Effect of medication on biomechanical properties of rabbit bones: Heparin induced osteoporosis

Abstract

The aim of this controlled study is to investigate the effect of heparin on osteoporosis initiation and of calcitonin and tamoxifen on the progress 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 animals in group B were injected the same amount of heparin as those of group 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 intestine via cannula, one side connected to the injector. The animals in group D were the control. The experiment lasted 8 weeks. The animals in all experimental groups showed the same growth pattern as that of the control group. Whole-bone femur, humerus and tibia specimens were subjected 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 using the strength of materials formulae. The data obtained from the bending and the compression experiments were treated separately. The stiffness of the bones of the medicated groups were compared with those of the control groups. Our data indicated that the tamoxifen treated humera, femora and tibiae attained the largest bending stiffness in all cases investigated. However, this was not the case for compression. None of the drug administered groups attained the stiffness of the control group except for the case of tamoxifen treated femora which attained stiffness close to that of the controls. The results show that heparin altered the mechanical properties of bones indicating osteoporosis, tamoxifen was effective in reducing the effect of heparin while calcitonin yielded no conclusive result.

Mapping the Multi‐Directional Mechanical Properties of Bone in the Proximal Tibia

“…For example, bone apparent density, trabecular volume, modulus, strength, and strain energy are all affected by medication. [16] Axial (Z) apparent modulus of the proximal tibia has been recorded by numerous authors with values ranging from 2.5-3780 MPa which agrees well with our data. [5,6,12,[17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] It is noted that a number of studies report apparent modulus to be significantly less or greater than our study, which may be due to differences in experimental method, small samples sizes of predominantly young males or inclusion of cortical bone regions within cubes.…”

“…For example, bone apparent density, trabecular volume, modulus, strength, and strain energy are all affected by medication. [ 16 ]…”

Effect of a Direct Thrombin Inhibitor Compared with Dalteparin and Unfractionated Heparin on Human Osteoblasts

“…This loss in osteoblasts is to be held responsible for the development of heparin-induced osteopenia [10, 13, 14]. …”

“…One of the most sensible markers for heparin-induced osteopenia is a loss in osteoblast number [13-15]. Therefore the aim of this study was to describe the effect of melagatran on human osteoblasts in vitro in comparison to conventional heparins, namely UFH and the LMWH dalteparin.…”

Effects of heparin and low-molecular-weight heparins on bone mechanical properties in rats

“…So far, only a few studies on experimental animals concerning the effect of different heparins on bone mechanical properties were performed (5,8,19,29) and were inconclusive; either both standard heparin and a low-molecular-weight heparin were reported to not affect bone mechanical properties (5,8) or a low-molecular-weight heparin was less damaging (23).…”