title: A selective inhibitor of the osteoclastic V-H(+)-ATPase prevents bone loss in both thyroparathyroidectomized and ovariectomized rats.
abstract: A potent and selective inhibitor of the osteoclastic V-H(+)-ATPase, (2Z,4E)-5-(5,6-dichloro-2-indolyl)-2-methoxy-N-(1,2,2,6, 6-pentamethylpiperidin-4-yl)-2,4-pentadienamide (SB 242784), was evaluated in two animal models of bone resorption. SB 242784 completely prevented retinoid-induced hypercalcemia in thyroparathyroidectomized (TPTX) rats when administered orally at 10 mg/kg. SB 242784 was highly efficacious in the prevention of ovariectomy-induced bone loss in the rat when administered orally for 6 months at 10 mg/kg/d and was partially effective at 5 mg/kg/d. Its activity was demonstrated by measurement of bone mineral density (BMD), biochemical markers of bone resorption, and histomorphometry. SB 242784 was at least as effective in preventing bone loss as an optimal dose of estrogen. There were no adverse effects of compound administration and no effects on kidney function or urinary acidity. Selectivity of the inhibitor was further studied using an in situ cytochemical assay for bafilomycin-sensitive V-H(+)-ATPase using sections of osteoclastoma and numerous other tissues. SB 242784 inhibited the osteoclast enzyme at 1,000-fold lower concentrations than enzymes in any of the other tissues evaluated. SB 242784 demonstrates the utility of selective inhibition of the osteoclast V-H(+)-ATPase as a novel approach to the prevention of bone loss in humans.
authors.affiliation: SmithKline Beecham S.p.A, Milano, Italy. SmithKline Beecham Pharmaceuticals, Bone and Cartilage Biology, King of Prussia, Pennsylvania, USA.
authors.forename: L
authors.initials: L
authors.lastname: Visentin
authors.forename: R A
authors.initials: RA
authors.lastname: Dodds
authors.forename: M
authors.initials: M
authors.lastname: Valente
authors.forename: P
authors.initials: P
authors.lastname: Misiano
authors.forename: J N
authors.initials: JN
authors.lastname: Bradbeer
authors.forename: S
authors.initials: S
authors.lastname: Oneta
authors.forename: X
authors.initials: X
authors.lastname: Liang
authors.forename: M
authors.initials: M
authors.lastname: Gowen
authors.forename: C
authors.initials: C
authors.lastname: Farina
mesh_terms: D000143:Acids / Q000032:analysis; D000284:Administration, Oral; D000818:Animals; D001565:Benzoates / Q000494:pharmacology; D015519:Bone Density; D001862:Bone Resorption / Q000188:drug therapy*; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000627:therapeutic use; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D005269:Femur / Q000473:pathology; D006934:Hypercalcemia / Q000188:drug therapy; D007211:Indoles / Q000627:therapeutic use*; D008161:Lumbosacral Region; D010010:Osteoclasts / Q000187:drug effects / Q000201:enzymology*; D010024:Osteoporosis / Q000188:drug therapy*; D010052:Ovariectomy; D016105:Parathyroidectomy; D010880:Piperidines / Q000627:therapeutic use*; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012176:Retinoids / Q000494:pharmacology; D013131:Spine / Q000473:pathology; D013965:Thyroidectomy; D014556:Urine / Q000737:chemistry; D025262:Vacuolar Proton-Translocating ATPases; D014617:Vacuoles / Q000187:drug effects / Q000201:enzymology*
chemical_list: D000143:Acids; D001565:Benzoates; D004791:Enzyme Inhibitors; D007211:Indoles; D010880:Piperidines; D012176:Retinoids; C118025:SB 242784; D004958:Estradiol; C034814:ethyl-p-((E)-2-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthyl)-1-propenyl)benzoic acid; D025262:Vacuolar Proton-Translocating ATPases; D006180:Proton-Translocating ATPases