Timolol is an effective medication for reducing intraocular pressure in patients with glaucoma. The recommended starting dose is one drop of timolol 0.25% ophthalmic solution in the affected eye(s) twice daily. It is a non-selective beta-blocker.
Ophthalmic administration does not prevent systemic absorption and effects. In patients with significant hypotension, falls, or bradycardia of unknown origin, timolol should be considered as a potential contributor. Timolol is contraindicated in patients with a second- or third-degree atrioventricular heart block, overt cardiovascular failure, or cardiogenic shock. While rare, severe cardiovascular effects, including death, have been associated with the ophthalmic use of timolol. Use caution in patients taking oral beta-blockers and other antihypertensive agents.
If a patient’s glaucoma is well controlled with ophthalmic timolol, but they are experiencing hypotension and dizziness, there are a variety of options to mitigate the adverse effects. One option being, place a finger over the tear duct to prevent systemic absorption. This method may not be convenient for everyone, as you should cover the tear duct for 2-3 minutes.
Another option is timolol gel-forming ophthalmic drops. While the gel-forming drops can still lead to systemic absorption, the amount absorbed is usually less. The gel-forming drops provide an extended-release of the medication, allowing for once a day dosing. The average peak plasma concentration of timolol XR 0.5% gel-forming solution is 0.28 ng/mL following morning dosing, whereas peak concentrations of 0.35-0.88 ng/mL were associated with timolol 0.5% ophthalmic solution. One downfall of this formulation is increased blurred vision upon application. As the gel forms on the patient’s eye, it can obstruct vision until the product is absorbed.
Finally, a safer option to consider is switching the patient to latanoprost or an alternative anti-glaucoma agent. Latanoprost has not been shown to have systemic cardiovascular effects and is not contraindicated in patients with cardiovascular dysfunction. Latanoprost is used once daily at bedtime, reducing the amount of time the patient needs to spend administering their eye drops.
While the systemic effect of timolol eye drops is likely going to be much less significant compared to taking an oral beta-blocker, it shouldn’t be overlooked in a patient with significant hypotension or bradycardia.
Article was written by Taylor Gill in collaboration with Eric Christianson, PharmD.
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Abbas SA, Hamadani SM, Ahmad U, Desai A, Kitchloo K. Ophthalmic Timolol and Hospitalization for Symptomatic Bradycardia and Syncope: A Case Series. Cureus. 2020;12(3):e7270. Published 2020 Mar 14.
Pratt NL, Ramsay EN, Kalisch Ellett LM, Nguyen TA, Roughead EE. Association between Ophthalmic Timolol and Hospitalisation for Bradycardia. J Ophthalmol. 2015;2015:567387.
Product Information: ISTALOL(R) ophthalmic solution, timolol maleate 0.5% ophthalmic solution. ISTA Pharmaceuticals, Inc. (per FDA), Irvine, CA, 2013.