Cardiovascular effects of topical beta-blockers during exercise

Area of Science:

• Ophthalmology
• Cardiovascular Physiology
• Pharmacology

Background:

• Ophthalmic beta-blockers are frequently prescribed for glaucoma.
• Understanding their systemic cardiovascular effects during physiological stress is crucial.

Purpose of the Study:

• To compare the cardiovascular effects of single-instillation ocular betaxolol and timolol during treadmill exercise.

Main Methods:

• A double-masked, three-way crossover study involving 24 healthy individuals.
• Comparison of betaxolol 1%, timolol 0.5%, and placebo after single ocular instillation.
• Cardiovascular parameters (heart rate, blood pressure) measured during 10-minute treadmill exercise.

Main Results:

• Betaxolol showed no significant difference in heart rate or double product compared to placebo.
• Timolol significantly reduced heart rate and double product (P < .05) versus placebo and betaxolol.
• No significant differences in mean arterial pressure were observed across treatments.

Conclusions:

• Ocular timolol, but not betaxolol, exerts significant cardiovascular effects during exercise.
• This highlights potential systemic implications of topical beta-blocker use.