Diltiazem alters blood rheology.

A study was carried out to investigate whether diltiazem influence blood rheology, as has been reported for some other calcium channel blockers. Twenty patients with clinical, stable angina pectoris were treated with 2 x 90 mg diltiazem per day for 2 weeks. Blood viscosity, plasma viscosity, haematocrit, blood cell filterability and red cell aggregation were taken as in vitro measures quantifying the flow properties of blood. After 1-week's treatment, low and middle shear blood viscosity had declined significantly. This change was more pronounced after 2-weeks' medication. At this point, there was also an increase in blood cell filterability. All other variables did not show significant alterations. The results suggest a significant fluidification of blood during diltiazem treatment. This effect may reduce the viscous component of the total peripheral resistance, and therefore, it may contribute to an increase in perfusion and to the anti-anginal properties of the drug.