Regarding insulin pharmacokinetics: A patient takes 0.5 units/kg of insulin glargine (body weight 70 kg). The volume of distribution is approximately 0.15 L/kg. Calculate the expected plasma drug amount distributed at steady state. (Note: This question tests Vd conceptually; select the statement about insulin glargine PK that is most accurate.)
- A Insulin glargine has a peak at 2–4 hours and duration of 12–16 hours
- B Insulin glargine forms microprecipitates at the injection site (pH 4 formulation), providing slow release with no pronounced peak and duration of 20–24 hours ✓
- C Insulin glargine is an intermediate-acting insulin similar to NPH, with duration of 14–16 hours
- D Insulin glargine has a half-life of 2 hours and must be given twice daily
Correct answer: B. Insulin glargine forms microprecipitates at the injection site (pH 4 formulation), providing slow release with no pronounced peak and duration of 20–24 hours
Explanation
Insulin glargine is formulated at pH 4 (acidic), causing it to be soluble in the vial. After subcutaneous injection into physiological pH, it forms microprecipitates that dissolve slowly over 20–24 hours, producing a flat, peakless absorption profile—making it ideal as a once-daily basal insulin. NPH insulin is intermediate-acting with a peak (not glargine). The peakless profile means lower nocturnal hypoglycaemia risk compared to NPH.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.