Which of the following systemic medications is considered an Alpha 2 adrenergic agonist?

• A. Isoproterenol
• B. Albuterol
• C. Clonidine
• D. Salmeterol

Answer: (C)

Alpha-2 adrenergic agonists work by dampening sympathetic outflow, mainly through activation of alpha-2 receptors in the central nervous system, which lowers peripheral vascular resistance and blood pressure. Clonidine fits this mechanism, as it activates CNS alpha-2 receptors to reduce sympathetic tone, producing antihypertensive effects (and also used in other settings like withdrawal management). The other drugs here act on beta receptors instead: isoproterenol is a nonselective beta agonist that increases heart rate and bronchodilation; albuterol and salmeterol are beta-2 agonists used for bronchodilation. Since they do not activate alpha-2 receptors, they are not alpha-2 adrenergic agonists.