Systemic beta-blockade with once daily Betimol or Timoptic-XE

Area of Science:

• Ophthalmology
• Cardiovascular Physiology
• Pharmacology

Background:

• Timolol is a beta-blocker commonly used in ophthalmic solutions to manage glaucoma.
• Systemic absorption of topical timolol can occur, potentially affecting cardiovascular parameters.
• Evaluating the systemic effects of different timolol formulations is crucial for patient safety and efficacy.

Purpose of the Study:

• To compare the systemic beta-blockade activity of timolol hemihydrate 0.5% (Betimol) and timolol maleate gel forming solution 0.5% (Timoptic-XE) when administered once daily.
• To assess the impact of these treatments on exercise performance metrics.

Main Methods:

• A randomized, three-period crossover study involving 14 healthy subjects.
• Participants received placebo, timolol hemihydrate, or timolol maleate gel forming solution daily for three days prior to exercise testing.
• Exercise testing was conducted two hours post-dosing, with measurements of maximum heart rate, time to exhaustion, and double product.

Main Results:

• No statistically significant difference in maximum exercise heart rate was observed between timolol hemihydrate and timolol maleate gel forming solution.
• Both timolol formulations significantly reduced heart rate and double product compared to placebo.
• Time to exhaustion did not differ between treatment groups.

Conclusions:

• Once-daily dosing of timolol hemihydrate and timolol maleate gel forming solution results in similar systemic beta-blockade activity.
• Both formulations effectively reduce cardiovascular response to exercise compared to placebo.
• Further monitoring is warranted, as one subject experienced heart block with timolol maleate gel forming solution.