[Preliminary study of the use of low-molecular weight heparin to prevent thrombotic risk].

This study involved two stages: In vitro study. Three LMWHs, CY 216-CY 222 (Choay) and PK 10169 (Pharmuka), were compared to standard heparin, SH (Choay), and to a high-molecular-weight heparin, HAF (Choay), which particularly revealed a dissociation of anti-Xa (++) and anti-IIa (+) activities for the LMWHs: (table: see text) In vivo study. Healthy volunteers. Subcutaneously injections of PK 10169 or CY 222 according to various protocols (rythm of injections, dosage). For both LMWHs, the dissociation of anti-Xa and anti-IIa activities reoccurs in vivo. A peak of anti-Xa effect was observed 3 to 4 hours after the injections. The duration period of this activity is about 12 hours. The importance of the global platelet tests HT and TEG (modified for the highest doses) should be noted. Study of haemorrhagic tendencies in patients with slight thrombotic risk. From this preliminary study, protocols with CY 216, CY 222 and PK 10169 are proposed for the prevention of thrombotic risk in orthopaedic surgery (injections at 12-hour intervals).