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Istalol®

GoodRx

Timolol Maleate 0.5% · ophthalmic solution

Antiglaucoma

Indication
ISTALOL is a beta adrenergic blocker indicated for the treatment of elevated intraocular pressure in patients with ocular hypertension or open-angle glaucoma.
Contraindications
  • Bronchial asthma, a history of bronchial asthma, severe chronic obstructive pulmonary disease
  • Sinus bradycardia, second or third degree atrioventricular block, overt cardiac failure, cardiogenic shock
  • Hypersensitivity to any component of this product.
Available Forms
0.5% solution: 5 mL in a 10 mL container; 2.5 mL in a 7.5 mL container
Mechanism of Action
Timolol maleate is a beta 1 and beta 2 (non-selective) adrenergic receptor blocking agent that does not have significant intrinsic sympathomimetic, direct myocardial depressant, or local anesthetic (membrane-stabilizing) activity. Beta-adrenergic receptor blockade reduces cardiac output in both healthy subjects and patients with heart disease. In patients with severe impairment of myocardial function, beta-adrenergic receptor blockade may inhibit the stimulatory effect of the sympathetic nervous system necessary to maintain adequate cardiac function. The precise mechanism of the ocular hypotensive action of ISTALOL is not clearly established at this time. Tonography and fluorophotometry studies in man suggest that its predominant action may be related to reduced aqueous formation. However, in some studies a slight increase in outflow facility was also observed.
Dosage
One drop of ISTALOL should be administered in the affected eye(s) once a day in the morning (AM). If more than one topical ophthalmic drug is being used, the drugs should be administered at least five minutes apart.
Warnings & Precautions
  • Potentiation of Respiratory Reactions Including Asthma: Although administered topically, timolol maleate can be absorbed systemically, so the adverse reactions of systemic beta-adrenergic blocking agents may occur. Severe respiratory reactions and cardiac reactions including death due to bronchospasm in patients with asthma, and rarely death in association with cardiac failure, have been reported following systemic or ophthalmic administration of timolol maleate.
  • Cardiac Failure: Sympathetic stimulation may be essential for support of the circulation in individuals with diminished myocardial contractility, and its inhibition of beta-adrenergic receptor blockade may precipitate more severe failure. In patients without a history of cardiac failure, continued depression of the myocardium with beta-blocking agents over a period of time can, in some cases, lead to cardiac failure. At the first sign or symptom of cardiac failure, ISTALOL should be discontinued.
  • Obstructive Pulmonary Disease: Patients with chronic obstructive pulmonary disease (e.g., chronic bronchitis, emphysema) of mild or moderate severity, bronchospastic disease, or a history of bronchospastic disease [other than bronchial asthma or a history of bronchial asthma in which ISTALOL is contraindicated] should, in general, not receive beta-blocking agents, including ISTALOL.
  • Increased Reactivity to Allergens: While taking beta-blockers, patients with a history of atopy or a history of severe anaphylactic reactions to a variety of allergens may be more reactive to repeated accidental, diagnostic, or therapeutic challenge with such allergens. Such patients may be unresponsive to the usual doses of epinephrine used to treat anaphylactic reactions.
  • Potentiation of Muscle Weakness: Beta-adrenergic blockade has been reported to potentiate muscle weakness consistent with certain myasthenic symptoms (e.g., diplopia, ptosis, and generalized weakness). Timolol has been reported rarely to increase muscle weakness in some patients with myasthenia gravis or myasthenic symptoms.
  • Masking of Hypoglycemic Symptoms: Beta-adrenergic blocking agents should be administered with caution in patients subject to spontaneous hypoglycemia or to diabetic patients (especially those with labile diabetes) who are receiving insulin or oral hypoglycemic agents. Beta-adrenergic receptor blocking agents may mask the signs and symptoms of acute hypoglycemia.
  • Masking of Thyrotoxicosis: Beta-adrenergic blocking agents may mask certain clinical signs (e.g., tachycardia) of hyperthyroidism. Patients suspected of developing thyrotoxicosis should be managed carefully to avoid abrupt withdrawal of beta-adrenergic blocking agents that might precipitate a thyroid storm.
  • Contamination of Topical Ophthalmic Products After Use: There have been reports of bacterial keratitis associated with the use of multiple-dose containers of topical ophthalmic products. These containers had been inadvertently contaminated by patients who, in most cases, had a concurrent corneal disease or a disruption of the ocular epithelial surface.
  • Impairment of Beta-adrenergically Mediated Reflexes: Withdrawal before major surgery is controversial. Blockade impairs the heart's response to beta-adrenergically mediated reflex stimuli and may augment the risk of general anesthesia. Protracted severe hypotension during anesthesia and difficulty in restarting and maintaining the heartbeat have been reported. Some authorities recommend gradual withdrawal before elective surgery. If necessary, effects may be reversed by sufficient doses of adrenergic agonists.
  • Angle-Closure Glaucoma: In patients with angle-closure glaucoma, the immediate objective of treatment is to reopen the angle. This may require constricting the pupil. Timolol maleate has little or no effect on the pupil. ISTALOL should not be used alone in the treatment of angle-closure glaucoma.
  • Cerebrovascular Insufficiency: Because of potential effects of beta-adrenergic blocking agents on blood pressure and pulse, these agents should be used with caution in patients with cerebrovascular insufficiency. If signs or symptoms suggesting reduced cerebral blood flow develop following initiation of therapy with ISTALOL, alternative therapy should be considered.
  • Choroidal Detachment: Choroidal detachment after filtration procedures has been reported with the administration of aqueous suppressant therapy (e.g., timolol).
  • Contact Lens Use: ISTALOL contains benzalkonium chloride, an anti-microbial preservative which may be absorbed by soft contact lenses. Contact lenses should be removed prior to administration of the solution. Lenses may be reinserted 15 minutes following ISTALOL administration.
Common Side Effects
The most frequently reported adverse reactions have been burning and stinging upon instillation in 38% of patients treated with ISTALOL. Additional reactions reported with ISTALOL at a frequency of 4% to 10% include: blurred vision, cataract, conjunctival injection, headache, hypertension, infection, itching and decreased visual acuity.
Pregnancy & Lactation
Pregnancy: There are no adequate and well-controlled studies in pregnant women with timolol maleate to inform a drug-associated risk. Administration of oral timolol maleate to pregnant mice, rats and rabbits did not produce teratogenicity at clinically relevant systemic exposures. ISTALOL should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Lactation: Timolol has been detected in human milk following oral and ophthalmic drug administration. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for ISTALOL and any potential adverse effects on the breastfed child from ISTALOL.
Pediatric Use
The safety and effectiveness of ISTALOL in pediatric patients have not been established.