Bone Abstracts

In postmenopausal women, estrogen deficiency not only interferes with the metabolism of the bone tissue, but also adversely affects the cardiovascular system and can cause hypertension. Doxazosin is often used in the treatment of resistant hypertension, especially in patients with renal failure and hyperlipidemia. Vasodilator effect of doxazosin is associated with selective blocking of α1 receptors in the smooth muscle cells of resistance arterioles. The results of epidemiological studies on the effects of α1-blockers on the skeletal system are contradictory and no studies on the effect of doxazosin on the development of experimental estrogen deficiency-induced osteoporosis have been reported. The aim of this study was to investigate the effect of doxazosin on bone remodeling and mechanical properties of the femur in ovariectomized rats.

The experiments were performed on 3-month-old female Wistar rats, divided into four groups (n=9–10): sham-operated control rats, ovariectomized (OVX) control rats, OVX rats treated with doxazosin 0.5 or 5 mg/kg p.o. daily for 4 weeks. The bilateral ovariectomy was performed 7 days before the start of doxazosin administration. Femoral bone mass, mineralization, histomorphometric parameters (periosteal and endosteal transverse growth, cortical bone and marrow cavity area in the diaphysis, and trabecular width in the epiphysis and metaphysis) and mechanical properties of the diaphysis and neck were investigated.

Estrogen deficiency induced osteoporosis with intensification of bone resorption and formation. Doxazosin dose-dependently counteracted the development of osteoporosis, increasing bone formation and/or inhibiting bone resorption in cancellous and compact bone. Moreover, doxazosin improved mechanical properties of compact bone (the femoral diaphysis).

In conclusion, the results of this experimental study using an animal model of osteoporosis, suggest that doxazosin used in the treatment of hypertension may decrease the risk of osteoporosis in postmenopausal women.