Drug Modification of Erythrocyte Deformability

Abstract

There has been no significant advance in the treatment of peripheral circulatory insufficiency since reconstructive arterial surgery became generally accepted over 20 years ago. The next breakthrough, as well as the final solution, is almost certainly going to be non-surgical. Less than 20% of patients with peripheral ischaemia, whether in the limbs or the brain, are suitable for surgical treatment and even in this highly selected group the results are discouraging. Nor is there any indication that either the scope or the success of this approach is likely to improve in the near future. Medical attempts at treatment have concentrated on the removal of risk factors and the prevention of thrombosis by anti-platelet drugs. But another avenue which, in the short term at least, may well prove more profitable to explore is haemorheological manipulation, by which it is hoped to improve the flow properties of blood. Although this would leave the vessel disease untouched, it could probably produce more rapid and dramatic results in terms of improving tissue perfusion. Haemorheological therapy may rather artificially be divided into treatment aimed at improving blood viscosity or improving the flow properties of the individual red cells. This distinction is purely artificial as undoubtedly one of the most important determinants of whole-blood viscosity, particularly at high shear rates, is the ability of individual red cells to deform. This chapter will, however, only consider the action of drugs specifically on erythrocyte deformability.