Abstract: Objective To study the effects of G48A and alendronate in activation-depression-free-repeat (ADFR) scheme on ovariectomized rats．Methods Seventy-five three month old female Sprague-Dawley rats were randomly divided into 7 groups: sham-operated(S) group , ovariectomized (OVX)group, alendronate group(ALEN), G48A and alendronate group(non-ADFR group), and the other three groups were treated by the ADFR scheme with G48A and alendronate given intermittently by different time schedule :5-5-5d(group G48A1)，10-10-5d(group G48A2), 14-4-7d(group G48A3). All rats were sacrificed 13 weeks after the operation．The BMD of femora and lumbar vertebra and the biomechanical parameters were measured．Results Body weight increased and BMD decreased in OVX compared those with S group.The lumb and vertebral BMD ,the vertebral elastic load ,the femoral flexural modulus and flexural rigidy coefficient in groups G48A1,2,3 and non ADFR group were significantly increased compared with those in group OVX．The BMDs of ADFR groups and non-ADFR group did not have significant difference compared with S group. Conclusion The bone loss decreased and the biomechanics improved in ovariectomized rats with the treatment of G48A and alendronate given by ADFR scheme.

Key words: osteogenic growth peptide, osteoporosis, ADFR, bone minieral density, bone biomechanics