PROPOFOL AND THIOPENTAL IN A 1 1-VOLUME MIXTURE IS CHEMICALLY STABLE/

Propofol and thiopental have been used clinically in combination for i nduction of anesthesia. Studies suggest that this mixture has synergis tic activity, recovery characteristics similar to propofol alone, and bactericidal effects on multiple organisms. Ii may therefore be both c linically useful and cost-effective. In this study, we examined the ch emical stability of this mixture, We used high-performance liquid chro matography to quantify the concentration of both propofol and thiopent al in a given sample, This technique allows the detection of loss in t otal drug mass and of the appearance of breakdown products resulting f rom drug interaction. Ten samples of a 1:1 mixture by volume were prep ared and assayed at Time 0 and Days 1, 3, and 7. Half the samples were incubated at 23 degrees C and the rest were stored at 4 degrees C. Ot her mixtures were assayed before and after filtration at Time 0 and Da ys 1 and 7 after storage at 23 degrees C. The assay was able to measur e accurately the quantity of drug present in the samples. There was no significant decrease in the quantities of either propofol or thiopent al in the mixture over the 7-day period. We conclude that the 1:1 volu me mixture of propofol and thiopental is chemically stable for 1 wk at room temperature. Implications: A mixture of propofol and thiopental has been used to induce anesthesia. We investigated the chemical stabi lity of this mixture using highperformance liquid chromatography and f ound it to be stable for at least 24 h.