What is the typical dosing frequency for alpha-2 agonists in glaucoma therapy?

• A. Twice daily or three times daily
• B. Four times daily
• C. Once daily
• D. Twice weekly

Answer: (A)

Alpha-2 adrenergic agonists used in glaucoma lower intraocular pressure mainly by reducing aqueous humor production, with some additional, smaller effect on outflow. Because their effect doesn’t extend well beyond a half-day to a full day, they are typically given twice daily to maintain a steady IOP drop over 24 hours. In some cases, three times daily may be used to achieve further lowering when targets are difficult to reach or in certain regimens. Dosing more often than three times daily isn’t common due to practicality and a higher risk of systemic side effects, while once-daily dosing generally doesn’t provide adequate 24-hour control. Four times daily was used with older agents but isn’t standard for chronic therapy today.