This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Adrenergic System, Subject name: Pharmacology
Alpha 2 agonists cause all of the following except: 
Select and explain. 
A. Analgesia, B. Hyperalgesia, C. Sedation, D. Anxiolysis
B: Hyperalgesia
Answer: B: Hyperalgesia 
Explanation: Ans. (B) Hyperalgesia(Ref: Goodman and Gilman 12th/296; Katzung 12th/176; KDT 8th/e p140)* Alpha 2 agonists cause analgesia, not the hyperalgesia.* Clonidine is used for treatment of hypertension. It decreases blood pressure by acting on central alpha 2 adrenergic receptors.* Dexmedetomidine is another alpha 2 receptor agonist that is used to produce sedation and anxiolytic state by action on alpha 2 receptors in the brain. It can also produce analgesia by acting on alpha 2 receptors in spinal cord.