Clinical pharmacologic studies with human insulin (recombinant DNA).

Normal fasting subjects were used to study the pharmacokinetics of human insulin (recombinant DNA). Purified pork insulin (PPI) was used as a control agent. There was no difference in serum concentrations between neutral regular human insulin and PPI after intravenous administration. When given subcutaneously, peak concentrations are occasionally higher for human insulin than for PPI. The bioavailability indices for the two insulins are essentially the same. NPH human insulin produced a slightly higher serum concentration after 4 h than did NPH PPI. Studies with 70/30 NPH-regular mixtures suggest that the affinity of protamine for human insulin is less than that for PPI. The serum insulin concentrations after lente human insulin and PPI were not different. These studies, and a review of the published clinical pharmacologic literature, indicate that when present the differences between human insulin and PPI are minimal.