The inhibition of lipid peroxidation by cinnarizine. Possible implications to its therapeutic and side-effects.

Cinnarizine has antivasoconstrictor properties and improves red-cell deformability. Its major side-effects are the induction of extrapyramidal reactions. It is a calcium antagonist, but it was suggested that its effects may depend on other mechanisms, namely on antiperoxidant properties. We have studied these properties in different biological systems, intact red-cells included. The occurrence of lipid peroxidation was determined by the formation of 2-thiobarbituric acid reactive products. Cinnarizine was found to inhibit spontaneous lipid peroxidation in rat liver homogenates, copper-induced lipid peroxidation in human plasma and copper-induced and hydrogen peroxide-induced lipid peroxidation in human red-cells. In red-cells, the inhibition of lipid peroxidation is accompanied by the inhibition of hemolysis. Copper-induced red-cell lipid peroxidation is 85% inhibited by as little as 5 microM cinnarizine. The antioxidant activity of cinnarizine may contribute to explain some of the effects of this drug.