Abstract
(1) The decrease of procaine in the aqueous parenteral solution containing 0.5% of procaine hydrochloride and 5% of glucose (PGI) was satisfactorily explained by opposing reactions between formation and hydrolysis of procaine-N-glucoside (PNG). (2) The formation of PNG was proved to be an exothermic reaction, so that at epuilibrium state, higher the temperature, the less the amount of PNG formed, i. e. 66.5% of procaine was combined at 20°and 26.0% at 100°. The heat of reaction was found to be 4.77 Kcal. (3) It was found that the activation energies of formation and hydrolysis of PNG were approximately 14.0 and 18.8 Kcal., respectively. There was a tendency that the velocity constant increases with time, which is considered to be caused by the decrease of pH. (4) From the result obtained, it was concluded that storage of PGI in a refrigerator is not recommended and heat sterilization did not affect the amount of PNG at equilibrium.
