A nurse is caring for a client who experiences anaphylactic shock in response to the administration of penicillin. Which of the following medications should the nurse administer first?

A. Albuterol is incorrect because, although it can relieve bronchospasm, it does not address the life-threatening hypotension, airway edema, and vasodilation caused by anaphylaxis. B. Epinephrine is correct because it is the first-line, life-saving treatment. It rapidly constricts blood vessels to raise blood pressure, relaxes bronchial smooth muscle to improve airflow, and reduces mucosal edema in the airway. Immediate intramuscular injection in the mid-outer thigh is recommended, and delaying epinephrine increases the risk of cardiovascular and respiratory collapse. C. Hydrocortisone sodium succinate is incorrect because corticosteroids have a delayed onset of action. They are used to prevent prolonged or biphasic reactions but do not immediately reverse airway obstruction or hypotension. D. Diphenhydramine is incorrect because antihistamines primarily relieve itching, hives, and mild allergic symptoms. They do not reverse hypotension or airway constriction and should be administered after epinephrine.