Certification of Pharmacy Technicians (ExCPT) Practice Exam

Which of the following drugs is NOT an antihistamine?

1. Diphenhydramine

2. Paroxetine

3. Desloratadine

4. Cetirizine

The correct answer is: Paroxetine

Paroxetine is not an antihistamine; it is classified as a selective serotonin reuptake inhibitor (SSRI). SSRIs are primarily used to treat depression and anxiety disorders by increasing serotonin levels in the brain. In contrast, antihistamines, such as diphenhydramine, desloratadine, and cetirizine, are primarily used to relieve symptoms associated with allergies, such as nasal congestion, sneezing, and itching, by blocking the action of histamine in the body. Diphenhydramine is a first-generation antihistamine known for its sedative properties and is commonly used for allergic reactions and as a sleep aid. Desloratadine and cetirizine are both second-generation antihistamines designed to provide relief from allergy symptoms with fewer sedative effects, allowing for better tolerability during daytime activities. Thus, the distinction lies in the primary pharmacological action of paroxetine as an antidepressant, in contrast to the allergy-relief functions of the others listed.