Answer to Question 1
Correct Answer: 4
Rationale 1: Fexofenadine is not appropriate for use in an emergency.
Rationale 2: Azelastine is not appropriate for use in an emergency.
Rationale 3: Loratadine is not appropriate for use in an emergency.
Rationale 4: Benadryl (diphenhydramine) is the preparation most likely to be used, as it can be administered by intravenous route.
Global Rationale: Antihistamines are used as adjuncts to the emergency treatment of anaphylaxis, which is the most severe form of allergic reaction. Fexofenadine and loratadine are available only in oral forms, so are not appropriate for emergency use. Azelastine is available in a nasal mist, but this route is not useful in an emergency situation. Diphenhydramine is available in an intravenous preparation which makes emergency use possible.
Answer to Question 2
Correct Answer: 4
Rationale 1: Hydroxyzine (Atarax) is a sedating first-generation antihistamine.
Rationale 2: Cetirizine (Zyrtec) is more sedating than other second-generation agents.
Rationale 3: Diphenhydramine (Benadryl) is a sedating first-generation antihistamine.
Rationale 4: Fexofenadine (Allegra) is the least sedating of the second-generation antihistamines.
Global Rationale: First generation antihistamines like hydroxyzine and diphenhydramine have sedation as a significant adverse effect. This effect is lessened in the second generation antihistamines such as cetirizine and fexofenadine. Cetirizine appears to be somewhat more sedating than other second-generation agents.
Diagnostic Imaging Procedures and Conditions Diagnosed or Treated
Mechanism of the biotin-dependent pyruvate carboxylase reaction Phase II
Free energy diagrams for the simple reaction A ----> B
Reaction mechansim for glyceraldehyde-3-phosphate dehydrogenase
Mechanism for the reaction catalyzed by thymidylate synthase
The thymine dimer photolyase: Structures of FADH- and FADH+ and the likely reaction pathway