Timolol is NOT a selective Beta-1 blocker. Which option correctly describes this?

• A. Alpha-1 blocker
• B. Alpha-2 blocker
• C. Beta-1 selective blocker
• D. Non-selective beta blocker

Answer: (D)

Timolol is testing receptor selectivity for beta blockers. It blocks both beta-1 and beta-2 receptors, not just beta-1, which makes it a non-selective beta blocker. That means it affects the heart (beta-1) and the lungs/vascular smooth muscle (beta-2), unlike beta-1 selective blockers that predominantly affect the heart with fewer bronchial or vascular effects. Alpha-1 or Alpha-2 blockers describe entirely different receptor targets, so they don’t fit. A beta-1 selective blocker would be incorrect because timolol does not limit its action to beta-1 receptors.