1998 年 58 巻 3 号 p. 125-135
A continuous microwave sterilizer (MWS) was developed. The MWS is a new sterilization system using microwave dielectric heating. Its temperature characteristics, selection of biological indicators, and sterilizing ability were reported in our previous papers. Here we report the application of the MWS to thermally labile drug solutions whose sterilization was not possible with conventional autoclaving. We selected nine strains of microorganisms with heat resistance close to that of microorganisms found in a bioburden. Each microbial suspension (106 to 107 cfu/ml) was heated for 12 sec with the MWS at 81-128°C. Six strains of vegetative-form cells and fungal spores were sterilized completely at 81-86°C. Bacillus subtilis spores and Clostridium sporogenes spores were sterilized at 117-119°C and 123-125°C, respectively. These results suggest that microorganisms detected in a bioburden can be reliably sterilized with the MWS at 81-125°C. The deterioration in quality of thermally labile drug preparations (ascorbic acid solution and pyridoxamine phosphate solution) following sterilization with the MWS or an autoclave was evaluated. When compared with the same Fo value, sterilization with an autoclave resulted in quality deterioration of both preparations, but sterilization with the MWS did not. These results suggest that the MWS allows reliable sterilization of thermally labile drug preparations without quality deterioration. When decompositions of the active ingredient following sterilization were compared, no differences were observed in decompositions induced by the two methods of sterilization, suggesting that the effects of microwave dielectric heating on chemical bonds are similar to the effects of conventional moist heat sterilization.