Allopurinol prevents ischaemia-dependent haemorheological changes.

Pre-treatment with allopurinol is able markedly to attenuate the deterioration in blood viscosity (BV) and whole blood filterability (WBF) that occurs after ischaemia during exercise. It also reduces the exercise-induced increase in serum oxidase activity, although this action is slightly less effective in peripheral obliterative arterial disease (POAD) patients. Conversely, allopurinol is completely ineffective in modifying haemorheological parameters in vitro, and it does not affect superoxide anion generation or enzyme release from neutrophils stimulated in vitro with formyl-methionyl-leucyl-phenylalanine (FMLP). It is suggested that allopurinol may attenuate changes in BV and WBF by affecting xanthine-oxidase-dependent free radical formation in tissues.