Insulin lispro acts within 15 minutes of subcutaneous injection because of a specific structural modification. That modification is:

• A Substitution of proline at position B28 with aspartic acid
• B Acylation of lysine B29 with a myristic acid side chain
• C Addition of two arginine residues at the C-terminus of the B chain
• D Reversal of the sequence of amino acids at positions B28 and B29 ✓

Explanation

Lispro is produced by swapping lysine D29 and proline D28 (the reverse of native human insulin), which destabilises self-association into hexamers and allows faster absorption. Option A describes insulin aspart, option C describes insulin glargine, and option B describes insulin detemir. Recognising which structural change belongs to which analogue is a frequently tested discriminator.

Reference: Katzung Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.