Safety of intranasal human insulin: A review

ubheadings – aims The nasal application of human insulin is frequently used for investigating brain insulin action. It is utilized in studies on the physiological role of insulin in the human brain as well as in therapeutic interventional trials and its effects have been investigated after both acute and long-term administration. This review aimed to assess the safety of intranasal human insulin in human studies and the temporal stability of nasal insulin sprays. Material and Methods The electronic search was performed using MEDLINE. We selected original research on intranasal human insulin without further additives in humans. The studies included could be of any design as long as they used human intranasal insulin as their study product. All outcomes and adverse side effects were excerpted. Results Thirty-eight studies on 1092 persons with acute application and 18 studies on 832 persons with treatment lasting between 21 days and 9.7 years were identified. No cases of symptomatic hypoglycemia or severe adverse events were reported. Transient local side effects in the nasal area were frequently experienced after intranasal insulin and placebo spray, while other adverse events were less commonly reported. There are no reports of subjects who were excluded due to adverse events. No instances of temporal stability of nasal insulin were reported in the literature. Tests on insulin that had been repacked into spray flasks revealed that it had a chemical stability of up to 57 days. Conclusions Our retrospective review of published studies on intranasal insulin did not reveal any safety concerns. There is, however, insufficient data to ensure long-term safety of this modality of chronic insulin administration. Improved insulin preparations that cause less nasal irritation would be desirable for future treatment.