Rats bone loss assay: immediately after ovariectomy, two ovx groups were given 10 and 50 mg/kg of CGP77675 by oral gavage twice daily on weekdays and once a day at weekends for 6 weeks. IL-1b-Induced Hypercalcemia: CGP77675 was administered subcutaneously twice daily. The last administration (seventh injection) was given in the morning of day 4.

In vitro, CGP77675 inhibited phosphorylation of peptide substrates and autophosphorylation of purified Src (concentration producing half-maximal inhibition [IC50] values 5–20 and 40 nmol/L, respectively). The compound was selective toward other protein kinases: the Src IC50 value was lower than those for Cdc2 (>500-fold), epidermal growth factor (EGF) receptor (7.5-fold), and vascular endothelial growth factor receptor (>50-fold), and for v-Abl (15-fold) and focal adhesion kinase (Fak) (>25-fold). The Src kinase family members Lck and Yes were inhibited with IC50 values 20-fold higher than or equal to Src. The effect of CGP77675 on bone resorption was evaluated in vitro and in vivo. The parathyroid hormone-induced bone resorption in rat fetal long bone cultures was inhibited with an IC50 of 0.8 mmol/L.