As Exubera dives into murky waters, will it sink or swim?

The figure being thrown around for the market potential of a new non-injectable insulin product such as Exubera is as high as $1.5 bn (€1.3 bn) a year.

However, Vinayak Arora, analyst for market research firm >RocSearch​ India, believes that in the short-term, the impact of new inhaled insulin products on current devices in the market will not be significant.

"This is because many of the non-injectable insulins being developed have some inherent disadvantages, in particular increased costs and a loss in accuracy of the insulin dosage due to the external mode of delivery,"​ he told In-PharmaTechnologist.com.​

The extent of such limitations will determine each product's long-term chance of success.

>Pfizer's​ Exubera will be the first to go on sale in a few months time, however, it still has questions hanging over its long-term effect on lung function, and patients who use it will need to have their lungs tested regularly.

In addition, Exubera should not be used by patients who smoke, have chronic lung disease or a temporary impairment in lung function.

At this stage, Exubera and other similar devices in development are also limited to using regular short-acting insulin, so injections of long-acting insulin to provide around the clock coverage will usually still be needed.

Due to such factors, "Over the next few years at least, Exubera won't cause a replacement of needles, but a displacement,"​ said Leslie Williams, an inhalation technology expert and president & CEO of the specialist pulmonary inhalation technology company, >Ventaira.​

"I would expect that typically patients who currently take insulin injections 3-4 times per day may use Exubera to replace 1-2 of these injections,"​ said Williams.

Another major hurdle that products such as Exubera need to overcome before consumer uptake becomes widespread is the increased cost - expected to be at least double that of injectable insulin.

This cost increase is partly because Exubera is less effective than an injection at delivering a precise insulin dose, as only a small percentage the insulin that is inhaled actually reaches the bloodstream, so patients have to inhale a lot of insulin to get the amount their body needs, "wasting" a lot in the process.

A Cochrane review of six trials giving short-acting insulin by inhalation instead of injection highlights this, concluding that "the higher doses of inhaled insulin required may make it less cost-effective than injected insulin."​

In light of all these combined factors, "for the moment, Exubera will not replace injections of long-acting insulins for the majority of patients with Type 1 diabetes,"​ said Professor Simon Howell, Professor of Endocrine Physiology at King's College London and an expert on diabetes.

Dr Nancy Bohannon, who specialises in research in and treatment of diabetes in the US, believes instead that it will be particularly welcomed by Type 2 diabetics who are new to using insulin, and, having never had the experience of self-injecting before, are fearful of the idea.

Williams also agrees: "the availability of Exubera 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,"​ she said.

The evidence would also support this idea. In a recent Canadian study published in PharmacoEconomics​ journal, 99 per cent of participants with Type 2 diabetes using oral drugs preferred using inhaled insulin, compared with only 69 per cent of those with Type 1 diabetes already using injected insulin.

Similarly, diabetic patients who did not already use injected insulin said they were willing to pay $153 per month for inhaled insulin, compared to only $50 per month for those who were already insulin users.

However, Bohannon warned that while there may be an initial rush of people switching to Exubera when it first comes on the market, cost will be a major factor in the long-term continued use of the product.

"Patient uptake in the US will mainly depend on whether the government will provide any reimbursement for the new insulin products. For now, reimbursement is unlikely,"​ said Bohannon.

"However, when these products become cheaper and smaller, they have the potential to capture 20 per cent of the market,"​ she said.

Arora agrees: "As new and better device technologies reduce the cost and increase the convenience of insulin delivery, the existing devices will undergo a period of phase-out,"​ he said.

And when this occurs, companies involved in all aspects of traditional injectable insulin manufacturing will suffer, right across the spectrum, from manufacturers of syringes and pens, to sharps containers.