Troglitazone has no effect on red cell mass or other erythropoietic parameters

Objective: Troglitazone is a new anti-diabetic agent for the treatment of t ype 2 diabetes. In placebo-controlled trials troglitazone improves glycaemi c control, reduces hyperinsulinaemia and has beneficial effects on blood li pids. However, minor, reversible reductions in erythrocyte count, haemoglob in and haematocrit with no associated clinical symptoms have been observed in some troglitazone-treated patients. The primary objective of the present study was to determine if these changes could be explained by a decrease i n red cell mass or change in plasma volume. Methods: Twenty-four healthy males were randomized in a double-blind manner to troglitazone (200 or 600 mg per day) or placebo for 6 weeks. Blood samp les for the measurement of red cell mass and plasma volume were obtained in the 2 weeks prior to treatment and after 6 weeks of treatment. Reticulocyt e and erythrocyte counts, haemoglobin and haematocrit were also measured. Results: At the end of the treatment period there were no statistically sig nificant changes in red cell mass. Similarly there were no changes in retic ulocyte count, erythropoietin or soluble transferrin receptors. These data indicate that troglitazone does not affect erythropoiesis. In addition, tro glitazone was not associated with increased red blood cell destruction or h aemolysis. There was a trend towards increased plasma volume in the troglit azone groups: increases of 2.5 mi . kg(-1) (5.7% increase) in the troglitaz one 200 mg group and 3.4 ml . kg(-1) (7.8% increase) in the troglitazone 60 0 mg group were observed compared with placebo. Conclusion: These data suggest that dilutional effects related to a modest increase in plasma volume may explain the haematological changes seen in ot her clinical trials with high doses of troglitazone, although this study ha s shown that the changes in plasma volume are not statistically significant .