Bone remodeling after administration of proton pump (H+/K+-ATPase) inhibitors and alendronate in ovariectomized rats.

During osteoporosis therapy with alendronate, esophagitis and stomach ulceration may occur, requiring the concurrent use of drugs which decrease gastric juice production. The aim of the present study was to investigate the effect of concurrent administration of proton pump (H+/K+ATP-ase) inhibitors: omeprazole or pantoprazole and alendronate on bone remodeling in ovariectomized rats. The experiments were carried out on 3-month-old Wistar rats, divided into following groups (n = 8-10): NOVX - non-ovariectomized control rats; OVX - ovariectomized control rats; OVX + alendronate; OVX + omeprazole; OVX + omeprazole + alendronate; OVX + pantoprazole; OVX + pantoprazole + alendronate. The drugs were administered for 28 days: alendronate (3 mg/kg p.o.), omeprazole or pantoprazole (3 mg/kg i.p.). Bone remodeling was estimated based on histomorphometric evaluation of the tibia (endosteal and periosteal transverse growth and the osteoid width, transverse cross-section surface of the diaphysis and of the marrow cavity) and the femur (width of trabeculae in the distal epiphysis and metaphysis). Bone mass/100 g body mass and mass of bone mineral/100 mg bone mass in the tibia and femur were also determined. Pantoprazole stronger than omeprazole intensified bone remodeling disorders caused by estrogen deficiency in ovariectomized rats. Bone remodeling disorders were the result of intensification of bone resorption with concurrent inhibition of bone formation and mineralization. Pantoprazole, and to lesser extent omeprazole, weakened the preventive effect of alendronate on bone remodeling in ovariectomized rats.