Osteoclast inhibitory effects of vitamin K2 alone or in combination with etidronate or risedronate in patients with rheumatoid arthritis: 2-year results.

To investigate the effects of vitamin K2 (Vit K2) alone or in combination with etidronate and risedronate on bone loss, osteoclast induction, and inflammation in patients with rheumatoid arthritis (RA).Subjects comprised 79 patients with RA who were receiving prednisolone, divided into 3 groups: Group K, Vit K2 alone; Group KE, Vit K2 plus etidronate; and Group KR, Vit K2 plus risedronate. During a 24-month treatment and followup period, levels of N-terminal telopeptide of type I collagen (NTx) and bone alkaline phosphatase were measured. Bone mineral density (BMD) of the 3 groups was measured using dual-energy x-ray absorptiometry. Damage score to fingers on radiographic findings were measured according to the Larsen method. Serum levels of receptor activator of nuclear factor-kappaB ligand (RANKL) and osteoprotegerin (OPG) were measured.Falls in rate of change of BMD decreased after 18 months in groups KR and KE. Larsen damage scores indicated a significant difference between Group KE and other groups. Significant decreases in serum NTx were observed in groups KE and KR at all timepoints, but not in Group K. Levels of RANKL decreased significantly in all 3 groups.Vit K2 alone or in combination with bisphosphonates for treatment of osteoporosis in patients with RA may inhibit osteoclast induction via decreases in levels of RANKL.