Co-author Dr. Bret Berner stated that, "With this extended-release formula, you can give the patients up to 2000 mg a day, which had not yet proven effective with other drugs."

"The new drug seems to improve the rapidity of initial titration but also patients' tolerability for higher doses, which might influence their adherence," said Dr. Berner, who is chief scientific officer and vice president of product development at Menlo Park, California-based Depomed, the maker of the extended-release metformin (Glumetza).

To determine the efficacy and safety of the medication, 700 type 2 diabetic patients were assigned to receive one of four treatments during 24 weeks: extended-release metformin at 1,500 mg once a day; extended-release metformin, 500 mg in the morning and 1000 mg at night; extended-release metformin in a single daily dose of 2000 mg; or 1,500 mg of immediate-release metformin twice daily.

By the end of the 12th week, mean levels of HbA1c had dropped significantly in all groups, the authors report.
At the end of week 24, the drops in both groups given 1,500 mg extended-release metformin were not significantly different from the drop observed in the immediate-release metformin group (-0.73%, -0.74%, and -0.70%, respectively). On the other hand, HbA1c levels dropped 1.06% in the group given a single dose of 2000 mg extended-release metformin.

These results differ from those obtained with other extended-release metformin formulations, when the once-daily treatments tended to be less effective than the twice-daily treatments, the researchers point out.