BRIMOCHEK -T EYE DROPS SOLUTION

Brimonidine
Timolol

Source of information: Drugbank (External Link). Last updated on: 3rd July 18
*Trade Name used in the content below may not be the same as the HSA-registered product.

Active Ingredient / Synonyms

5-Bromo-6-(2-imidazolin-2-ylamino)quinoxaline | Brimonidina | Brimonidine | Brimonidinum | Bromoxidine | Brimonidine |

Description

Brimonidine is a drug used to treat glaucoma. It acts via decreasing aqueous humor synthesis. A topical gel formulation, marketed under the name Mirvaso, was FDA approved on August 2013 for the treatment of rosacea.

Indication

The ophthalmic solution is indicated for patients with open-angle glaucoma or ocular hypertension to lower intraocular pressure. The topical gel is indicated for the treatment of persistent (nontransient) facial erythema of rosacea in adults 18 years or older.

Mechanism of Action

Brimonidine is an alpha adrenergic receptor agonist (primarily alpha-2). It has a peak ocular hypotensive effect occurring at two hours post-dosing. Fluorophotometric studies in animals and humans suggest that Brimonidine has a dual mechanism of action by reducing aqueous humor production and increasing uveoscleral outflow. The topical gel reduces erythema through direct vasocontriction.

Pharmacodynamics

Brimonidine significantly lowers intraocular pressure with minimal effects on cardiovascular and pulmonary parameters. It lowers intraocular pressure by reducing aqueous humor production and increasing uveoscleral outflow.

Pharmacokinetics

Absorption:

Minimal systemic absorption occurs after ocular insertion. When the topical gel was applied to adult patients with facial erythema associated with rosacea, the plasma maximum concentration (Cmax) and area under the concentration-time curve (AUC) were 46 ± 62 pg/mL and 417 ± 264 pg.hr/mL, respectively. These values were reached on Day 15 of treatment.

Distribution:

Not Available

Metabolism:

Metabolized primarily by the liver.

Elimination:

Urinary excretion is the major route of elimination of the drug and its metabolites.

Half-life

2 hours [ophthalmic solution]

Clearance

Not Available

Toxicity

Oral LD50 is 50 mg/kg in mice and 100 mg/kg in rats. Common adverse reactions of the topical gel formulation include erythema, flushing, skin burning sensation, and contact dermatitis.

Source of information: Drugbank (External Link). Last updated on: 3rd July 18
*Trade Name used in the content below may not be the same as the HSA-registered product.

Active Ingredient / Synonyms

(S)-1-(tert-butylamino)-3-[(4-morpholin-4-yl-1,2,5-thiadiazol-3-yl)oxy]propan-2-ol | Timolol | Timolol anhydrous | Timololo | Timololum | Timolol |

Description

A beta-adrenergic antagonist similar in action to propranolol. The levo-isomer is the more active. Timolol has been proposed as an antihypertensive, antiarrhythmic, antiangina, and antiglaucoma agent. It is also used in the treatment of migraine disorders and tremor. [PubChem]

Indication

In its oral form it is used to treat high blood pressure and prevent heart attacks, and occasionally to prevent migraine headaches. In its opthalmic form it is used to treat open-angle and occasionally secondary glaucoma.

Mechanism of Action

Like propranolol and nadolol, timolol competes with adrenergic neurotransmitters such as catecholamines for binding at beta(1)-adrenergic receptors in the heart and vascular smooth muscle and beta(2)-receptors in the bronchial and vascular smooth muscle. Beta(1)-receptor blockade results in a decrease in resting and exercise heart rate and cardiac output, a decrease in both systolic and diastolic blood pressure, and, possibly, a reduction in reflex orthostatic hypotension. Beta(2)-blockade results in an increase in peripheral vascular resistance. The exact mechanism whereby timolol reduces ocular pressure is still not known. The most likely action is by decreasing the secretion of aqueous humor.

Pharmacodynamics

Similar to propranolol and nadolol, timolol is a non-selective, beta-adrenergic receptor antagonist. Timolol does not have significant intrinsic sympathomimetic, direct myocardial depressant, or local anesthetic (membrane-stabilizing) activity, but does possess a relatively high degree of lipid solubility. Timolol, when applied topically to the eye, has the action of reducing elevated, as well as normal, intraocular pressure, whether or not accompanied by glaucoma. Elevated intraocular pressure is a major risk factor in the pathogenesis of glaucomatous visual field loss and optic nerve damage.

Pharmacokinetics

Absorption:

Bioavailability is about 60%

Distribution:

Not Available

Metabolism:

Primarily hepatic (80%) via the cytochrome P450 2D6 isoenzyme.

Elimination:

Timolol and its metabolites are primarily excreted in the urine.

Half-life

2.5-5 hours

Clearance

Not Available

Toxicity

LD50=1190 mg/kg (oral, mice), LD50=900 mg/kg (oral, rat). Symptoms of overdose include drowsiness, vertigo, headache, and atriventricular block.

References

  1. Health Science Authority of Singapore - Reclassified POM
  2. Drugbank

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Approval Information

BRIMOCHEK -T EYE DROPS SOLUTION was registered with Health Science Authority of Singapore by DCH AURIGA SINGAPORE. It is marketed with the registration number of SIN15191P with effective from 2017-03-09.

This product contains 2mg/ml of Brimonidine, and 5mg/ml of Timolol in the form of SOLUTION, STERILE.

The medicine was manufactured by Indoco Remedies LTD (Plant II) in INDIA

It is a Presciption Only Medicine which can only be obtained from a doctor or a dentist, or from a pharmacist with a prescription from a Singapore-registered doctor or dentist.

Anatomical Therapeutic Chemical (ATC) Classification

ATC Code: S01ED51

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46 APO-PROPRANOLOL TABLET 10mg Propranolol POM PHARMAFORTE SINGAPORE PTE LTD Active
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508 APO-SULFATRIM PEDIATRIC TABLET Sulfamethoxazole|Trimethoprim POM PHARMAFORTE SINGAPORE PTE LTD Active
526 B.S. SUSPENSION Sulfamethoxazole|Trimethoprim POM APEX PHARMA MARKETING PTE LTD Active
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