregation induced by other agents, to no observed effect, or to an actual inhibition of platelet aggregation. 8,19,22,28,29,[35][36][37][38] Table 1 illustrates some of the problems associated with interpretation of the reported results. First, the platelet system used varies.…”

Biochemical and Pharmacological Studies on the Interaction of PK 10169 and Its Subfractions with Human Platelets

“…Previous reports in the literature have in dicated that addition of heparin to platelets in vitro causes platelet aggregation [20][21][22][23]. However, others have not reproduced these results [24] or have obtained inconsistent re sults [25].…”

“…These thrombi are composed primarily of fibrinplatelet aggregates [14], Many of these pa tients require increasing doses of heparin to maintain therapeutic levels of anticoagula tion, and it has been suggested that increased heparin tolerance may prcceed clinical signs associated with HIT [3,4,8], This type of thrombocytopenia appears to be independent of the source, dosage and route of adminis tration of heparin [3,4,9,12,[15][16][17], A less commonly observed complication of heparin administration is heparin-induced platelet activation [18][19][20][21][22][23], This type of hep arin-platelet interaction may be involved in some reported cases of arterial thrombosis associated with heparin administration and also in the cases of thrombocytopenia that are observed shortly after heparin therapy has been instituted [15,16], In these cases, the thrombocytopenia may be mild, or the platelet count may drop below 100,000/pl; the decrease in the platelet count being ob served within hours to 3 days after heparin administration has begun. The immune sys tem does not appear to be involved.…”

Molecular Weight of Heparin Versus Biologic Activity Some Additional Considerations

“…Messmore et al 37 isolated an immunoglobulin G (IgG) fraction from the serum of a patient with heparin-induced thrombocytopenia; they showed that heparin, down to an octasaccharide, resulted in positive platelet aggregation when tested using serum of these patients. On the other hand, Torngren and his colleagues 49 found that there was no difference between semisynthetic heparin analogues and standard heparin in thrombocytopenic effects of their surgical patients. Bjork et al 6 found that low molecular weight heparins prevented thrombus formation in similar fashion to conventional heparin in a rabbit model without influencing primary hemostasis.…”