Aqueous humour pralidoxime mesylate (P2S) concentrations and intraocular tension following intramuscular P2S

Small transient increases in rabbit intraocular tension were measured following intramuscular pralidoxime mesylate (P2S) at doses of 10, 40 or 100 mg/kg. Peak increases in tension showed some dose dependency, and although not statistically correlated with plasma or aqueous humour P2S concentrations the changes in tension followed the general time-concentration profile for P2S in these fluids. P2S was not detected in aqueous humour following 10 mg/kg, but at 40 and 100 mg/kg dose dependent concentrations were detected in aqueous humour. From experiments involving multiple injections of P2S there was no evidence for a cumulative effect of P2S on the eye. The results indicate that P2S can enter aqueous humour following its parenteral administration and is associated with changes in intraocular fluid dynamics. Whilst they also suggest that some ophthalmic side-effects of oxime therapy may be a consequence of a direct action of the oxime on the eye, they do not exclude contributions from actions at other sites.