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ABSTRACT-The bisphosphonates, which are carbon-substituted pyrophosphates, have been studied exten sively both in vivo and in vitro to elucidate their effects on bone tissues and cells. However, because these agents were shown to have a potent inhibitory effect on bone resorption, the majority of studies have focused on only this aspect of bone metabolism. There appears to be less information regarding the direct effect of bisphosphonates on bone formation, so thus we undertook experiments to investigate the effects of bisphosphonates, especially alendronate, on the mineralization and matrix protein synthesis of human osteoblastic cells in vitro. The data show that the bisphosphonates, alendronate, etidronate and pamidronate, suppressed 1,25-dihydroxycholecalciferol (1,25(OH)2D3)-stimulated mineralization of human osteoblastic cells at high concentrations, while relatively lower concentrations of alendronate and etidronate potentiated mineralization of the cells in the presence of 1,25(OH)2D3. The potentiation of mineralization with alendronate was accompanied by increased synthesis of bone matrix proteins, osteocalcin and col lagen, and the mRNA of pro a(I) collagen. These findings show that in addition to their well-known effects on bone resorption, bisphosphonates have significant and direct effects on osteogenesis in osteoblasts in vitro. The actual mechanism remains to be further investigated.

A single oral dose of 20 mg febuxostat was administered to subjects with normal, mild or moderate impairment in renal function. There was less than a 2-fold difference in AUC of plasma unchanged febuxostat among the renal function groups, and changes in plasma urate levels from pre-dose levels were not significant. A total of five adverse events were reported with all mild in severity. The results indicate that renal impairment will have little clinical impact on the pharmacokinetics (PK), pharmacodynamics (PD) and safety of the study drug.

Joint 11 th International and 9 th European Symposium on Purines and Pyrimidines in Man]. -(KOMORIYA*, K.; HOSHIDE, S.; TAKEDA, K.; KOBAYASHI, H.; KUBO, J.; TSUCHIMOTO, M.; NAKACHI, T.; YAMANAKA, H.; KAMATANI, N.; Nucleosides, Nucleotides