Is it permissible to Rx two different PGAs, a beta-blocker, a CAI, and an alpha agonist at the same time?

• A. Yes
• B. No
• C. Only in emergencies
• D. Only under supervision

Answer: (B)

Two prostaglandin analogs share the same way of lowering IOP by increasing uveoscleral outflow, so using two of them at the same time typically doesn’t give much extra pressure reduction. It also means more drops, more preservatives, and a higher chance of local side effects like conjunctival hyperemia or eyelid changes, without a proportional benefit. In glaucoma therapy, you can combine a prostaglandin analog with other drug classes that work through different mechanisms (beta-blockers, carbonic anhydrase inhibitors, or alpha agonists) to achieve additive IOP lowering. So, while adding a beta-blocker, a CAI, or an alpha agonist to a single PGA is common, duplicating the prostaglandin class itself is not recommended. If more control is needed after a single PGA, the better approach is to switch to another PGA or add a different mechanism rather than a second PGA.