Inhaled Insulin

Inhaled Insulin

Inhaled Insulin

by Peter J. Nebergall, Ph.D.

From the Editor: The following article is

reprinted from the Fall, 1998, issue of the Voice of the Diabetic, a publication of the

Diabetes Action Network, a division of the National Federation of the Blind. Everyone

concerned about effective management of diabetes will be interested in what Dr. Nebergall

has to say:

Ever since insulin was first isolated in 1921,

folks have dreamed of a more attractive way to take it than by parenteral injection. Who

likes needles? Many alternatives to the syringe have been tried, but the successful ones

(the insulin pen, the insulin pump, needle-free air injection) still had to penetrate

below the skin to inject the dosage. Oral insulin (insulin pills) was tried but found

ineffective because the body's gastric juices destroyed the medication long before it

could be absorbed into the blood. Early attempts to inhale dry, powdered insulin worked

but proved impossible to moderate; administration produced quick absorption followed by

rapid fall-off.

The problem was to moderate the response of the

inhaled insulin, to make the dosage reproducible, so that adjustment of dose would be

possible. This has been accomplished. Not unlike timed-release oral medications, inhaled

insulins are encapsulated in soluble microcapsules to slow their rate of release. The

nature of the human lung dictates rigid size requirements for such

"microcapsules," and the problem has been to achieve these sizes reliably.

Several firms have been working to perfect this microencapsulation technology. Both

Andaris (from Nottingham, England) and Inhale Therapeutics (from California) have

succeeded in microencapsulating insulin.

Andaris states: "Preclinical testing is

currently underway." Inhale Therapeutics, working with pharmaceutical giant Pfizer,

has just completed phase two clinicals. Seventy subjects with type 1 diabetes and

fifty-one with type 2 were randomized into inhaled or conventional treatment regimes. A

related study of the reproducibility of inhaled dosage (through an inhaler device

developed by Inhale Therapeutics) was completely successful. "Inhaled insulin

administration was consistent from dose to dose, even with inexperienced users...pulmonary

dosing is as consistent as injection."The results of these two three-month trials

were made public at the American Diabetes Association's fifty-eighth annual scientific

sessions in Chicago, Illinois, June 16, 1998. Researchers reported that, when inhaled

insulin was used as a replacement for quick-acting, mealtime-injected insulin (with

longer-acting basal insulin still injected), the degree of control was approximately

equal, with the added benefit of increased patient compliance.

Questions:

* Is inhaled insulin available now? No. Phase 3

clinicals are scheduled to start in November. Estimates are that the new insulin may be on

the market in three to five years.

* Is it a total substitute for injected insulin?

No, current inhalable formulations are designed to cover mealtime needs; basal insulin

would still be injected. This may well change.

* Is it tight control? Not yet. At this time

researchers compare it favorably to one injection of long-acting insulin taken in the

morning. Expect this to improve.

* Is this the wave of the future? Very possibly.

Both Inhale Therapeutics and Andaris report progress on a dozen or more different

inhalable medications. With luck we may not need the syringe too much longer.