Insulin detemir has a longer and more predictable duration of action than NPH insulin primarily because it:

• A Is acylated with myristic acid, promoting reversible binding to serum albumin ✓
• B Forms multi-hexamer dihexamers after zinc-mediated self-association
• C Precipitates at the neutral pH of subcutaneous tissue
• D Is conjugated to polyethylene glycol, slowing renal clearance

Explanation

Detemir has a myristoyl fatty acid attached to lysine A29. This allows reversible albumin binding both in the vial and in plasma, producing slow, reproducible release and an action profile of about 20 hours with low variability. Option B describes degludec, whose phenol-mediated multi-hexamer chains form a depot. Option C describes glargine, which precipitates because its acidic formulation is neutralized in tissue. Pegylation is not used in any marketed insulin.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.