Review Question - QID 210364

A 22-year-old woman presents to her primary care physician in April for seasonal allergies. She has suffered from seasonal allergies for the past 2 years and takes diphenhydramine as needed when her symptoms worsen. She has not yet seen a physician for her allergies. She reports that diphenhydramine has been helpful in controlling her symptoms, but she does not like feeling drowsy from the medication. Her past medical history is also notable for well-controlled asthma. She uses an albuterol inhaler on an as-needed basis. She smokes marijuana daily. Her temperature is 99.2°F (37.3°C), blood pressure is 120/70 mmHg, pulse is 76/min, and respirations are 16/min. She has a prominent nasal crease. Her nasal turbinates are boggy and bluish-gray. She has copious thin and watery nasal mucus. The physician suggests replacing diphenhydramine with fexofenadine to improve her drowsiness. What characteristic of fexodenadine allows it to be less sedating than diphenhydramine?