PRODUCTION OF LONG ACTING INSULIN PREPARATIONS

A stable insulin preparation having a lasting action and having low antigenicity is prepared by reaction of acidic groups of the insulin with basic groups of organic compounds. The reaction is carried out in an aqueous buffer solution which contains a protein-dissociating or protein-depolymerising agent. Basic polypeptides, e.g. protamines, or cleavage products of basic polypeptides are preferred as organic compounds containing a basic group. The protein-dissociating or protein-depolymerising agent is preferably urea.