OBJECTIVE: To evaluate the resistance to femur fractures in rats treated with the immunosuppressant tacrolimus FK-506 and compare them to untreated rats and rats treated with placebo. METHODS: We used 90 male Wistar rats. The animals were 9 weeks old and weighing between 220 g and 280 g. The immunosuppressive agent tacrolimus, 2 mg / kg / day, orally administered was used in this study. The suspension was administered using an insulin syringe, and the maintenance dose was sufficient to maintain the immunosuppressive activity. The animals were randomly divided into 3 groups (n=30): Group 1, no substance administered; Group 2 was administered the immunosuppressant tacrolimus FK-506; and Group 3 was administered only the vehicle. Treatment with FK-506 was performed for 28 days. Total and differential (lymphocytes, monocytes, eosinophils and neutrophils) leukocyte counts were done to monitor the immunosuppressive effect. Bone densitometry analysis by dual-energy x-ray absorptiometry (DXA) was also done before and after administration of the drug. To evaluate the flexural strength, a support device was developed to aid in mechanical tests using an EMIC universal testing machine. RESULTS: The results of the flexural strength tests showed statistical differences between group 1 and 2 (p = 0.001) and 2 and 3 (p = 0.001). No statistical difference was found between groups 1 and 3 (p = 0.995). CONCLUSIONS: The femurs of rats treated with immunosuppressive agent have lower mechanical strength than those of normal rats and those using placebo.
Femoral fractures; Densitometry; tacrolimus
