WASHINGTON (Reuters) - GlaxoSmithKline Plc’s diabetes drug Avandia stimulates the action of a cell that drives the normal bodily process of reabsorbing bone, making bones more apt to break, researchers said on Sunday.
Previous studies had established a heightened risk for bone fractures among women taking Avandia, the top-selling diabetes drug. The new research, published in the journal Nature Medicine, offered an explanation.
The fracture risk previously was attributed to the drug acting to inhibit cells called osteoblasts that build bone. The new study, involving mice, found the drug also can undermine bone strength by boosting the action of osteoclasts, cells that naturally degrade bone.
“Part of normal bone remodeling is the balance between deposition of new bone and the removal of old bone,” Ronald Evans, a professor of biology at the Salk Institute for Biological Studies in La Jolla, California who led the study, said a telephone interview.
“And for normal people there’s a balance. And if you’re in balance, for every bit of bone that you take away, you make new bone,” Evans said. “And what happens when you’re on the drug is it stimulates the cell that wants to take bone away and it also decreases the interest of the cell that wants to make bone.”
Evans said people with diabetes who take Avandia could take drugs to counteract the fracture risk.
“I do not recommend that anyone goes off of the drug. But you have to know that there is this potential risk. And therefore it should be monitored,” Evans said.
Avandia, known generically as rosiglitazone, also has been linked to increased risk of heart attack. The U.S. Food and Drug Administration said last month Avandia will carry a “black box” warning that it could cause chest pain or heart attacks.
Mary Anne Rhyne, a GlaxoSmithKline spokeswoman, said the study “adds additional context” to the already known fracture risk for people using the drug.
“We’ve got a preclinical and clinical program ongoing to better understand the underlying mechanism of fractures,” Rhyne said.
Editing by Maggie Fox and John O'Callaghan