Subsensitivity to cholinoceptor stimulation of the human iris sphincter in situ following acute and chronic administration of cholinomimetic miotic drugs.
1 Maximal pupillary miosis was obtained with single topical applications of 4 cholinomimetic drugs in therapeutic concentrations to normal human subjects. 2 When the pupil had recovered from the miosis, there remained a reduced light reflex response of 22.7% at 24 h after aceclidine, 18.0% at 31 h after pilocarpine, 10.3% at 48 h after physostigmine and 4.9% at 7 h after arecoline. 3 This reduced sensitivity to light was accompanied by an overshoot of the resting pupil diameter and, after aceclidine miosis, a reduced response to a second application of miotic. 4 Similar findings were observed in glaucoma patients following withdrawal of chronic pilocarpine therapy. 5 It is suggested that the slowly reversible after-effects of acute and chronic administration of cholinomimetic miotics can be explained by desensitization of iris sphincter cholinoceptors.
D000328:Adult; D001115:Arecoline / Q000494:pharmacology; D005901:Glaucoma / Q000188:drug therapy; D006801:Humans; D007498:Iris / Q000187:drug effects*; D008027:Light; D008916:Miotics / Q000494:pharmacology*; D010277:Parasympathomimetics / Q000494:pharmacology*; D010830:Physostigmine / Q000494:pharmacology; D010862:Pilocarpine / Q000494:pharmacology; D011680:Pupil / Q000187:drug effects; D011812:Quinuclidines / Q000494:pharmacology; D011950:Receptors, Cholinergic / Q000187:drug effects*; D013997:Time Factors
D008916:Miotics; D010277:Parasympathomimetics; D011812:Quinuclidines; D011950:Receptors, Cholinergic; D010862:Pilocarpine; D001115:Arecoline; D010830:Physostigmine