COMPARISON OF VARIOUS AMI DOLYTIC HEPARIN ASSAYS: REPORT OF A COLLABORATIVE STUDY

The authors performed a controlled study to compare commercially available amidolytic heparin assays based on anti-Xa or anti-I la systems. All participants (see below) were provided with the same batch of all heparin preparations and reagents including homogenous plasma preparation. In addition plasma was spiked with the various unfractionated (n=2) as well as lmwh- (n=5) and heparinoid preparation (n=l). The four university laboratories analyzed all heparin preparations that are registered or used in clinical trials in FRG (n=8). The two testkit producers analyzed registered heparin preparations and the heparin producer their brand only. The study was recently completed and the data analysed and collected. The first evaluation revealed that the amidolytic anti-I la assay is insensitive for lmwh and heparinoids. Determination of unfractionated heparins is not accurate below 0.5 units of the corresponding standard. The Xa-methods are more sensitive for lmwh and heparinoids, however these methods also reveal a high standard deviation. Estimation of concentrations below 0.5 units of all tested heparin preparations is questionable.

The authors are indented for active cooperation to Prof. Dr. K. Andrassy (Med. Univ. Heidelberg), Dr. M. Biegholdt (MIDY LABAZ), Dr. G. Dertinger (Sandoz AG), Dr. VJ. Feller (Braun Melsungen AG), Dr. P. Friberger (Kabi Vitrum Stockholm), Dr. P. Hell stern (Univ. Klinik Homburg), Dr. D. G. Meulemann (Organon Scientific Development Group), Dr. X. Muller (Nordmarkwerke), Dr. Zimmer (Boehringer Mannheim GmbH).