Abstract: Using 2277 bioactivity monitoring system,we determined the changes of heat effect of inhibition of Clarithromycin with Pr(NO3)3 or La(NO3)3 on Escherichia coli growth at 37 ℃.According to the thermokinetic model,the relationship between the concentration of antibiotics (c) and growth rate constant (k) and its half inhibitory concentration,Ic50,were analyzed quantitatively. Clarithromycin: k=0.03106－1.273×10－3c　Ic50=8.81 μg•mL－1　(0.5～20 μg•mL－1) Clarithromycin＋Pr3＋: k=0.02967－1.332×10－3c　Ic50=7.38 μg•mL－1　(1～15 μg•mL－1) Clarithromycin＋La3＋: k=0.02741－1.194×10－3c　Ic50=6.34 μg•mL－1 (1～15 μg•mL－1) 　　The results of microcalorimetry experiments not only indicated that antibacterial activity of Clarithromycin was stronger than that of erythromycin,but also the changeable features of thermokinetics of the bacterial cell in biological,biochemical and metabolic process under the action of different drugs.

Key words: Pr^3＋, La^3＋, Clarithromycin, Erythromycin, 　Escherichia coli, Thermochemistry