Which drug has more alpha 1 activity, Brimonidine or Apraclonidine?

The correct choice identifies Apraclonidine as having more alpha-1 activity compared to Brimonidine. While both Brimonidine and Apraclonidine are alpha-2 adrenergic agonists primarily used in the management of glaucoma, their profiles differ in terms of alpha-1 activity.

Apraclonidine has some inherent alpha-1 agonist activity in addition to its primary effect as an alpha-2 agonist. This characteristic allows it to potentially cause vasoconstriction and decrease blood flow in the eye, which can lead to a rise in the efficacy of lowering intraocular pressure but may also contribute to side effects like conjunctival blanching.

Brimonidine, on the other hand, primarily functions as an alpha-2 adrenergic agonist and is much more selective. It has significantly less affinity for alpha-1 receptors, which reduces its chances of producing the vasoconstriction and side effects associated with alpha-1 activity.

Thus, Apraclonidine is recognized for having more alpha-1 receptor activity compared to Brimonidine, making it the correct answer for the question regarding which drug exhibits greater alpha-1 activity.