| Item |
Information |
|
Drug Groups
|
approved |
|
Description
|
Demecarium bromid is an indirect-acting parasympathomimetic agent that is used to treat glaucoma. It is a cholinesterase inhibitor or an anticholinesterase. Cholinesterase inhibitors prolong the effect of acetylcholine, which is released at the neuroeffector junction of parasympathetic postganglion nerves, by inactivating the cholinesterases that break it down. Demecarium inactivates both pseudocholinesterase and acetylcholinesterase. In the eye, this causes constriction of the iris sphincter muscle (causing miosis) and the ciliary muscle. The outflow of the aqueous humor is facilitated, which leads to a reduction in intraocular pressure. |
| Indication |
For the topical treatment of chronic open-angle glaucoma. |
| Pharmacology |
Demecarium is a long-acting cholinesterase inhibitor and potent miotic. Because of its toxicity, it should be reserved for use in patients with open-angle glaucoma or other chronic glaucomas not satisfactorily controlled with the short-acting miotics and other agents. Application of demecarium to the eye produces intense miosis and ciliary muscle contraction due to inhibition of cholinesterase, allowing acetylcholine to accumulate at sites of cholinergic transmission. These effects are accompanied by increased capillary permeability of the ciliary body and iris, increased permeability of the blood-aqueous barrier, and vasodilation. Myopia may be induced or, if present, may be augmented by the increased refractive power of the lens that results from the accommodative effect of the drug. |
| Toxicity |
The oral LD50 is 2.96 mg/kg in the mouse. Symptoms of overdose include nausea, vomiting, abdominal cramps, diarrhea, urinary incontinence, salivation, sweating, difficulty in breathing, bradycardia, or cardiac irregularities. |
| Affected Organisms |
| • |
Humans and other mammals |
|
| References |
| • |
Ward DA, Abney K, Oliver JW: The effects of topical ocular application of 0.25% demecarium bromide on serum acetylcholinesterase levels in normal dogs. Vet Ophthalmol. 2003 Mar;6(1):23-5.
[Pubmed]
|
| • |
Krohne SG: Effect of topically applied 2% pilocarpine and 0.25% demecarium bromide on blood-aqueous barrier permeability in dogs. Am J Vet Res. 1994 Dec;55(12):1729-33.
[Pubmed]
|
| • |
Gum GG, Gelatt KN, Gelatt JK, Jones R: 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. Am J Vet Res. 1993 Feb;54(2):287-93.
[Pubmed]
|
|
| External Links |
|
|