Insulin analogues: an example of applied medical science.
Insulin analogues were developed to try and achieve more physiological insulin replacement from injection in the subcutaneous site. Their pharmacokinetics and pharmacodynamics differ from human insulin when injected subcutaneously because of alterations in the amino acid sequence of the insulin molecule. The rapid-acting insulin analogues, lispro, aspart and glulisine, have a rapid onset of action and shorter duration of action because of changes to the B26-30 portion of insulin inhibiting formation of dimers and hexamers. They appear to improve postprandial glucose, incidence of hypoglycaemia and patient satisfaction and, when used in combination with basal insulin analogues, improve glycosylated haemoglobin in comparison to conventional insulin therapy. Additionally, they have been successfully used in children, pregnant women, in pump therapy and as part of premixed biphasic regimens. The two basal insulin analogues, glargine and detemir, developed by adjusting the isoelectric point and adding a fatty acid residue, respectively, have a protracted duration of action and a relatively smooth profile. Their pharmacokinetic and pharmacodynamic profiles have been assessed using euglycaemic clamp protocols. Both analogues have a longer duration of action, less of a peak of activity and a reduced variability with repeated injection. There is some evidence to suggest that detemir may have a slight hepatoselective effect. Clinical studies have shown a lower relative risk of hypoglycaemia and detemir appears to have a weight-sparing action. Insulin analogues represent a successful example of applied medical science.