Pharm 101: Insulin

Class

Endogenous hormone


Mechanism of action
  • Acts on ligand-regulated tyrosine kinase receptor
  • Promotes uptake of glucose from blood into tissues, especially fat, liver, skeletal muscle
  • Promotes glycogen synthesis

Formulations
  • IV or SC administration
  • Rapid and short acting:
    • Clear solution, neutral pH
    • Rapid onset, short duration
    • e.g. insulin lispro
    • Short-acting regular soluble insulin is used for IV infusion, as it immediately dissociates on dilution and thus is able to be more precisely delivered
  • Intermediate acting:
    • Turbid solution, neutral pH
    • Protamine in phosphate buffer (NPH) to prolong action
    • e.g. insulin aspart protamine
  • Long-acting:
    • Clear solution
    • Slow onset, prolonged action
    • Daily administration mimics basal insulin secretion
    • e.g. insulin glargine

Clinical uses
  • Regulation of blood glucose:
    • Combinations of insulins with different durations of actions (see below) aim to replace basal insulin requirement (50%) and meal requirement (50%) to achieve optimal glycaemic control
  • Hyperkalaemia
  • Calcium channel blocker overdose

Adverse effects
  • Hypoglycaemia
  • Hypoglycaemia unawareness
  • Allergy (usually due to non-insulin contaminants)
  • Immune insulin resistance
  • Lipodystrophy at injection sites

References

Pharm 101 700

Pharmacology 101

Top 200 drugs

MBBS (UWA) CCPU Emergency Medicine Trainee with interests in medical education, ECG interpretation, and the use of point-of-care ultrasound in the undifferentiated patient. Co-author of the LITFL ECG Library | Twitter

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