Vistagan

Uses

Vistagan ophthalmic solution has been shown to be effective in lowering intraocular pressure and may be used in patients with chronic open-angle glaucoma or ocular hypertension.

Vistagan is also used to associated treatment for these conditions: Ocular Hypertension, Open-angle Glaucoma (OAG)

How Vistagan works

Vistagan's mechanism of action in reducing IOP is not clearly defined, but is believed to be due to a reduction of the production of aqueous humor via blockage of endogenous catecholamine-stimulated increases in cyclic adenosine monophosphate (AMP) concentrations within the ciliary processes.

Dosage

Vistagan dosage

The recommended starting dose is one to two drops of Levobunolo ophthalmic solution 0.5% in the affected eye(s) once a day. Typical dosing with Vistagan 0.25% is one to two drops twice daily. In patients with more severe or uncontrolledglaucoma, Levobunolo 0.5% can be administeredb.i.d.As with any new medication, careful monitoring of patients is advised. Dosages above one drop of Vistagan 0.5% b.i.d. are not generally more effective. If the patient'sIOPis not at a satisfactory level on this regimen, concomitant therapy with dipivefrin and/orepinephrine, and/or pilocarpine and other miotics, and/or systemically administered carbonic anhydrase inhibitors, such as acetazolamide, can be instituted. Patients should not typically use two or more topical ophthalmic beta-adrenergic blocking agents simultaneously.

Side Effects

Common side effects are ocular stinging, burning, blepharoconjunctivitis, blepharitis, decreased visual acuity, band keratopathy, erythema, iridocyclitis, conjunctivitis and itching sensation; bradycardia, CVA, syncope, arrhythmia, heart block, hypotension, cerebral ischaemia, bronchospasm. Rarely, reduced corneal sensitivity and tearing.

Toxicity

Bradycardia, hypotension, bronchospasm, and acute cardiac failure, LD₅₀=700 mg/kg (orally in rat).

Precaution

Patients with diminished pulmonary function, nonallergic bronchospasm, inadequate cardiac function, DM, myasthenia gravis. May mask signs and symptoms of hypoglycaemia and hyperthyroidism. Avoid abrupt withdrawal as it may precipitate thyroid storm. Pregnancy and lactation.

Interaction

Additive hypotensive effect with catecholamine-depleting drug (e.g. reserpine), Ca channel blockers, β-adrenergic blockers, digitalis glycosides, antiarrhythmics, guanethidine, parasympathomimetics. Mydriasis may occur when used with epinephrine.

Food Interaction

Elimination Route

80%

Half Life

20 hours

Pregnancy & Breastfeeding use

There are no adequate and well-controlled studies in pregnant women. Vistagan ophthalmic solution should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

It is not known whether this drug is excreted in human milk. Systemic beta-blockers and topical timolol maleate are known to be excreted in human milk. Caution should be exercised when Vistagan is administered to a nursing woman.

Contraindication

Vistagan ophthalmic solution is contraindicated in those individuals with bronchial asthma, or with a history of bronchial asthma, or severe chronic obstructive pulmonary disease; sinus bradycardia; second and third degree atrioventricular block; overt cardiac failure; cardiogenic shock; or hypersensitivity to any component of these products.

Special Warning

Pediatric Use: Safety and effectiveness in pediatric patients have not been established.

Geriatric Use: No overall differences in safety or effectiveness have been observed between elderly and younger patients.

Acute Overdose

No data are available regarding overdosage in humans. Should accidental ocular overdosage occur, flush eye(s) with water or normal saline. If accidentally ingested, efforts to decrease further absorption may be appropriate (gastric lavage). The most common signs and symptoms to be expected with overdosage with administration of a systemic beta-adrenergic blocking agent are symptomatic bradycardia, hypotension, bronchospasm, and acute cardiac failure. Should these symptoms occur, discontinue Vistagan therapy and initiate appropriate supportive therapy. The following supportive measures should be considered:

Symptomatic bradycardia: Use atropine sulfate intravenously in a dosage of 0.25 mg to 2 mg to induce vagal blockade. If bradycardia persists, intravenous isoproterenol hydrochloride should be administered cautiously. In refractory cases the use of a transvenous cardiac pacemaker should be considered.

Hypotension: Use sympathomimetic pressor drug therapy, such as dopamine, dobutamine or levarterenol. In refractory cases the use of glucagon hydrochloride may be useful.

Bronchospasm: Use isoproterenol hydrochloride. Additional therapy with aminophylline may be considered.

Acute cardiac failure: Conventional therapy with digitalis, diuretics and oxygen should be instituted immediately. In refractory cases the use of intravenous aminophylline is suggested. This may be followed, if necessary, by glucagon hydrochloride which may be useful.

Heart block (second or third degree): Use isoproterenol hydrochloride or a transvenous cardiac pacemaker.

Innovators Monograph

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