Alpha 2-adrenergic Agonists

Alpha-adrenergic agonists are a class of sympathomimetic medications that selectively stimulate the alpha adrenergic receptors.

  • Both clonidine and guanfacine are centrally acting alpha 2-adrenergic agonists
  • Alpha 2-adrenergic agonists have agonist effects on presynaptic 2- adrenergic autoreceptors, resulting (through negative feedback) in decreased release of norepinephrine (NE), especially in the locus ceruleus and prefrontal cortex
    • Clonidine binds to all three alpha 2-adrenergic receptor subtypes (2A, 2B, 2C) and other receptors (a1- and beta- adrenergic, histamine, imidazoline)
    • Guanfacine binds more selectively to the alpha 2A receptor.[1]
  • Within child and adolescent psychiatry, there are indications for:
  • Weakness 10%, anorexia, nausea and vomitting, dry mouth (xerostomia) <40%, hypotension (orthostatic) 1-10%