SDX-308 and SDX-101 do not affect preosteoclast development. Purified cells from CFU-GM colonies were cultured with 10 ng/mL M-CSF and 50 ng/mL RANKL for 21 days. Control (DMSO 0.1%), SDX-101 (75 μM), or SDX-308 (7.5 μM) was added to the culture twice a week. Drugs were added (A) for either for the first week only, the first 2 weeks, or all 3 weeks or (B) for either the last week only, the last 2 weeks, or all 3 weeks. Cells were then fixed and stained with 23c6 antibody to detect the multinucleated mature OCLs. Data shown are the mean ± SD of multinucleated cells (MNCs) per well of at least 8 wells. Asterisks indicate significant difference from control (P < .05). All experiments were performed independently 3 times.