Abstract

 An international, multi-centre trial was carried out to test the haemorheological effects of ketanserin, a serotonin antagonist, after treatment of intermittent claudicants for 1 year. Haematological indices, whole blood viscosity, plasma viscosity and red cell and white cell     filterabi1ity were measured using standardised techniques. Even so, inter-laboratory variability, and intra-laboratory changes in control values in some centres over the 1 year period proved to be major obstacles. The pooled data showed no evidence of haemorheological changes, although data from the single largest centre indicated slightly lowered haematocrit and blood and plasma viscosity. Any rheological effects of serotonin antagonists in intermittent claudicants are probably small and unlikely to be the main source of any clinical efficacy. In general, it would appear that standardisation and monitoring of laboratory techniques must be strictly carried out if there is to be any hope of successfully carrying out multi-centre haemorheological trials. .

 Key words: Blood Rheology; Claudication; Serotonin Antagonists;