SILVER SPRING, Maryland (Reuters) - Drug makers should do more testing to see if proposed new diabetes medicines may damage patients' hearts, a prominent cardiologist told a U.S. advisory panel on Tuesday.
Other experts warned that tough standards could stifle development of new treatments by requiring longer and more expensive clinical trials. The U.S. market for the top-selling diabetes medicines now exceeds $6 billion.
"We have to rule out some level of harm prior to approval," Cleveland Clinic cardiologist Steven Nissen told a panel of experts that advises the Food and Drug Administration.
Nissen co-authored an analysis last year that found patients who took GlaxoSmithKline's pill Avandia had a higher chance of having a heart attack.
Another government-funded study found diabetics given intensive therapy to lower blood sugar died at a higher rate than others who were allowed a higher blood sugar level. It said no one drug was to blame.
Both studies raised questions about the FDA's current standard for judging diabetes drugs. Companies generally need to show only that the drugs control blood sugar.
The FDA, criticized for its oversight of Avandia and other drugs, is asking the panel of outside experts how much data to demand on cardiovascular effects for new and already approved diabetes drugs.
Recommendations are expected from the panel on Wednesday. The agency usually follows its panels' advice.
Nearly 24 million Americans have diabetes, the U.S. government estimates. Most cases are type 2 diabetes, which experts link with obesity, poor diet and lack of exercise.
Diabetics produce less insulin, or their bodies use it less effectively, which makes blood sugar rise. That can damage blood vessels and organs, leading to blindness, kidney disease, limb loss and heart disease.
Experts agree blood-sugar control helps prevent complications such as damage to the eyes and kidneys. But no conclusive evidence exists that any diabetes drug reduces heart disease, the top killer of diabetics, FDA officials said.
The agency will request a long-term trial on heart risks if mid- and late-stage testing raises concern, Hylton Joffe, lead medical officer in the FDA's diabetes drug group, said. The question remains if all diabetes drugs need cardiovascular testing to show they benefit the heart, or do not harm it.
That requirement would "set a very high hurdle that would affect the availability of new drugs," Joffe said.
Nissen, a vocal FDA critic, said the agency should make companies collect enough data to rule out a certain level of cardiac harm before approval. The FDA also should mandate that companies start a long-term study of heart-related effects before they can sell a new medicine, he said.
The proposal could "modestly" slow a drug's path to the market by about six to 12 months, Nissen said.
"We can still get drugs to patients in a speedy fashion," he said.
Diabetes medicines are among the biggest sellers. U.S. sales of the leading drugs exceeded $6 billion in 2007, according to healthcare information company IMS Health.
The top sellers include Glaxo's Avandia and Takeda Pharmaceutical Co's rival Actos.
Merck & Co Inc's Januvia and Eli Lilly and Amylin Pharmaceuticals Inc's Byetta are newer drugs that have gained market share recently.
Glaxo has said Avandia's safety is comparable to similar pills. The company agreed to add a strong warning, however, that the drug might increase heart attack risk with a note that the data is inconclusive. Studies of cardiac effects are continuing.
Reporting by Lisa Richwine; editing by Tim Dobbyn