title: IINFLUENCE OF THE IMMUNOSUPPRESSANT TACROLIMUS (FK-506) ON THE FLEXURAL STRENGTH OF FEMUR: A STUDY IN RATS.
abstract: OBJECTIVE
  To evaluate the resistance to femoral fractures among rats treated with the immunosuppressant tacrolimus FK-506 and compare these to untreated rats and rats treated with placebo.
  
  
  METHODS
  Ninety male Wistar rats were used. The animals were nine weeks old and weighed between 220 g and 280 g. The immunosuppressive agent tacrolimus was used in this study at a dose of 2 mg/kg/day, administered orally. The suspension was administered using an insulin syringe, and the maintenance therapeutic dose was sufficient to maintain the immunosuppressive activity. The animals were randomly divided into three groups (n = 30): group 1, no substance administered; group 2, administration of the immunosuppressant tacrolimus FK-506; and group 3, administration of the vehicle alone. Treatment with FK-506 was administered for 28 days. Total leukocyte counts and differential counts (lymphocytes, monocytes, eosinophils and neutrophils) were evaluated in order to monitor the immunosuppressive effect. Bone densitometry analysis by means of dual-energy x-ray absorptiometry (DXA) was also performed before and after administration of the drug. To evaluate the resistance to flexion, a support device was developed so that mechanical tests using an EMIC universal testing machine could be carried out.
  
  
  RESULTS
  The results from the flexion resistance tests showed statistical differences between groups 1 and 2 (p = 0.001) and between groups 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 the immunosuppressive agent had lower mechanical strength than did those of normal rats and those that received placebo.
authors.affiliation: Specialist title in Orthodontics from the Federal University of Alfenas (Unifal); MSc in Orthodontics from the Federal University of Rio de Janeiro (UFRJ); PhD student of Orthodontics at the Federal University of Rio de Janeiro (UFRJ); Auxiliary Professor in the field of Orthodontics at the State University of Southwestern Bahia (UESB).
authors.forename: Matheus Melo
authors.initials: MM
authors.lastname: Pithon
authors.affiliation: Physician, graduated from the Bahia School of Medicine and Public Health (EBMSP).
authors.forename: Ana Carolina Dias Viana
authors.initials: AC
authors.lastname: de Andrade
authors.affiliation: Undergraduate student in the medical course at the State University of Southwestern Bahia.
authors.forename: Vinícius
authors.initials: V
authors.lastname: de Brito Rodrigues
authors.affiliation: Specialist title in Orthodontics from the Federal University of Alfenas (Unifal); MSc in Orthodontics from the Federal University of Rio de Janeiro (UFRJ); PhD student of Orthodontics at the Federal University of Rio de Janeiro (UFRJ).
authors.forename: Rogério Lacerda
authors.initials: RL
authors.lastname: Dos Santos
keywords: Densitometry; Femoral fractures; Tacrolimus