New Forms of Insulin

Abstract

This paper reviews some recent developments in insulin purification and formulation. Neutral Regular insulin (unbuffered Regular insulin with pH adjusted to neutrality, designated NRI) maintained nearly full potency when stored at room temperature for twelve months, while the potency of acid Regular (“commercial”) insulin (ARI) had dropped 20 per cent. When NRI and ARI were administered in combination with NPH or Ultralente insulin, comparable time activity responses were elicited. In fasted normal subjects subcutaneous doses of NRI and ARI gave similar blood glucose responses. Thirty-seven patients with allergy to commercially available insulin were treated with one or both of two highly purified insulins (single peak and single component pork insulin). Improvement occurred in 78 per cent. Single component insulin was usually, but not always, superior to single peak insulin when both were tested in the same patient. Insulin was administered orally with an absorption promoter, Brij 98, to twenty normal and thirteen diabetic fasted subjects in crossover studies. Under optimum conditions, definite responses were observed in about 50 per cent of subjects. Serum insulin measurements in the normals and diabetics revealed that increased concentrations were not necessarily associated with falls in blood glucose concentrations in spite of delivery of the insulin by the portal route. Because of the amounts of insulin required, the limitations of test conditions, and a high incidence of nausea, this project has been discontinued.