Inhibition of pilocarpine-induced aqueous humor flare, hypotony, and miosis by topical administration of anti-inflammatory and anesthetic drugs to dogs.
OBJECTIVE
To investigate the mechanism by which pilocarpine causes increased aqueous humor (AH) flare, hypotony, and miosis in dogs.


METHODS
6 dogs with normal eyes.


METHODS
Both eyes of each dog were treated topically with a 2% solution of pilocarpine, and 1 eye of each dog was additionally treated with commercially available ophthamic solutions. Breakdown of the blood-aqueous barrier (BAB) was quantitated in each eye, using laser flaremetry to measure AH flare. Intraocular pressure and pupil size were also measured.


RESULTS
Pilocarpine caused increased flare from BAB breakdown that was inhibited by the drugs tested. Inhibition (most to least) of BAB breakdown was flurbiprofen more than diclofenac, proparacaine, or suprofen, which were more than 0.125 or 1.0% prednisolone. Inhibition appeared dose-dependent and caused consensual inhibition in the contralateral eye. Intraocular pressure was decreased only in proparacaine-treated eyes and increased in eyes treated with nonsteroidal anti-inflammatory drugs (NSAID). Flurbiprofen and proparacaine were the most effective at blocking miosis.


CONCLUSIONS
Pilocarpine produced a predictable, reproducible BAB breakdown in dogs. Miosis and increased AH flare were inhibited equally by proparacaine or NSAID, suggesting that these signs were caused by neuropeptide release into the AH from antidromic stimulation, which subsequently triggers prostaglandin production. Hypotony was inhibited only by anti-inflammatory drugs.


CONCLUSIONS
Proparacaine in combination with pilocarpine would be the best choice for treating dogs with acute glaucoma. Topical administration of NSAID should not be used to treat dogs with acute glaucoma, because they increase intraocular pressure and negate the effects of pilocarpine.
Krohne
S G
SG
Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Purdue University, West Lafayette, IN 47907-1240, USA.
Gionfriddo
J
J
Morrison
E A
EA
D000287:Administration, Topical; D000779:Anesthetics, Local / Q000494:pharmacology*; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D001082:Aqueous Humor / Q000187:drug effects* / Q000502:physiology; D004008:Diclofenac / Q000494:pharmacology; D004285:Dogs; D005480:Flurbiprofen / Q000494:pharmacology; D007429:Intraocular Pressure / Q000187:drug effects / Q000502:physiology*; D015877:Miosis; D015814:Ocular Hypotension / Q000139:chemically induced / Q000503:physiopathology*; D010862:Pilocarpine / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000633:toxicity*; D011239:Prednisolone / Q000494:pharmacology; D011430:Propoxycaine / Q000494:pharmacology; D013496:Suprofen / Q000494:pharmacology; D013997:Time Factors
D000779:Anesthetics, Local; D000893:Anti-Inflammatory Agents; D010862:Pilocarpine; D004008:Diclofenac; D005480:Flurbiprofen; D013496:Suprofen; D011239:Prednisolone; C005717:proxymetacaine; D011430:Propoxycaine