A 24-year-old man presents with diabetic ketoacidosis, blood glucose 480 mg/dL, pH 7.12. Intravenous insulin is ordered. Which insulin preparation is appropriate for intravenous administration?
- A Insulin glargine
- B Neutral protamine Hagedorn (NPH) insulin
- C Regular insulin ✓
- D Insulin detemir
Correct answer: C. Regular insulin
Explanation
Only regular insulin may be given intravenously. It is a clear solution without protamine or zinc additives that alter distribution, so it acts predictably when infused, with an onset of minutes and a half-life of about 5 to 8 minutes by this route. Glargine, detemir and NPH are all designed as subcutaneous depot preparations; their precipitated or protein-bound formulations make intravenous kinetics erratic and they are never used for DKA infusion.
Reference: Katzung's Basic and Clinical Pharmacology, 16th ed.
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