All of the following insulin structures are clearly visible except

Appeared in: DSSSB 12 August 2024

Explanation

The question asks to identify the insulin that is not clear, meaning it has a cloudy appearance.
NPH (Neutral Protamine Hagedorn) is an intermediate-acting insulin that is formulated as a suspension with protamine.
The presence of protamine gives NPH insulin its characteristic cloudy or milky appearance.
Unlike other insulins, NPH must be gently rolled or inverted to resuspend the particles before administration.

Option A: Regular insulin is a short-acting insulin that is a clear, colorless solution.
Option C: Glargine and Detemir are long-acting basal insulins. Both are manufactured as clear, colorless solutions.
Option D: Rapid-acting insulins, such as lispro, aspart, and glulisine, are all clear, colorless solutions.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Physical appearance of insulin preparations as background academic context rather than a clinical decision trigger.
Patient safety is paramount in insulin administration. Nurses must always inspect insulin vials before drawing up a dose. A clear insulin that appears cloudy or a cloudy insulin that has clumps or frosting should be discarded.
The mnemonic 'Clear before Cloudy' is a critical safety check when mixing insulins (e.g., Regular and NPH). Drawing the clear insulin first prevents contamination of the clear vial with the protamine from the NPH, which would alter its onset and action.
What if a patient needs to mix Regular and NPH insulin? The nurse must first inject air into the NPH (cloudy) vial, then inject air into the Regular (clear) vial, draw up the Regular insulin, and finally draw up the NPH insulin into the same syringe.

How to Approach the Question

First, analyze the question stem and identify the keywords. The keywords here are 'insulin', 'clearly visible', and the negative lead-in 'except'.
The term 'except' indicates that you need to find the option that does not fit with the others. 'Clearly visible' implies a clear solution.
Therefore, the question is asking you to identify which insulin type is NOT a clear solution (i.e., it is cloudy).
Recall the physical properties of different insulin types: Rapid-acting, Short-acting (Regular), and Long-acting (Glargine, Detemir) are clear.
Remember that Intermediate-acting insulin (NPH) is a suspension and has a cloudy appearance.
Based on this knowledge, select NPH as the correct answer because it is the exception.

Concept Tested & Keywords

Concept Tested: Physical appearance of insulin preparations
Stem keywords: insulin, clearly visible, except
Lead-in keywords: except
Negative lead-in flag: The question asks for the exception among the given options.

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E6 Pharmacology Katzung 16e p. 1177-1179

E6 Medicine Harrison 22e Part 2 p. 1114-1116

Practise the full DSSSB 12 August 2024

Attempt every question from this paper in a timed mock, then review the full solution for each one.