Pfizer spokesman Rick Chambers downplayed concerns over any potential pulmonary safety risks for diabetics using Exubera inhaled insulin, telling the Tribune-Star in Terre-Haute, Indiana that aging affects a person’s lung capacity every year:

“After you turn age 25, you naturally lose about 1 percent of your lung capacity annually as you age,” Chambers said. “[Using Exubera] is a one-time decrease that reverses if the therapy is stopped.”

The FDA reportedly delayed Exubera approval for several years because of concerns about pulmonary risks and harm to diabetics’ lungs.

In another new report on anticipated Pfizer losses stemming from the expiration of  the company’s patents for the antidepressant Zoloft, blood-pressure drug Norvasc, and allergy medicine Zyrtec, CNN.com reports that Pfizer “has been cutting jobs and closing plants, and aims to save $4 billion through its cost-cutting.” At the same time, Pfizer:

“is also looking forward to getting its recently-approved insulin inhaler Exubera on the market, with analysts calling the drug a potential blockbuster.”

A new report from Toronto’s Globe and Mail contends that Pfizer and other pharmaceutical companies are facing an onslaught in Canada from stiff competition by generic drug manufacturers.

This conclusion is based on a study done by IMS Health, a provider of market intelligence to companies in the pharmaceutical and health-care industries:

“Although the retail pharmacy sector posted a respectable growth in 2005,” says Ian Therriault, IMS Health’s senior industry expert, “the slower growth has been caused by new competition faced by several brand-name drugs facing generic competitors, additional cost-containment measures put in place by governments, fewer top-selling products being introduced and lingering safety concerns around some of Canada’s most prescribed classes.”

Generics slowely chipped away at Pfizer’s $55M of Zithromax sales in 2005, accounting for $1.28M in the last two months of the year.

The effect that diabetes has on Canada’s population seems likely to provide a growth market for Exubera and other inhaled insulin products — if they receive approval from Health Canada, the government agency with regulatory oversight for the country’s health care. In late January 2006, Exubera was approved by the FDA and EU, becoming the first inhaled insulin to secure regulatory approval anywhere in the world.

The IMS study found that in 2005, “[d]iabetes therapy recorded the second-fastest growth rate among Canada’s leading prescribed classes with prescriptions up 8% over 2004.”

Potential mitigating factors to balance any continued drop in brand name drug sales due to generic competition include Exubera, according to Ian Therriault, IMS Health’s senior industry expert.

A 2001 paper delivered by Dr. William T. Cefalu, an American doctor at, at the Canadian Society of Endocrinology and Metabolism’s Conference in Edmonton Alberta, explored the feasibility of noninvsaive insulin delivery systems. Cefalu listed six inhaled insulin drugs in development at the time:

Product Manufacturer
Aerdose Aerogen
AERx Aeradigm Corporation
AIR Alkermes, Inc.
Exubera Nektar Therapeutics (which worked with Pfizer and Sanofi-Aventis)
Spiros Elan Pharmaceuticals, Inc.
Technosphere
Insulin Pharmaceutical Discovery Corp.

Cefalu concluded his paper with a single paragraph on the potential risks of inhaled insulin:

“The efficacy and safety of inhaled insulin in patients with chronic obstructive pulmonary disease (COPD) or emphysema, or in chronic smokers, has not been determined in the studies discussed above. Evaluation of pulmonary function over the long term is ongoing.”

As we’ve seen now, the potential pulmonary risks and safety issues associated with inhaled insulin like Exubera can be serious. Will this affect the potential for Exubera’s approval in Canada, and possibly slow widespread usage by diabetics there? These questions do not currently appear to have answers.

Given the known and unknown risks of Exubera inhaled insulin for diabetics, a report from NPR says that “[t]he FDA has asked the manufacturer, Pfizer, to study the drug’s long term effects in 5,000 patients.”

Another drug delivery company, MannKind Corp.,  is fast on the heels of Pfizer and Nektar Therapeutics inhaled insulin approval for Exubera.

California-based MannKind Corp. just announced that it was proceeding with two different 12-month long Phase 3 clinical trials with the inhaled insulin that it is working on, Technosphere Insulin (’TI’).

The first trial will include 500 insulin-dependent Type 1 diabetics.  The second trial involves 500 Type 2 diabetics.

The company’s Chief Scientific Officer, Peter Richardson, said that MannKind’s

…prior studies have shown improved glycemic control in a dose-dependent manner as measured by decreases in HbA1c levels, and by significant reductions in glucose excursions following a meal.

Without going into any written details, Richardson told investment analysts that the MannKind remains “confident that these two new studies will further confirm the safety and efficacy that we have seen to date.”  An audio webcast of the company’s announcement, with other information, will be available for roughly two weeks.

If Phase 3 trials conclude with positive results, Exubera may have a competitor chasing the anticipated billion-dollar market for inhaled insuling products.