内用液剤の微生物汚染と防腐効果

回服用量の多い内用液剤

抄録

Microbial contamination of residual solutions for the oral liquid preparation of drugs after intake was investigated, and in vitro preservative efficacy of those solutions was studied. Four oral liquid preparations were selected for this study, because they had been administered in large volume without dilution. Three principle results were apparent.
First, the residual solutions of Alloid G^® obtained from outpatients were heavily contaminated by gram-negative bacilli and yeast-like fungi. On the other hand, actual microbial contaminations were not found in Maalox^® and two lacturose preparations. Second, the study of in vitro preservative efficacy indicated that two lacturose preparations exhibited sufficient efficacy to inhibit the microbial growth. However, Alloid G^® and Maalox^® presented conditions suitable for the bacterial growth: liquid pH, concentration of preservative agents, water activity and preparation ingredients. This inadequate preservative efficacy suggested a possibility of microbial contamination for these preparations.
Finally, the low temperature maintained in a refrigerator inhibited the growth of contaminants on the challenging test for Alloid G^® and Maalox^®.
Consequently, the most important factor regarding storage conditions is that Alloid G^® and maalox^® should be kept in the refrigerator immediately after oral intake because of their poor preservative efficacy.