Rapid onset of action of insulin lispro compared with regular human insulin is explained by which structural modification?

• A Addition of a myristic acid chain to the B chain
• B Substitution of proline at position B28 with lysine and lysine at B29 with proline
• C Deletion of the terminal threonine at position B30
• D Reversal of amino acids at positions B28 and B29 ✓

Explanation

Lispro reverses the order of proline B28 and lysine B29 on the insulin B chain. This disrupts the hydrophobic interactions needed for hexamer formation and self-association, so the injected insulin remains largely dimeric and monomeric and is absorbed within 15 minutes. Option B describes the modification of insulin aspart? No, option B actually describes swapping both residues, whereas aspart replaces proline B28 with aspartic acid. Option A describes detemir, and deletion of B30 threonine characterises insulin degludec.

Reference: Katzung's Basic and Clinical Pharmacology, 16th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.