Toxic effect of rifampicin on human osteoblast-like cells

We examined the effects of rifampicin on osteoblast-like cells derided from adult human bone in vitro. Cancellous bone was collected from five different individuals during elective orthopaedic operations and Cultured in antibiotic-free media. Total DNA, H-3-thymidine incorporation and alkaline phosphatase (ALP) activity were measured after the cells were cultured for 4 days in media containing concentrations of rifampicin ranging from 0 to 1000 mug/ml. Mean total DNA was decreased at concentrations of 10 mug/ml and above in the Cultures obtained from four Out of five individuals but these decreases were significant in the Cultures from only two individuals. H-3-thymidine incorporation. a more sensitive indicator of change in cell proliferation. and ALP activity were significantly decreased (P < 0.05) in all of the Cultures containing 3 and 7 <mu>g/ml. respectively. In the clinical setting, serum concentrations of rifampicin often exceed 10 mug/ml after systemic administration. The present Study has shown that rifampicin, at these concentrations. can inhibit the proliferation of osteoblast-like cells in vitro. Further studies should be carried out to assess whether rifampicin is detrimental to the bone repair process in vivo. (C) 2001 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.