Volume 26 (1978) Issue 10 Pages 2983-2989
Volatile medicinals, naphthalene, d-camphor, and p-cresol became amorphous during grinding with microcrystalline cellulose. The medicinal of interest was retained in the ground mixture even when the mixture was heated at moderately high temperature in vacuo. The close relationship was noticed between the retentivity and the state of the medicinals (amorphous or not) in the ground mixture. The amount of the medicinal remaining in the ground mixture was influenced by the medicinal content, the grinding time, and the amount of water adsorbed. The medicinals were very rapidly released from the ground mixture into water. The mechanism for these results was discussed, based on the structure of the groud mixture proposed in the previous paper as follows : the molecules of the volatile medicinals are enclosed by the cellulose molecules that were bound by hydrogen bonds between hydroxyl radicals. The system was regarded as an "entropy frozen solution" of the medicinal in cellulose molecules. By adding water to the ground mixture, the hydrogen bonds are weakened and the medicinal molecule obtains the ability of molecular movement.