Kinetics of the hydrolysis of pilocarpine in aqueous solution.

The kinetics of the hydrolysis of pilocarpine in aqueous solution were investigated utilizing pH-stat titrimetry and polarimetry. A cyclic mechanism was proposed for the hydrolysis, which is catalyzed by both hydrogen ion and hydroxide ion. The appropriate rate constants, equilibrium constants, and the energy of activation for the hydroxide-ion catalyzed hydrolysis were calculated. The hydrolysis in high alkaline pH was found to be accompanied by some epimerization. An optimum condition for the preparation of pilocarpine ophthalmic solution was also suggested.

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