Feb. 22, 2007 -- Women taking the diabetes drugs Avandia, Avandamet, or Avandaryl may be more likely to fracture their bones than those using other diabetes drugs.

That's according to the FDA and GlaxoSmithKline, maker of Avandia, Avandamet, and Avandaryl. Those three drugs share the same active ingredient: rosiglitazone.

Doctors should consider fracture risk when treating diabetic women with Avandia, Avandamet, or Avandaryl, advises the FDA and GlaxoSmithKline, a WebMD sponsor.

GlaxoSmithKline notified doctors of the possible risk in a letter dated February 2007. That letter is posted on the FDA's web site.

It explains that possible fracture risk surfaced in a study of 4,351 patients recently diagnosed with type 2 diabetes.

Patients in the study were randomly assigned to take one of the following diabetes drugs:

• Rosiglitazone, the key ingredient in Avandia, Avandamet, and Avandaryl
• Metformin, which is sold generically and under the brand name Glucophage
• Glyburide, sold generically and under the brand names Diabeta and Micronase

Patients were followed for four to six years as they took their assigned drugs.

During that time, women taking rosiglitazone were more likely to have bone fractures than women taking either metformin or glyburide.

This problem was not seen in men taking rosiglitazone.

Most of the fractures seen in the women taking rosiglitazone affected bones in the upper arm, hand, or foot.

Bones often affected by osteoporosis (such as the hip or spine) weren't more likely to fracture in the women on rosiglitazone.

The study's findings are mirrored in early results from another, ongoing study, according to GlaxoSmithKline.

It's not yet known how the drugs affect women's fracture risk, or how significant the findings are for typical diabetes patients.

Further research is underway, the drugmaker says.