The effects of topical ocular application of 0.25% demecarium bromide on serum acetylcholinesterase levels in normal dogs.

OBJECTIVE To assess the effects of topical ocular application of 0.25% demecarium bromide on serum acetylcholinesterase (AChE) levels in normal dogs. ANIMALS Nine adult mixed breed dogs weighing between 18 and 27 kg. PROCEDURES Fifty micro L of 0.25% demecarium bromide were applied to one eye of each dog every 8 h for 6 days. Blood was analyzed for AChE levels prior to commencement of eye drops, and at 45 min, 1 h 45 min, 4 h 45 min, 1 day, 3 days, and 7 days following commencement of eye drops using a 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) reaction. RESULTS Acetylcholinesterase levels declined over the first 24 h following commencement of demecarium administration in most dogs. This decline was highly variable and was statistically significant by 24 h. In some individuals AChE levels were suppressed to levels approaching clinical toxicity. By day 3 AChE levels had risen to levels above baseline in most dogs. CONCLUSIONS Topical ocular application of demecarium causes transient suppression of systemic acetylcholinesterase levels in most dogs. Acetylcholinesterase levels generally do not fall to toxic levels, but may do so in certain individuals. Demecarium bromide eye drops generally do not cause AChE toxicity, but dogs receiving such therapy should be monitored for signs of AChE toxicity, and concomitant use of other AChE inhibitors should be avoided.

[1]  K. Courtney,et al.  A new and rapid colorimetric determination of acetylcholinesterase activity. , 1961, Biochemical pharmacology.

[2]  N. C. Klendshoj,et al.  OBSERVATION OF DANGEROUS SIDE-EFFECT OF PHOSPHOLINE IODIDE IN GLAUCOMA THERAPY. , 1963, American journal of ophthalmology.

[3]  C. Mcculloch,et al.  Cardiac arrest occurring in a patient on echothiophate iodide therapy. , 1965, American journal of ophthalmology.

[4]  C. Mcculloch,et al.  The effect of echothiophate iodide on systemic cholinesterase. , 1966, Canadian journal of ophthalmology. Journal canadien d'ophtalmologie.

[5]  P. Ellis.  Systemic Effects of Locally Applied Anticholinesterase Agents , 1966 .

[6]  W. Dettbarn,et al.  Blood cholinesterase activity of glaucoma patients treated with phospholine iodide. , 1966, American journal of ophthalmology.

[7]  J. Klayman.  Use of Long-acting Cholinesterase Agents in Glaucoma , 1966 .

[8]  P. Ellis,et al.  Echothiophate iodide therapy in children. Effect upon blood cholinesterase levels. , 1967, Archives of ophthalmology.

[9]  P. Kaufman,et al.  Loss of acute pilocarpine effect on outflow facility following surgical disinsertion and retrodisplacement of the ciliary muscle from the scleral spur in the cynomolgus monkey. , 1976, Investigative ophthalmology.

[10]  R. Gupta,et al.  Mechanisms of toxicity and tolerance to diisopropylphosphorofluoridate at the neuromuscular junction of the rat. , 1986, Toxicology and applied pharmacology.

[11]  R. Jones,et al.  Effect of topically applied demecarium bromide and echothiophate iodide on intraocular pressure and pupil size in beagles with normotensive eyes and beagles with inherited glaucoma. , 1993, American journal of veterinary research.

[12]  P. Miller,et al.  The efficacy of topical prophylactic antiglaucoma therapy in primary closed angle glaucoma in dogs: a multicenter clinical trial. , 2000, Journal of the American Animal Hospital Association.