Which of the following is NOT true regarding Apraclonidine?

Apraclonidine is primarily an alpha 2 adrenergic agonist, which means its main therapeutic action occurs through the stimulation of alpha 2 receptors. This stimulation leads to a reduction in aqueous humor production and an increase in uveoscleral outflow, resulting in lowered intraocular pressure (IOP). While it does have some activity at alpha 1 receptors, this is not its primary mechanism.

The other options highlight true aspects of Apraclonidine's profile. It is indeed used to acutely lower IOP, especially in situations such as acute glaucoma attacks or after certain surgical procedures. Tachyphylaxis, a phenomenon where the effectiveness of a drug diminishes with repeated use, is a notable side effect that can occur within a week or so of starting treatment with Apraclonidine. Additionally, dry mouth (xerostomia) can result due to the drug's systemic absorption and its effects on sympathetic nervous system pathways.

Therefore, the assertion that Apraclonidine primarily targets alpha 1 receptors is inaccurate, making it the correct response to the question. Understanding the receptor selectivity and mechanisms of action is crucial in ocular pharmacology, particularly for medications used to manage intraocular pressure.