Inhaled insulin approved as diabetes treatment option

Washington -- Physicians welcomed the Food and Drug Administration's approval Jan. 27 of inhaled insulin, particularly for those patients with poor glycemic control who are unwilling to accept several daily insulin injections.

However, the inhaled insulin, which will be marketed as Exubera, isn't for everyone. It was approved only for those older than 18 and should not be prescribed for current smokers, for those who have smoked in the last six months or for patients with underlying lung disease.

Its long-term pulmonary effects are unclear. The drug's manufacturer, Pfizer, is continuing to follow 5,000 patients on Exubera over the next five years to see whether they experience any significant decrease in lung function over time. Minor decreases were seen among some of the patients in the clinical trial.

Nevertheless, a large portion of the 5 million people who use insulin may be able to switch at least some of their injections to a puff, or several puffs, from an inhaler. Exubera is being hailed as the first new delivery option since the discovery of insulin in the 1920s.

Diabetes affects nearly 21 million Americans, or 7% of the population, and another 41 million people are thought to have pre-diabetes, which increases the risk of developing type 2 diabetes, according to the Centers for Disease Control and Prevention.

Exubera is a fast-acting insulin that reaches peak concentration more quickly than some injectable insulin. It should be taken 10 minutes before meals, according to Pfizer.

In type 1 diabetes, Exubera may be added to daily injections of longer-acting insulin as a replacement for short-acting insulin taken with meals. In type 2 diabetes, inhaled insulin may be used alone, with oral pills or with longer-acting insulin.

Risk-benefit ratio

The decision about using the new drug depends very much on the patient. "For a person whose blood sugar level is quite high and does not take insulin but needs insulin, the benefit would be dramatic," noted Robert Rizza, MD, president of the American Diabetes Assn.

"On the other hand, for an individual whose blood sugars are very wellcontrolled, then even a small risk may be unacceptable, because the benefit would be small."

Dr. Rizza has served as an adviser for Pfizer but was not an investigator on Exubera trials.

Although Richard Jackson, MD, senior physician and investigator at the Joslin Diabetes Center in Boston, is pleased to have more treatment choices to offer patients, he questions just how many will find the new product useful.

For one thing, he said, patients' fear of needles may be overblown. "The new needles are very small and sharp. Over 95% of people don't feel the injection at all."

The real problem with taking insulin is not the injections but the need to vary the dose, he said. "You need to think about what you are eating, check your blood sugar before and after meals, and if you are thinking of exercising, you have to bring that into the equation." None of that will change with inhaled insulin.

And since Exubera will be available only in 1 mg and 3 mg doses of powder packed in blister capsules, there will be less ability to vary the dose than there is with injectable insulin, noted Dr. Jackson.

Long-term effects unknown

Patients will also be asking physicians about the long-term effects of Exubera. But there is no answer as yet. It was studied in about 2,500 adult patients with type 1 and type 2 diabetes for an average of 20 months before approval.

For now, physicians would have to respond that the long-term effects are unknown, but "we will follow your pulmonary function carefully," said Dr. Jackson.

The FDA recommends that patients have baseline tests for lung function after the first six months of treatment with inhaled insulin and every year thereafter, even if there are no pulmonary symptoms. The tests can be done with a handheld spirometer, said Robert Meyers, MD, director of the FDA's Office of Drug Evaluation.

Exubera is expected to be available by midyear, and Pfizer reports it will be priced competitively.