At present, >Pfizer is running a lone race, having gained a head start in this new market, predicted to generate as much as $1.5 bn (€1.2 bn) a year, until new competitors begin to emerge over the next few years.
Exubera, developed in partnership with >Nektar Therapeutics, was finally approved last week by both the US Food and Drug Administration (FDA) and the European Commission, for the treatment of adults with Type 1 and Type 2 diabetes, after a number of hold-ups over lung-safety concerns.
The news is big for biotech company Nektar, which has flourished through its partnership with Pfizer, and will now provide support in the manufacturing processes which are now beginning for Exubera insulin and the inhalation devices, as well as receiving royalties on all marketed products.
Pfizer is responsible for the clinical development, marketing and manufacturing of Exubera insulin, and has invested in two manufacturing facilities dedicated to the purpose: one of the world's largest insulin plants in Frankfurt, Germany, where the base insulin will be made, and a highly automated production plant in Terre Haute, Indiana.
The base insulin will be shipped from Frankfurt, to either Pfizer's plant in Indiana or Nektar's plant in San Carlos, California, where it will be reformulated into an inhalable powder using Nektar's proprietary formulation process, and then packaged into blister packs. The insulin will then be assembled into the drug delivery devices at Pfizer's Indiana facility.
Manufacturing of the delivery devices has been outsourced by Nektar to two contract manufacturing organisations, Bespack in the UK and West (formerly TechGroup) in Arizona, US.
In patients with Type 2 diabetes, Exubera can be used alone as an alternative to rapid-acting insulin injections or diabetes pills, or, where required, in combination with diabetes pills or longer-acting insulin.
In patients with Type 1 diabetes, Exubera will only be used in combination with longer-acting insulin, due to the nature of the disease.
However a considerable subset of diabetic patients are immediately ruled out from benefiting from the treatment.
Patients should not take Exubera if they smoke or have stopped smoking less than six months before, and the product is not recommended for people that have chronic lung disease (such as asthma, chronic obstructive pulmonary disease or emphysema). Also, Exubera should not be used at all by people with unstable or poorly controlled lung disease.
Leslie Williams, an inhalation technology expert and president & CEO of the specialist pulmonary inhalation technology company, Ventaira, also pointed out that "there will be other occasions when a person's lung function may become acutely compromised, for example pneumonia, and they will be temporarily unable to use the product."
In addition, Exubera may affect lung function so patients will need to have their lungs tested by their doctor both before starting Exubera and at regular intervals thereafter.
With the regulatory hurdle now positively cleared, attention is focusing on the commercial prospects of Exubera, which has a potential market of millions of patients.
Some market analysts predict it will be a blockbuster, while others believe it has been overvalued. At this stage, however, many industry experts believe that to hazard a guess at the uptake of the product would be purely speculative and it seems that only time will tell.
"From a quality of life perspective, Exubera is a great thing. In our gadget-driven society, the availability of this product is a tremendous advantage for the right subset of patients. Rapidly growing numbers of young diabetic patients, along with those who have not yet become accustomed to using needles will be particularly receptive," Williams told In-PharmaTechnologist.com.
"However, over the next few years at least, it won't cause a replacement of needles, but a displacement. I expect that typically patients who currently take insulin injections 3-4 times per day may use Exubera to replace 1-2 of these injections," she said.
Commenting on the product, Professor Simon Howell, Professor of Endocrine Physiology at King's College London and an expert on diabetes, told In-PharmaTechnologist.com: "This is certainly a good step forward in that it shows conclusively that insulin can be delivered effectively by this [pulmonary] route."
"However, for the moment this product will not replace injections of long-acting insulins for the majority of patients with Type 1 diabetes," he said.
Exubera is inhaled into the lungs orally before meals using a hand-held inhaler that does not require batteries or electricity.
The inhaler, which weighs four ounces and is about the size of a carrying case for a pair of eyeglasses, is designed to deliver an accurate and precise dose of insulin each time it is used.
The two giants that currently dominate the insulin market, Eli Lilly and Novo Nordisk are also developing their own inhailable insulin products but are probably years behind Exubera in getting approval.
As the first company to get such a product onto the world stage, the industry's eyes will now be glued on watching Exubera's uptake and performance, and Pfizer will need to follow through with post-marketing studies of the product, particularly as population groups begin to expand beyond those included in the initial trials.