Imbalance in the activities of osteoclasts (cells responsible for bone loss) and osteoblasts (cells responsible for bone formation) may lead to fractures, osteopenia, and osteoporosis in postmenopausal women. During postmenopause, decreased estrogen levels and decreased nitric oxide production occur; estrogen replacement therapy has been shown to restore serum nitric oxide levels to normal. Reversing nitric oxide deficiency by using nitroglycerin may prevent further bone loss. The Nitroglycerin as an Option: Value in Early Bone Loss (NOVEL) study will test the safety and efficacy of nitroglycerin ointment for the treatment of osteopenia in postmenopausal women.