Toward a needle-free insulin
More than 70 years after insulin was found to be a treatment for diabetes, doctors still are trying to figure out a better way to get the hormone into the bodies of people who need it -- one that doesn’t require needle sticks several times a day.
Finally, non-injectable insulin appears within reach. An inhaled form may be available within a year or two, and an even bigger improvement -- an insulin capsule or tablet -- could be on pharmacy shelves within five years.
“It’s not a natural thing to give oneself a shot multiple times a day,” says Dr. Stephen Clement, an endocrinologist at Georgetown University Medical Center in Washington, D.C. “Oral insulin would really enhance a patient’s quality of life.”
Normally secreted by the pancreas, insulin helps remove glucose from the bloodstream. In Type 1 diabetes, the pancreas fails to release enough insulin for glucose removal, necessitating daily injections. In Type 2 diabetes, the pancreas produces insulin but the body fails to use it properly. Type 2 diabetes often can be controlled with diet and other medications, but sometimes insulin is necessary. But insulin injections aren’t a cure. The disease is difficult to control, putting patients at risk for complications. Their diet must be carefully monitored to regulate the consumption of carbohydrates, proteins and fats, and insulin shots must be timed so that blood levels remain stable.
One option to help diabetics better control their glucose and avoid needles is inhaled insulin. Pfizer Inc. and Aventis have applied to market their inhaled insulin, called Exubera, in Europe and are in discussions with the Food and Drug Administration for sales here.
Exubera, a dry powder, is inhaled into the lungs before eating. Needles aren’t needed, and the drug is quickly absorbed into the bloodstream.
“This will be a good step,” Clement says. “A good percentage of the insulin gets into the bloodstream, and it does control blood sugar.”
An insulin pill, however, is the ultimate goal of many researchers. They believe that it would most closely duplicate the natural release of insulin and would best control glucose.
In healthy people, the liver is the first and most important target for insulin secreted by the pancreas. The liver then releases the insulin into the bloodstream. But when injected (or inhaled), insulin pours into the bloodstream, stimulating the muscle and fat cells to control blood glucose and leaving the liver with a smaller role to play.
Getting insulin past the gut to the liver is key to a successful insulin pill, Clement says. “The entire gastrointestinal tract is set up to digest proteins. It’s like a minefield the whole way through. A number of companies have been trying to find a way to protect the insulin molecule to bypass these enzymes.”
Two companies recently announced small studies showing that an insulin pill was safe and appeared to control hyperglycemia, a rise in glucose levels after eating, that can occur with injected insulin.
One company, Nobex, published a study in the January issue of the journal Metabolism on a form of oral insulin that was modified so that it wouldn’t be completely digested by stomach enzymes. The other company, Emisphere, recently announced data on an insulin tablet that is surrounded by a synthetic chemical compound to keep the molecule from being destroyed in the gut. That study has not been published.
“In terms of convenience, if an insulin pill could be designed, that would be best,” says Dr. Nathaniel Clark, national vice president for clinical affairs for the American Diabetes Assn. “Inhaled insulin is a very cumbersome process; you have to carry around a special device.”
Furthermore, doctors might find it easier to persuade some patients -- such as those with Type 2 diabetes who have not succeeded with other treatments -- to take insulin if an alternative to shots was available. “Whether founded or not, people have a tremendous fear of injections,” Clark says.
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Complications of diabetes
People with diabetes are at a higher risk for developing other health problems, including heart disease, kidney disease, eye problems, nerve damage and skin disorders.
Almost all of these complications are caused by having too much glucose in the blood. When blood sugar is too high, the small blood vessels that carry blood through the body get clogged, and blood flow is impeded. Studies show that people who keep their glucose under tight control have half as many problems with complications.
Source: American Diabetes Assn.
