ABSTRACT
Single doses (50 microliters) of 1% and 2% pilocarpine, instilled by a buffer-tip droptainer resulting in an approximate pH 7.0 solution, and 1, 2, and 4% pilocarpine, instilled by the standard droptainer, resulting a pH 5.0 solution, were evaluated in the glaucomatous Beagle model. Pupil size and intraocular pressure measurements were performed at 0, 1/4, 1/2, 3/4, 1, 2, 4, 6, and 8 hours. Signs of topical irritation (blepharospasm, conjunctival hyperemia and chemosis, and any corneal changes) were also monitored. Both solutions produced similar onset and duration of miosis and ocular hypotension, but the pH 5.0 solutions produced a brief elevation in intraocular pressure during the first hour post-drug instillation. Moderate blepharospasm, conjunctival hyperemia, and chemosis occurred with only the pilocarpine solutions with pH 5.0.
Subject(s)
Glaucoma/drug therapy , Intraocular Pressure/drug effects , Pilocarpine/administration & dosage , Pupil/drug effects , Administration, Topical , Animals , Blepharospasm/chemically induced , Dogs , Dose-Response Relationship, Drug , Glaucoma/genetics , Glaucoma/physiopathology , Hydrogen-Ion Concentration , Hyperemia/chemically induced , Pilocarpine/adverse effects , Pilocarpine/therapeutic useABSTRACT
Topically applied 4% timolol, 4% timolol combined with 2% pilocarpine, 6% timolol, and 6% timolol combined with 2% pilocarpine were evaluated in clinically normal Beagles and Beagles with glaucoma. The drugs were instilled twice daily for 5 days. Changes in intraocular pressure (IOP), pupil size, and heart rate were recorded on days 1, 3, and 5 at 0, 2, 5, and 8 hours, starting at 8:30 AM. In clinically normal dogs, 4 and 6% topically administered timolol did not cause consistent reductions in IOP; however, with addition of 2% pilocarpine, IOP was consistently lower. In the Beagles with glaucoma, 4 and 6% timolol and, to a greater extent, 4 and 6% timolol combined with 2% pilocarpine lowered IOP. The combinations lowered IOP and reduced pupil size consistently. In all test groups, either 4 or 6% topically applied timolol caused approximately 10% decrease in mean heart rate.
Subject(s)
Adrenergic beta-Antagonists/administration & dosage , Dog Diseases/drug therapy , Glaucoma, Open-Angle/veterinary , Miotics/administration & dosage , Pilocarpine/administration & dosage , Timolol/administration & dosage , Administration, Topical , Animals , Dogs , Dose-Response Relationship, Drug , Drug Administration Schedule , Drug Evaluation , Drug Therapy, Combination , Female , Glaucoma, Open-Angle/drug therapy , Heart Rate/drug effects , Intraocular Pressure/drug effects , Male , Ophthalmic Solutions , Pupil/drug effects , Tonometry, Ocular/veterinaryABSTRACT
Topically applied demecarium bromide (0.125 and 0.25%) and echothiophate iodide (0.125 and 0.25%) solutions were evaluated in Beagles with normotensive eyes and Beagles with inherited glaucoma. In single-dose studies, the effects of intraocular pressure (IOP) and pupil size (PS) were measured in eyes before drug treatment and in drug- and nondrug-treated eyes. Both concentrations of the 2 drugs induced long-term miosis and decrease in IOP in normotensive eyes of Beagles and of eyes of Beagles with inherited glaucoma. Demecarium bromide (0.125 and 0.5%) decreased IOP for 49 and 55 hours, respectively. Echothiophate iodide (0.125 and 0.5%) reduced IOP for 25 and 53 hours, respectively. The miosis associated with both concentrations of the 2 drugs generally paralleled the decreases in IOP.
