EFFECT OF MEDICATION ON BIOMECHANICAL PROPERTIES OF RABBIT BONES - HEPARIN-INDUCED OSTEOPOROSIS

The aim of this controlled study is to investigate the effect of hepar in on osteoporosis initiation and of calcitonin and tamoxifen on the p rogress of osteoporosis induced by heparin through biomechanical means and, thus, to assist in clinical usage of these drugs, 32 four-month- old female New Zealand white rabbits were divided into four different experimental groups, The animals in group A were administered heparin (Liquemine) intraperitoneally at the dosage of 1000 IU/kg/day, The ani mals in group B were injected the same amount of heparin as those of g roup A, and in addition, were given calcitonin at the dosage of 100 IU /kg/day, The animals in group C were medicated the same way as group B but 2 mg/kg/day tamoxifen (Nolvadex) was orally added into their inte stine via cannula, one side connected to the injector, The animals in group D were the control, The experiment lasted 8 weeks, The animals i n all experimental groups showed the same growth pattern as that of th e control group, Whole-bone femur, humerus and tibia specimens were su bjected to 3-point bending tests while sections from the proximal ends of the same specimens were subjected to compression tests, The data, recorded as load vs deflection, were converted into stress vs strain u sing the strength of materials formulae, The data obtained from the be nding and the compression experiments were treated separately The stif fness of the bones of the medicated groups were compared with those of the control groups, Our data indicated that the tamoxifen treated hum era, femora and tibiae attained the largest bending stiffness in all c ases investigated, However, this was not the case for compression, Non e of the drug administered groups attained the stiffness of the contro l group except for the case of tamoxifen treated femora which attained stiffness close to that of the controls, The results show that hepari n altered the mechanical properties of bones indicating osteoporosis, tamoxifen was effective in reducing the effect of heparin while calcit onin yielded no conclusive result.