Posted: 7:05 p.m. Thursday, April 11, 2013
April 11, 2013 -- A new oral diabetes drug is expected to arrive on pharmacy shelves in the U.S. this week.
Many people predict that Invokana (canagliflozin), approved by the FDA in March, will be a brisk seller. That's partly because it treats type 2 diabetes in a new way.
Losing weight can help people control their diabetes.
In one 26-week study, those on Invokana lost about 6 to 8 pounds, while those in the placebo group lost only about a pound.
But the drug has side effects, including infections of the urinary tract, penis, and vagina. This leads some experts to have less enthusiasm for the new medicine.
It will also cost a lot more than other diabetes drugs. The wholesale cost for Invokana is $8.77 a pill, according to Katie Mahony, a spokeswoman for Janssen. Retail cost for the 100-milligram starting dose, without co-pays or coverage, is about $10 a pill, or $300 a month.
The popular diabetes drug metformin can cost as little as 25 cents a pill.
"It's another way to control diabetes without injections," says Anthony McCall, MD. He is the James M. Moss Professor of Medicine at the University of Virginia School of Medicine in Charlottesville. He was not involved in the development of the new drug.
A new pill is welcome, McCall says, for some of the estimated 24 million Americans with type 2 diabetes, especially as an alternative to injecting insulin.
"People do have strong feelings about injectable medications," he says. However, he and other experts say they don't expect Invokana to replace other drugs, but rather to offer another option.
In type 2 diabetes, the body doesn’t make enough insulin or doesn't use it properly. As a result, blood sugar (glucose) levels rise, leading to complications such as heart disease, kidney damage, and nerve problems.
Invokana works by blocking glucose from being reabsorbed by the kidneys. That raises the amount of glucose urinated, and lowers the amount of glucose in your blood.
The new drug is known as a selective sodium glucose co-transporter inhibitor, or SGLT2. Other drug companies are also working on this type of drug.
Other diabetes drugs work in differently. Some lower the amount of glucose made by the liver, while others stimulate the pancreas to release more insulin. And still many others work in different ways.
While Invokana isn't expected to replace other diabetes drugs, ''it's certainly promising," says Aaron Cypess, MD, PhD, of the Joslin Diabetes Center and an assistant professor of medicine at Harvard Medical School. "It's a mechanism we understand and that makes sense."
But, he says, he does not predict it will be the first drug doctors turn to when medication is needed to treat type 2 diabetes.
If lifestyle changes like diet, exercise, and weight loss don't control blood sugar enough, metformin is recommended first, says Richard Siegel, MD. That was spelled out in the 2012 American College of Physician treatment guidelines. Siegel is co-director of the Outpatient Diabetes Center at Tufts Medical Center and is an associate professor of medicine at the university's school of medicine in Boston.
Controlling blood sugar can lower the risk of complications such as heart disease, eye disease, and kidney and nerve problems.
In one of the Invokana studies, patients took the drug by itself. Other studies looked at results of the drug when used with other drugs, such as metformin.
A similar number of patients got their levels of A1c -- a test that measures blood sugar control -- down to the target of less than 7% whether they used Invokana alone or with metformin (45% and 46%, respectively, over a 26-week period). The same was true for how much weight they lost. People taking Invokana alone lost 8.5 pounds over 26 weeks, while those taking both drugs lost a little more than 9 pounds in the same time period.
Other side effects of Invokana include kidney problems, too much potassium in the blood, low blood sugar, and fainting.
Having more sugar in urine can be a problem, says Cypess, sometimes leading to urinary tract infections and yeast infections.
"It will make people go to the bathroom more often," McCall says. That could be a problem, he says, for men with an enlarged prostate (who already need to urinate frequently) or women with incontinence.
When the FDA approved Invokana, it asked Janssen to conduct post-marketing research on several areas, including any effects on the heart, pancreas, liver, and bones.
Last year, a similar drug, Forxiga (dapagliflozin), was turned down by the FDA. The agency cited concerns about breast and bladder cancer risk, among others. The drug was approved in Europe.
However, another benefit, possible weight loss, would be welcomed by many patients, McCall says. "You mention weight loss as a side effect of diabetes drugs and people perk up."