Timolol
Timolol (maleate)
Timoptic (ophthalmic), Timoptic-XE (gel-forming once-daily), Istalol (once-daily 0.5%), Betimol; Blocadren (oral, discontinued in many markets); combination eye drops Combigan (with brimonidine), Cosopt (with dorzolamide)
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Summary
Common uses
Open-angle glaucoma and ocular hypertension (FDA, ophthalmic; the dominant current use)0, Hypertension (FDA, oral)0, Post-myocardial-infarction secondary prevention (FDA, oral)0, Migraine prophylaxis (FDA, oral)0
Pharmacy
Starting dose
Ophthalmic: 1 drop 0.5% in affected eye(s) BID (or once daily for XE / Istalol). Oral hypertension: 10 mg PO BID, titrate to 60 mg/day. Migraine prophylaxis: 10 mg BID, titrate to 30 mg/day
Preparations
Tablets 5, 10, 20 mg; ophthalmic solution 0.25%, 0.5%; ophthalmic gel-forming solution 0.25%, 0.5% (Timoptic-XE)
US FDA Max
60 mg/day (oral, hypertension); 0.5% BID (ophthalmic)
Pharmacology
Routes
Oral, ophthalmic
Onset
BP effect within hours (oral); IOP reduction within 30 minutes, full effect 1-2 weeks (ophthalmic)
Duration
12 hours (oral BID); 24 hours (Timoptic-XE)
Half-life
~4 hours (oral)[1]
Bioavailability
~50% (oral); systemic absorption from ophthalmic application is clinically meaningful via nasolacrimal drainage[1]
Pregnancy
Limited human data; β-blocker class effects include fetal growth restriction and neonatal bradycardia/hypoglycemia.[citation needed]
Legal status
Rx-only in US
Purported mechanism
Non-selective β1 and β2 adrenergic receptor antagonist. Ophthalmic application reduces aqueous humor production at ciliary-body β2 receptors, lowering intraocular pressure 20-30%, the basis of the glaucoma indication. Systemic oral use achieves the standard β-blocker effects on heart rate, contractility, and renin secretion.0 Systemic absorption from eye drops is clinically meaningful via nasolacrimal drainage, producing bradycardia, bronchospasm (worth considering in asthma and COPD), and hypoglycemia masking in diabetic patients. Nasolacrimal occlusion (pressing on the inner canthus for 1-2 minutes after instillation) reduces systemic exposure by approximately 70% and is the standard counseling pearl[1].
References
- ↑ 1.0 1.1 1.2 FDA Prescribing Information, Timoptic (timolol maleate ophthalmic solution), Bausch & Lomb/Merck, current revision. https://www.accessdata.fda.gov/drugsatfda_docs/label/2016/018086s068lbl.pdf