| Candidate ID: | R0166 |
| Source ID: | DB00484 |
| Source Type: | approved |
| Compound Type: |
small molecule
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| Compound Name: |
Brimonidine
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| Synonyms: |
5-Bromo-6-(2-imidazolin-2-ylamino)quinoxaline; Bromoxidine
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| Molecular Formula: |
C11H10BrN5
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| SMILES: |
BrC1=C(NC2=NCCN2)C=CC2=NC=CN=C12
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| Structure: |
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| DrugBank Description: |
Brimonidine is an alpha-adrenergic agonist and 2-imidazoline derivative that was first introduced in 1996. It is considered to be a third generation alpha-2 aadrenergic receptor agonist, since it displays preferential binding at alpha-2 adrenoceptors over alpha-1 receptors. Brimonidine displays a higher selectivity toward the alpha-2 adrenergic receptors than or , which are also alpha-2 adrenergic agonists. Alpha-2 adrenergic agonists are members of the ocular hypotensive agent drug class that are used in the chronic treatment of glaucoma. Early treatment and management of glaucoma, which predominantly involves the lowering of intraocular pressure, is critical since glaucoma is considered to be a common cause of blindness worldwide.
Ophthalmically, brimonidine is used to lower intraocular pressure by reducing aqueous humor production and increasing uveoscleral outflow. Because it is oxidately stable, brimonidine is associated with fewer reports of ocular allergic reactions compared to other alpha-2 adrenergic agonists. The ophthalmic solution of brimonidine was first approved by the FDA in 1996 as Alphagan and brimonidine is the only selective alpha-adrenergic receptor agonist approved for chronic treatment in glaucoma. Brimonidine is also found in ophthalmic solutions in combination with under the market name Simbrinza for the reduction in intraocular pressure. Unlike nonselective beta-blockers used in ocular hypertension, brimonidine is not associated with significantly adverse cardiopulmonary side effects. Thus brimonidine is an effective and safe alternative to beta-blockers, in patients with, or at high risk for, cardiopulmonary disease. The topical form of brimonidine was approved by the FDA in August 2013 for the symptomatic treatment of persistent facial erythema of rosacea in adults. It is marketed under the brand name Mirvaso. Brimonidine is the first topical treatment approved for facial erythema of rosacea.
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| CAS Number: |
59803-98-4
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| Molecular Weight: |
292.135
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| DrugBank Indication: |
**Opthalmic**
Indicated for lowering intraocular pressure (IOP) in patients with open-angle glaucoma or ocular hypertension as monotherapy or combination product with .
**Topical**
Indicated for the treatment of persistent (non-transient) facial erythema of rosacea in adults 18 years of age or older.
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| DrugBank Pharmacology: |
Brimonidine is a highly selective alpha-2 adrenergic receptor agonist that is 1000-fold more selective for the alpha2-adrenergic receptor than the alpha1-adrenergic receptor. This characteristic gives the drug some therapeutic advantages, since it reduces the risk of systemic side effects, such as systemic hypotension, bradycardia, and sedation. In addition, there is a reduction in the risk for developing alpha-1 mediated ocular unwanted effects, such as conjunctival blanching, mydriasis, and eyelid retraction. However, despite high alpha-2 receptor specificity, brimonidine may still produce alpha-1 adrenoceptor-mediated ocular effects, such as conjunctival vasoconstriction. Brimonidine has a peak ocular hypotensive effect occurring at two hours post-dosing. In a randomized, double-blind clinical study, ocular administration of 0.2% brimonidine in healthy volunteers resulted in a 23% reduction of mean intraocular pressure from baseline at 3 hours following administration. In comparative studies consisting of patients with open-angle glaucoma or ocular hypertension, the ocular hypotensive effect of brimonidine was maintained during treatment periods of up to 1 year.
Brimonidine mediates vasoconstrictive effects and it was shown to exhibit anti-inflammatory properties in _ex vivo_ human skin model and _in vivo_ inflammation models. In a clinial trials consisting of adults with moderate to severe facial erythema of rosacea, brimonidine was shown to improve the extent of redness at 3 hours after application, compared to placebo. It was shown to be a potent vasoconstrictor of human subcutaneous vessels with a diameter of less than 200 µm. In _in vivo_ mouse inflammation models, brimonidine displayed anti-inflammatory properties by inhibiting edema. In a randomized, double-blind study, brimonidine reduced erythema for the 12 hours of the study in a dose-dependent manner.
When adminsitered systemically, brimonidine was shown to cause cardiovascular effects by decreasing blood pressure, decreasing heart and respiratory rate, and prolonging the PR interval in the electrocardiogram. This is due to the targeting of adrenoceptors by the drug. Although the clinical significance has not been established, there is evidence that brimonidine exhibits neuroprotective activity in experimental models of cerebral ischemia and optic nerve injury. _In vitro_ studies show that brimonidine mediated protective effects on neuronal cells from kainate acid insult and on cultured retinal ganglion cells from glutamate-induced cytotoxicity, which is a possible mediator of secondary neuronal degeneration in human glaucoma. Neuroprotective actions of brimonidine were also demonstrated in rat models of acute retinal ischemia and chronic IOP elevation. It has been proposed that brimonidine may exert neuroprotective effects on the retina and optic nerve by enhancing intrinsic retinal ganglion cell survival mechanisms and/or induction of neuronal survival factors, such as bFGF. However, further investigations are needed to conclude on these possible therapeutic benefits of the drug.
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| DrugBank MoA: |
In the eye, alpha-1 adrenoceptors play a role in vasoconstriction, mydriasis, eyelid retraction, and elevation of intraocular pressure (IOP) whereas alpha-2 adrenoceptors are responsible for IOP reduction via a complex Gi-coupled signaling cascade pathway. Activation of alpha-2 receptors leads to inhibition of adenylyl cyclase and reduction of cyclic AMP levels. As a result, there is a decrease in norpinephrine (NE) release at the synaptic junction, NE-induced stimulation of beta-2 adrenoceptors, and production of aqueous humor by the ciliary epithelium. An elevated IOP is the most significant risk factor for developing glaucomatous optic neuropathy, which is associated with progressive visual field loss and functional disability if left untreated. Regardless of the etiology of the disease, the aim of current therapies for glaucoma is to reduce IOP, as reduction of IOP significantly reduces the risk of progression of vision loss even when IOP is already within the normal range. When administered ophthalmically, brimonidine is rapidly absorbed into the eye, acts as an agonist at ocular alpha-2 adrenoceptors and lowers IOP via a dual mechanism of action. It is proposed that initial dosing of the drug causes a reduction in aqueous humour production and chronic dosing leads to an increase in uveoscleral outflow. Brimonidine does not affect episcleral venous pressure. By reducing IOP, brimonidine aims to reduce the likelihood of glaucomatous visual field loss in ocular hypertension, and slow the progression of visual field defect in established open-angle glaucoma. When applied topically on skin, brimonidine reduces erythema through direct vasocontriction of small arteries and veins. As brimonidine mediates a potent peripheral vasoconstrictive activity by selectively working on the alpha-2 adrenoceptors, the use of brimonidine is thought to be efficacious for the treatment of facial erythema of rosacea, which is thought to arise from vasomotor instability and abnormal vasodilation of the superficial cutaneous vasculature of the face.
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| Targets: |
Alpha-2A adrenergic receptor agonist; Alpha-2B adrenergic receptor agonist; Alpha-2C adrenergic receptor agonist
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| Inclusion Criteria: |
Therapeutic strategy associated
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