Recently, automatic tablet counting and packing system (ATC) machines have come to be widely used for the one-dose packing of tablets, capsules, and so on. Although we have also used the ATC at Hachioji Pharmaceutical Center Pharmacy, the coloration (i. e. change in color) was frequently observed in several kinds of tablets contained in the tablet cases of the ATC. The coloration is attributed to light, humidity and temperature in the room.
We have previously reported that there is some possibility of participation of dibutylhydroxytoluene (BHT) which is included in the machine oil or the tablet case as the antioxidant. In the present study, we selected 34 kinds of commercial tablets, which empirically have the possibility of coloration as samples, and examined the effects of coexitence with BHT, light, humidity and temperature on the coloration of tablets. The effects were examined under the following conditions: tablets were stored with or without BHT under 74.9% relative humidity (R. H.) at 60°C to examine of the effect of coexistence with BHT; tablets were exposed to excessive light under 74.9% R.H. at 60°C the effect of light; tablets were stored under 0, 49.9, 74.9% R.H. at 60°C for examination of the effect of humidity; and tablets were stored at 30 and 60°C under 74.9% R.H. to determine of the effect of temperature.
As a result, it was observed that the coloration of several kinds of tablets was accelerated by coexistence with BHT, while the coloration of many kinds of tablets was accelerated by exposure to light and high humidity.