The concentration ofthe suspension should
be 20 mglml when calculated based on the
amounts of ingredients in the formula in Table
l. The experimental concentration was only
16.67+0.81 mg/ml or 83.35% of rhe theoretical
concentration. This may be due to the quality of
the drug raw material. However, the point we
would like to study was the stability of the
product. Therefore, the percentag., of initiul
concentration remaining were calculated by
comparing the drug concentrations at the
observed times to the initial concentration. The
results of the percentages of initial concentration
remaining are presented in Table 3. The ranee of
94.71% and 100.56% of the mean lnitiat
norfloxacin concentration remained at ambient
temperature. Assuming that drug concentrations
equal to or greater than 90%o of the initial value
indicate stability, the results indicate that the
suspension, stored in amber glass bottles at
ambient temp€rature, was chemically stable for
85 days. It was found that percentages of drug
remaining at 40oC were higher than 100%. This
may be because of the loss of aqueous medium
while storing in the hot air oven. The stability at
40'C could not be concluded because the
humidity could not be controlled at TS%oRIi.
The data, however, showed variability to some
extent since the heterogeneous property of the
suspension may cause an error in taking samples
and day-to-day variation may also cause the
deviations