Question

A 70-years-old man was administered penicillin intravenously. Within 5 minutes, he developed generalized urticaria, swelling of lips, hypotension and bronchospasm. The first choice of treatment is to administer:

• A. Chlorpheniramine injection
• B. Epinephrine injection
• C. High-dose hydrocortisone tablet
• D. Nebulized salbutamol

Hint:

In anaphylaxis with hypotension and bronchospasm, only one drug acts on the airway, blood pressure and mediator release together.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
An elderly man develops generalized urticaria, lip swelling, low blood pressure and wheeze within minutes of getting intravenous penicillin. This is anaphylaxis, and we need the first drug to give.

Step 2: Key Concept:
Anaphylaxis is a rapid, severe, multi-system allergic reaction (skin, airway and circulation together) driven by a sudden release of histamine and other mediators from mast cells. Epinephrine (adrenaline) is the only drug that acts on all the arms of this reaction at once, since it constricts blood vessels to raise blood pressure, relaxes the airway muscle to relieve bronchospasm, and cuts down further mediator release from mast cells.

Step 3: Detailed Explanation:
Chlorpheniramine (an antihistamine) helps the skin symptoms like urticaria and itching but works slowly and does nothing for the low blood pressure or the airway narrowing, so it cannot be the first drug in a reaction with hypotension and bronchospasm. Hydrocortisone works over hours, not minutes, and would not reverse the immediate drop in blood pressure or airway spasm, so it is used as a second-line agent to prevent a delayed or biphasic reaction, and a tablet form would also be far too slow to absorb in a hypotensive patient. Nebulized salbutamol treats bronchospasm alone but does not correct hypotension or the airway edema causing lip swelling, so it is only an add-on treatment, not the first choice. Epinephrine given promptly, usually into the muscle of the outer thigh, is the only agent that reverses the hypotension, bronchospasm and further mediator release together, and delay in giving it is the main reason anaphylaxis becomes fatal.

Step 4: Final Answer:
The first choice of treatment in this anaphylactic reaction is epinephrine injection, option (2).