Many drugs can affect bone metabolism. As an example, heparin, warfarin, cyclosporine, glucocorticoids, medroxyprogesterone acetate, cancer drugs and thyroid hormone can cause bone loss, while thiazide diuretics can minimize bone loss [1,2]. This topic will review the skeletal effects of some of these drugs. The effects of glucocorticoids, aromatase inhibitors, and thyroid hormone are discussed separately. (See "Pathogenesis, clinical features, and evaluation of glucocorticoid-induced osteoporosis" and "Evaluation and management of aromatase inhibitor-induced bone loss" and "Bone disease with hyperthyroidism and thyroid hormone therapy".)
DRUGS THAT MAY HAVE ADVERSE EFFECTS
Heparin — Heparin causes bone loss by decreasing bone formation. The few studies of the mechanism of bone loss have revealed decreased bone formation [1,3], increasing bone resorption , or both .
Since heparin is usually given for brief periods of time, its adverse effect on the skeleton should be trivial. However, it may be given for a prolonged period during pregnancy, since warfarin is relatively contraindicated in the first trimester due to its teratogenic effects . As a result, most of the information concerning the adverse effects of heparin on bone comes from studies of pregnant women requiring anticoagulation.
Chronic heparin therapy reduces bone mineral density [6-8]. In one study, for example, in 14 heparin-treated pregnant women and 14 untreated pregnant women, mean hip density fell significantly by about 5 percent in the women receiving heparin; there was no change in the control group . Hip density decreased by more than 10 percent in 5 of the 14 women taking heparin (36 percent) versus none of the control group. Similar results were reported in another controlled study, which examined the effect of heparin on forearm density .
There are many case reports and series of pregnant women with osteoporotic fractures during and after prolonged heparin therapy [1,9]. One of the largest studies followed 184 pregnant women who were given heparin: four (2.2 percent) had osteoporotic vertebral fractures . Although the incidence of fractures was low, they occurred in young women in whom osteoporotic fractures are extremely rare. (See "Use of anticoagulants during pregnancy and postpartum".)