There is concern about the possibility of degradation of the active substance as a result of pH changes when making suspensions of several drugs together by the simple suspension method.However,this has been investigated by few researchers.In the present study,we focused our attention on aspirin since it is known to be hydrolyzed at high temperatures or with elevation in pH.In this study,a Bufferin® 81 mg Tablet was suspended alone or together with alkaline drugs by the simple suspension method,and its stability evaluated.
When in the suspension alone,the Bufferin® 81 mg Tablet was stable for 5 hours and the amount of salicylic acid (hydrolyte of aspirin) produced was negligible.On the other hand,when it was suspended together with alkaline agents (magnesium oxide tablet/powder,or lithium carbonate tablet),the residual content of aspirin decreased to 77-84% in ten minutes.The pH of the suspensions containing both the Bufferin® 81 mg Tablet and alkaline agents ranged from about 9 to 10 showing that alkalinity had been enhanced as compared with the suspension of Bufferin alone whose pH was 4.
It has been reported that in low-dose aspirin therapy,platelet aggregation inhibition is unstable if the daily aspirin dosage is reduced to less than 75 mg.However for Bufferin® 81 mg Tablet,the results of the present study suggested that the beneficial effect of low-dose aspirin therapy might not be fully achieved it were suspended together with alkaline agents by the simple suspension method.
