Effect of certain additives on stability of streptomycin sulphate

The effect of certain additives on the stability of streptomycin sulphate at 37 and 60 degrees C, for one month was studied. In pure distilled water, streptomycin sulphate was stable for 21 d at 37 degrees C, while at 60 degrees C a significant loss occurred after only three d. The effect of McIlvain buffer at different pH values showed maximum stability at pH values of 6.5 and 7. The stability was altered when Sörensen buffer at pH = 6.5 was used. On the other hand, the effect of other commonly used additives demonstrated that at 37 degrees C Aerosil 200, kaolin and pectin did not cause any significant loss, while bentonite caused significant decrease in the activity after 15 d. In contrast, activated charcoal and veegum reduced the activity to 54.5% and 57.5%, after just 1 d and to zero after 4 d, respectively. At 60 degrees C, the rate of decomposition of streptomycin sulphate was highly accelerated.