Sensitivity and reaction tested by administering the drug-

RUHS, Jaipur, PB B.Sc Nursing Entrance-2024

Pharmacology

Easy

Appeared in: RUHS, Jaipur, PB B.Sc Nursing Entrance-2024

Explanation

The intradermal route is the standard for sensitivity testing because the drug is injected into the dermis, which has a very limited blood supply.
This slow absorption rate minimizes the risk of a severe, systemic allergic reaction (anaphylaxis) and allows for a localized response.
Injecting into the dermis creates a visible bleb (wheal), making it easy to observe and measure the local reaction (redness and induration).
This method is used for common diagnostic procedures like the Mantoux test for tuberculosis and various allergy skin tests.

Option B: The intramuscular route is incorrect because muscles are highly vascular, leading to rapid absorption of the drug into the systemic circulation. This poses a significant risk of a severe, immediate allergic reaction.
Option C: The intravenous route is the most dangerous option for sensitivity testing. It delivers the drug directly into the bloodstream, causing an immediate systemic effect and potentially leading to life-threatening anaphylaxis if the patient is allergic.
Option D: The subcutaneous route involves injecting into the fatty tissue below the dermis. This tissue is more vascular than the dermis, resulting in faster absorption. While slower than IM or IV, it is not the preferred route for the localized, slow-release effect needed for sensitivity testing.

Clinical Relevance

Nursing practice connection: Knowing Routes of drug administration for sensitivity testing helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Using the correct intradermal technique is a critical patient safety measure to accurately assess for allergies while preventing potentially life-threatening anaphylactic reactions.
Nurses must always have emergency equipment, including epinephrine, oxygen, and resuscitation supplies, readily available when performing any type of sensitivity testing.
What if? If a bleb does not form during an attempted intradermal injection, it indicates the needle was likely inserted too deep into the subcutaneous tissue. The test is considered invalid and must be repeated at a new site, at least 2 inches away from the first attempt.

How to Approach the Question

First, identify the key concept in the question: the route for 'sensitivity and reaction testing'.
Recall the primary purpose of a sensitivity test, which is to observe a localized reaction to a substance in a controlled and safe manner.
Consider the different parenteral routes and their absorption rates: Intravenous (fastest) > Intramuscular > Subcutaneous > Intradermal (slowest).
Connect the purpose (safety and local observation) with the absorption rate. The slowest absorption route (intradermal) is the safest and most effective for this type of testing.
Eliminate the other options based on their faster absorption rates, which increase the risk of a systemic reaction.

Concept Tested & Keywords

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E6 Nelson Textbook of Pediatrics(2024) — Volume 1 pp. 1390-1392, 1470-1472

E6 Medicine Harrison 22e Part 1 p. 469-471