Antihistamines

Question 1

Chlorpheniramine

Answer 1

• 1st generation antihistamine that acts by blocking both central and peripheral H1 receptors

because they easily penetrate the blood-brain barrier and accumulate in the CNS.

• most sedating of this generation of antihistamines are diphenhydramine (Benadryl), promethazine, and hydroxyzine. Despite the associated sedation, these antihistamines are often still used to prevent/treat allergic reactions and motion sickness and as antiemetics.

Question 2

Loratadine

Answer 2

second-generation antihistamine that blocks peripheral H1 histamine receptors. It does not enter the CNS and does not cause drowsiness.