1983 年 103 巻 2 号 p. 213-224
The size and its distribution of the particles reduced by wet grinding (pulverization by intervention) of five kinds of solid drugs using mortar and pestle or a ball mill were determined. The results obtained were compared with those by dry grinding and a number of conclusions were drawn as in the following way : 1. d-Camphor which belongs to a plastic crystal was easily pulverized in the presence of ether ; however, once the solvent was evaporated, masses were formed by continued impaction due to plasticity and the particle size became progressively enlarged. Accordingly, it is certain that the liquid ether among particles prevent plastic conglomeration of d-camphor. 2. Size-reducibility of d-camphor in the presence of potato starch by dry trituration with mortar and pestle was examined. As was expected from the above, the size of d-camphor could effectively reduced because the starch particles acted as a grinding aid by gathering around those of d-camphor. 3. It was demonstrated by low temperature differential scanning calorimetry that the heat of fusion of d-camphor was abnormally small as compared with the heat of transition at -29°C ; accordingly, its fusion entropy was estimated to be 2.9 cal deg-1 mol-1, and was much smaller than those of the ordinary organic crystals. 4. Next to d-camphor, wet grinding of l-menthol with ether or ethanol was found effective. In this case, however, size reduction was rather attributable to the fine crystals separated from the very thick solution of l-menthol in these solvents. Since on continued ball-milling after evaporation of the solvent, it is certain that l-menthol crystals have some plasticity and that the intervented solvent will also take part in reduction of the particle size by preventing conglomeration. 5. It is evident the wet grinding is an unnecessary procedure for the size reduction of brittle crystals such as the ones of ethyl p-aminobenzoate, salicylic acid, and aspirin, since the particles of them were equally reduced either by wet or by dry trituration.