Why are beta-blockers not dosed at bedtime (QHS)?

• A. doesn't work at night
• B. causes nocturnal hypotension
• C. more systemic side effects at night
• D. their stability is compromised at night

Answer: (A)

Beta-blockers lower intraocular pressure mainly by reducing aqueous humor production. This production follows a circadian pattern and is naturally lower at night, so adding a beta-blocker at bedtime doesn’t yield much extra IOP reduction. Dosing in the morning takes advantage of higher daytime production and helps blunt the typical daytime IOP rise, making the medication more effective. While nocturnal systemic side effects can be a safety consideration with these drugs, that doesn’t explain the diminished night-time effect and isn’t the reason for not dosing at night.