Antihistamine Classes
Antihistamines are divided into first-generation and second-generation categories. This distinction is important because it affects side effect profiles and patient counseling.
First-Generation Antihistamines
Diphenhydramine (Benadryl) is the most well-known first-generation antihistamine. These older antihistamines are effective but commonly cause drowsiness and sedation. This sedating effect makes diphenhydramine useful as an OTC sleep aid, but patients should be cautioned about driving and operating machinery.
Second-Generation Antihistamines
Cetirizine (Zyrtec), loratadine (Claritin), and fexofenadine (Allegra) are second-generation antihistamines that are less likely to cause drowsiness. They are commonly used for seasonal allergies and are available over the counter. Cetirizine may still cause some drowsiness in certain patients.
Nasal Corticosteroids
Fluticasone nasal spray (Flonase) and triamcinolone nasal spray (Nasacort) are OTC nasal corticosteroids used for allergy symptoms. They are applied directly to the nasal passages and are considered first-line treatment for nasal allergy symptoms by many healthcare providers.
Epinephrine Auto-Injectors
Epinephrine (EpiPen) is used for severe allergic reactions (anaphylaxis). This is a critical emergency medication that patients at risk for anaphylaxis carry with them. Pharmacy technicians should be familiar with this product and its purpose.
Exam Relevance
For the PTCE, know the difference between first and second-generation antihistamines, recognize common brand/generic pairs, understand the OTC status of most allergy medications, and be aware of the purpose of epinephrine auto-injectors. The drowsiness distinction between generations is a frequently tested concept.