Cross-reactivity study of low molecular weight heparins and heparinoid in heparin-induced thrombocytopenia.
Previous studies suggested that the cross-reactivity rates of low molecular weight (LMW) heparins with the antibody in heparin-induced thrombocytopenia (HIT) are more than 80%, whilst that of the LMW heparinoid (Orgaran) is relatively low at about 10%. These earlier studies were limited either in the number of patients studied, or in investigating only a single drug. They were also inadequate due to non-standardisation of testing conditions. This study compares three LMW heparins (Fragmin, Clexane, Fraxiparin) and a heparinoid (Orgaran) in their cross-reactivity rates with the HIT antibody. The sera of 45 HIT patients were tested using platelet aggregometry under standardised conditions. The cross-reactivity rates are: 7% (Orgaran), 89% (Fragmin), 83% (Clexane) and 86% (Fraxiparin). Although there are no controlled trials to determine the in vivo cross-reactivity rates of LMW heparins and heparinoid, the low in vitro cross-reactivity rate of the latter favours its use in HIT. Nevertheless, the therapeutic use of these drugs in HIT should be preceded by exclusion of in vitro cross-reactivity.
Department of Haematology, Prince of Wales Hospital, Sydney, New South Wales, Australia.
C M
CM
Vun
S
S
Evans
B H
BH
Chong
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003429:Cross Reactions; D005260:Female; D006495:Heparin, Low-Molecular-Weight / Q000009:adverse effects* / Q000276:immunology; D006496:Heparinoids / Q000009:adverse effects* / Q000276:immunology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation; D013921:Thrombocytopenia / Q000097:blood / Q000139:chemically induced*
D006495:Heparin, Low-Molecular-Weight; D006496:Heparinoids