Clofibrate-induced Changes in Rat Erythrocytes are Dependent on Duration of Treatment

The long-term actions of clofibric acid derivatives are interesting both to pharmacology and to therapeutics. Previous work from our laboratory showed changes in erythrocyte membrane protein profile after 40 days of clofibrate daily administration. We report in this paper that long-term oral administration (40 to 60 days) of clofibrate, whose active metabolite is α-chlorophenoxyisobutyric acid (clofibric acid), produces a modification in erythrocyte shape (echynocytosis) and an increase in osmotic resistance probably due to an increase of its surface/volume ratio, in more than 70% of the population of circulating erythrocytes in rats. When these changes are observed at different times (20, 40, and 60 days) after the start of treatment, their quantitative pattern is suggestive of an association with the process of erythrocyte production.