The results with all concentrations

The results with all concentrations of citric and tartaric acidswere somewhat similar. Figure 1 shows the decomposition ofaspirin at 45, 26, and 4" in the polyethylene glycol suppositorybase when no additive was used. As in numerous other studies (3),the decomposition of aspirin was highly temperature dependent.The decomposition was approximately 267; in 28 days at 45",about 187; in 80 days at 26". and approximately 377, in 100 daysat 4". Refrigeration of aspirin suppositories utilizing a polyethyleneglycol base is a necessity.Figure 2 shows the decomposition of aspirin in the polyethyleneglycol base in the presence of I citric acid. The decompositionwas inhibited particularly at 26 and 4". At 45". the decompositionreached about 23% at 28 days; at 26". it was around 1 1% after102days; and at 4', it reached just over 2%in 110days.An increase in citric acid concentration to 5 % resulted in afurther decrease in the decomposition rate at 26 and 4", but n ochange was noted at 45". The decomposition at 26' reached about8% in 100days, while at 4"it was only about 1 %.There was little or no improvement in the stability of aspirinwith 10% citric acid compared to the 5 % concentration. Citricacid at the 10% level inhibited the decomposition of aspirin evenin the presence of 5 % added water. The rate of decomposition wasgreater than that shown without water but less than that of the control.