Inhibitory effect of copper complex of indomethacin on bacteria studied by microcalorimetry

A microcalorimetric technique based on the bacterial heat output was explored to evaluate the effect of copper-indomethacin complex on Staphylococcus aureus and Escherichia coli. The extent and duration of the inhibitory effect on the metabolism as judged from the rate constant (k) in log phase, half inhibitory ratio (IC50). The rate constant of bacteria in the presence of the drugs decreased with increasing concentrations of the drugs. The copper complex exhibited higher antibacterial activity than the parent drug whose IC50 value was 1.5 and 2.3 times lower than that of indomethacin to S. aureus and E. coli, respectively. It was indicated that when the copper ion is coupled with indomethacin, the drug is more potent as a bacteriostatic.