Jay S. Skyler, MD, who has been testing an inhaled version of insulin for the past three years, says: "It's pretty simple. If you know how to breathe, which most people on this planet do, you can use it."
The inhalation device, which crushes a pellet of insulin into a fine cloud of powder that is then breathed deeply into the lungs, is one of several alternatives to insulin shots now being tested. These methods, which also include insulin pills and a spray inhaler, are not designed to replace the shots entirely, but to reduce the number of daily injections needed, researchers say.
Skyler, a diabetes expert from the University of Miami, says patients who have used the inhalation device tend to like it. After an earlier study of the device ended, 80% of the study participants with type 1 diabetes and 92% of those with type 2 diabetes continued to use it. Five longer-term studies, aimed at confirming its effectiveness and safety, are beginning. If approved by the FDA, the device could be available to patients as early as the end of next year.
The inhalation device consists of a flashlight-sized clear tube with a slot into which an insulin pellet is placed. Squeezing a trigger crushes the insulin. Placing your mouth over the chamber and taking one or two slow, deep breaths is enough to draw the powder into the lungs, where it is rapidly absorbed into the bloodstream.
Another approach now being tested involves a much smaller device that resembles an asthma inhaler. With this device, rather than going all the way to the lungs, the insulin spray coats the inside of the mouth and the back of the throat. Because it is easy for drugs to pass through the sensitive tissue there, the insulin can get into the bloodstream quickly.
The spray mimics the body's normal secretion of insulin and, like the inhaled insulin, appears to control blood sugar levels as well as frequent injections. Its manufacturer, Generex Biotechnology Corp., of Toronto, says the spray has essentially no side effects, and the only patient complaints have been about a slight medicinal taste immediately after using it.
Arthur Krosnick, MD, a researcher involved in early tests of the device, says patients tell him they like it because it's easy to use. "Time and again, they have said, 'If I had my druthers, I would rather have this device than a needle,'" he says.
Although it has only been tested in adults, Krosnick, a diabetologist and clinical associate professor at Robert Wood Johnson Medical School in Princeton, N.J., says the spray inhaler is simple enough that kids should be able to use it, if studies show it works as well for them.
The spray device has been tested in about 300 patients in the U.S. and other countries. In Canada, long-term trials -- the final step before drug approval -- recently began. The U.S. equivalent of those studies is expected to begin within the next two or three months, Krosnick says.
But a few hurdles must be cleared before the devices are approved for use. One potential problem is that, unlike injections that are precisely measured, inhaled doses may not be exactly the same each time people take them. Another concern is that taking particles deep into the lungs could cause breathing problems in some people, or lead to unhealthy changes in lung cells.
Skyler says some patients have been on the inhaled insulin for at least three years with no apparent lung problems. He adds that animal studies do not support the idea that insulin causes unhealthy cell changes in the lung. In human studies, testing of lung function has shown no changes among insulin inhalers, according to Inhale Therapeutic Systems, one of several companies that are developing inhaled insulin products.
Although an insulin pill might be easiest of all to use, insulin is currently only taken by injection. That's because it is a protein, which can be broken down in the stomach, like food, before it starts to work on blood sugar. Insulin injections get the drug into the bloodstream fast, and are typically taken before eating and before going to bed. The challenge for researchers has been to convert the insulin into a form that can be absorbed in a way that bypasses the stomach's acids.
Christopher Price tells WebMD that, unlike others who have tried to make pills that protect insulin molecules from degradation by stomach acid, his company, Protein Delivery Inc., of Research Triangle Park, N.C., is taking a different approach. By modifying the insulin's structure with substances that protect it from degradation, then encapsulating the resulting gel-like substance, researchers have been able to get insulin to the liver intact.
"This is important, not only because it mimics the pathway that insulin takes in a normal person, but it is the one thing that's missing from any other method of insulin delivery. They all go into the [bloodstream] first, and very little insulin, in a very delayed fashion, actually gets to the liver," Price says.
The pill is being tested at Georgetown Medical Center in Washington. Price says a viable version is not expected before 2005. Like the spray products, it is meant to be used before meals as a supplement to long-acting insulin.
Another promising advance involves an alternative to insulin itself. Investigators at Merck Research Laboratory are working with a compound derived from the leaf of an obscure fungus found in the Congo. In studies in animals, the fungus was found to mimic the effects of insulin.
- Researchers are developing new ways to deliver insulin for diabetics who require it every day. Such methods could reduce a patient's use of injections.
- Scientists are studying insulin inhalation devices and pills, and alternative, insulin-like medications.
- Patients seem to like the concept of fewer insulin injections, but researchers need to determine whether these new products are safe and effective to use over a lifetime.