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April 1985

Pilocarpine and Acetylcholine Synthesis

Author Affiliations

Kuopio, Finland
Turku, Finland

Arch Ophthalmol. 1985;103(4):477. doi:10.1001/archopht.1985.01050040019006

To the Editor.  —In their article in the October 1984 Archives, Mindel and Kharlamb1 elegantly demonstrated the activation of acetylcholine synthesis by pilocarpine hydrochloride in vitro in the ocular tissues of humans and rabbits. The biosynthesis was activated only at millimolar (1mM to 60mM) pilocarpine concentrations. Neither at in vitro concentrations lower than 1mM nor in the in vivo experiment was acetylcholine synthesis activated.The discussion concerning the clinical significance of the finding was based on the claim that the administration of clinical doses of pilocarpine results in millimolar drug concentrations (27mM) in the rabbit eye. The lack of activation of acetylcholine synthesis by the drug in rabbit eyes was explained by the extensive ocular metabolism of the drug. As the metabolism of pilocarpine in the human eye has not been studied, the question of active drug concentration in the human eyes remained open. Consequently, Mindel and Kharlamb1