ABSTRACT
Formestane is an inhibitor of the aromatase enzyme which is uniquely responsible for the generation of estrone and estradiol from androgenic precursors. Formestane is used in the treatment of breast cancer in postmenopausal women. Formestane causes reduction of the estrogen biosynthesis in all tissues where it occurs. Deficiency of estrogens disrypts remodeling of bone tissue. The effect of formestane on bones in not known. The aim of the present study was to investigate the effects of formestane (20 mg/kg s.c. once a week) administered for 4 weeks on the osseous system in bilaterally ovariectomized and non-ovariectomized rats. The experiments were carried out on 4 groups of 3-month-old female Wistar rats:I--Control (non-ovariectomized rats), II--Ovariectomized rats, III--Non-ovariectomized rats + Formestane, IV--Ovariectomized rats + Formestane. In all the groups examined were body weight gain, bone mass, length and diameter, mineral and calcium contents in the tibia and femur, endosteal and periosteal transverse growth, endosteal and periosteal osteoid width transverse cross-section area of the cortical diaphysis and that of the marrow cavity in the tibia, epiphyseal cartilage width, trabeculae width in the epiphysis and metaphysis of the femur. Mechanical properties of the femur were also studied. Bilateral ovariectomy induced osteopenic skeletal changes in female rats. Formestane did not significantly change bone remodeling in non-ovariectomized rats (group III). Formestane administered to the bilaterally ovariectomized rats (group IV) slightly reduced the changes by ovariectomy in the osseus system.
