Generic Name

Timolol Maleate

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Classification

FDA Approved Indications

• Treatment of elevated intraocular pressure in open-angle glaucoma and ocular hypertension
• Prevention of migraine headaches
• Management of hypertension (systemic use)

Mechanism of Action

Timolol blocks beta-adrenergic receptors in the eye and systemically, reducing aqueous humor production in the eye and decreasing blood pressure by lowering cardiac output and inhibiting renin release.

Dosage and Administration

Adult: Typically, 1 drop in affected eye(s) twice daily for glaucoma; oral doses vary based on condition, e.g., hypertension usually 10-20 mg twice daily.

Pediatric: Use in pediatric patients is limited and should be under specialist supervision, especially for ocular conditions; systemic use is generally avoided unless prescribed.

Geriatric: Start at the lower end of dosing due to increased risk of systemic side effects; monitor closely.

Renal Impairment: Use with caution; dose adjustments may be necessary depending on severity.

Hepatic Impairment: No specific dosage adjustments recommended, but caution advised.

Pharmacokinetics

Absorption: Poorly absorbed systemically when used topically; systemic absorption varies with ocular application.

Distribution: Widely distributed; crosses the blood-brain barrier.

Metabolism: Metabolized in the liver via CYP2D6 pathway.

Excretion: Excreted in urine and feces.

Half Life: 2-5 hours systemically; longer for topical formulations like Timoptic-XE.

Contraindications

• Sinus bradycardia
• Second or third-degree atrioventricular block
• Cardiogenic shock
• Uncompensated heart failure

Precautions

• Asthma or other bronchospastic conditions
• Diabetes mellitus (may mask hypoglycemia)
• Pheochromocytoma (use with caution, typically with alpha-blockers)
• Caution in patients with peripheral vascular disease

Adverse Reactions - Common

• Burning or stinging in the eye (Common)
• Blurred vision (Common)
• Dry eyes (Common)
• Bradycardia (Uncommon)

Adverse Reactions - Serious

• Bronchospasm in susceptible patients (Rare)
• Systemic hypotension leading to dizziness or syncope (Rare)
• Heart failure exacerbation (Rare)
• Severe allergic reactions (Rare)

Drug-Drug Interactions

• Other antihypertensives, diuretics, antiarrhythmics, calcium channel blockers, digitalis preparations, monoamine oxidase inhibitors

Drug-Food Interactions

• No significant food interactions reported

Drug-Herb Interactions

• Caution with herbal supplements affecting blood pressure or heart rate, e.g., hawthorn, ginseng

Nursing Implications

Patient/Family Teaching

• Instruct patients to avoid stopping the medication abruptly.
• Report symptoms like shortness of breath, dizziness, or slow heart rate.
• Use eye drops exactly as prescribed, and do not touch tip of the bottle to eye.
• Inform about potential systemic effects.
• Sun protection advisable as eye drops may increase light sensitivity.

Special Considerations

Black Box Warnings:

• Use with caution in patients with asthma or other bronchospastic diseases due to risk of severe bronchospasm.

Genetic Factors: Metabolism via CYP2D6; poor metabolizers may have increased systemic effects.

Lab Test Interference: May interfere with some tests for catecholamine levels or hormone assays.

Overdose Management

Signs/Symptoms: Bradycardia, hypotension, bronchospasm, hypoglycemia, dizziness.

Treatment: Supportive care, atropine for severe bradycardia, vasopressors for hypotension, airway management for bronchospasm, intravenous glucose for hypoglycemia.

Storage and Handling

Storage: Store at room temperature away from light and moisture.

Stability: Stable until expiration date on packaging.