With the date of the final approval for an inhaled insulin product appearing to draw closer, a talk at the latest European Association for the Study of Diabetes' meeting in Athens has outlined the drawbacks of this particular method of insulin administration. While the FDA advisory committee ruled in favor of inhaled insulin, there are still a number of concerns that remain unaddressed.
Inhaled insulin promises that, in terms of efficacy, it can be interchangeable with most prandial insulins, while at the same time offering greater patient satisfaction and convenience, which, in turn, could lead to increased patient compliance and improved outcomes.
However, critics insist that there are still unresolved issues with inhaled insulin. Some say the proposed convenience advantage might remain largely theoretical, but the overriding concern is the safety profile of inhaled insulin. While clinical trials have demonstrated a slight "non-progressive" decrease in pulmonary function, there are those who maintain that pulmonary function might still be affected in the long-term.
Another issue is the development of insulin antibodies, possibly driven by the fact that up to 10 times the equivalent amount of subcutaneous insulin needs to be delivered in the lung to achieve a similar effect. Concerns over the action of insulin as a growth factor have been expressed. Lipoproliferation in the injection site has been noted after chronic subcutaneous insulin use. This issue may be circumvented by periodically changing the injection site. However, if lipoproliferation in the lung proves to be an issue with inhaled insulin, there is no easy way to evade it and it could lead to severely compromised lung function.
In addition, the packaging of the dry insulin powder used in inhaled insulin, namely blisters containing either one or three units of insulin, might lead to dosing inflexibility and complexity, thus negating the proposed compliance advantage. The latter will also be affected by the sheer size and complexity of the currently available devices.
Datamonitor believes that although inhaled insulin has the potential to become a blockbuster drug, the issues outlined above, in combination with the fact that it is expected to command a price premium without offering any improvement in efficacy, are cause for concern and might seriously impact upon its commercial success.