Rx
Only GLUMETZA® (metformin hydrochloride extended release tablets)
DESCRIPTION
GLUMETZA (metformin hydrochloride) extended release tablet is an oral antihyperglycemic drug used in the management of type 2 diabetes. Metformin hydrochloride (N,N-dimethylimidodicarbonimidic diamide hydrochloride) is not chemically or pharmacologically related to any other classes of oral antihyperglycemic agents. The structural formula of metformin hydrochloride (metformin HCl) is as shown:

Metformin HCl is a white to off-white crystalline compound with a molecular formula of CHN•HCl and a molecular weight of 165.63. Metformin HCl is freely soluble in water and is practically insoluble in acetone, ether, and chloroform. The pKa of metformin is 12.4. The pH of a 1% aqueous solution of metformin hydrochloride is 6.68. GLUMETZA tablets are modified release dosage forms that contain 500 mg or 1000 mg of metformin HCl. Each 500 mg tablet contains coloring, hypromellose, magnesium stearate, microcrystalline cellulose and polyethylene oxide. Each 1000 mg tablet contains colloidal silicon dioxide, polyvinyl alcohol, crospovidone, glyceryl behenate, polyacrylate dispersion, hypromellose, talc, polyethylene glycol, eudragit, titanium dioxide, simethicone emulsion, polysorbate and coloring. GLUMETZA 500 and 1000 mg tablets both utilize polymer-based, oral drug delivery systems, which allow delivery of metformin HCl to the upper gastrointestinal (GI) tract.

CLINICAL PHARMACOLOGY
Mechanism of Action
Metformin is an antihyperglycemic agent, which improves glucose tolerance in patients with type 2 diabetes, lowering both basal and postprandial plasma glucose. Its pharmacologic mechanisms of action are different from other classes of oral antihyperglycemic agents. Metformin decreases hepatic glucose production, decreases intestinal absorption of glucose, and improves insulin sensitivity by increasing peripheral glucose uptake and utilization. Unlike sulfonylureas, metformin does not produce hypoglycemia in either patients with type 2 diabetes or normal subjects (except in special circumstances, see  PRECAUTIONS ) and does not cause hyperinsulinemia. With metformin therapy, insulin secretion remains unchanged while fasting insulin levels and daylong plasma insulin response may actually decrease.

Pharmacokinetics
Absorption and Bioavailability

The following pharmacokinetic studies were performed with the 500 mg dosage form.

Following a single oral dose of 1000 mg (2x500 mg tablets) GLUMETZA after a meal, the time to reach maximum plasma metformin concentration (T) is achieved at approximately 7-8 hours. In both single and multiple-dose studies in healthy subjects, once daily 1000 mg (2x500 mg tablets) dosing provides equivalent systemic exposure, as measured by area-under-the-curve (AUC), and up to 35% higher C, of metformin relative to the immediate release given as 500 mg twice daily. GLUMETZA tablets must be administered immediately after a meal to maximize therapeutic benefit.

Single oral doses of GLUMETZA from 500 mg to 2500 mg resulted in less than proportional increase in both AUC and C. The mean C values were 473 ± 145, 868 ± 223, 1171 ± 297, and 1630 ± 399 ng/mL for single doses of 500, 1000, 1500, and 2500 mg, respectively. For AUC, the mean values were 3501 ± 796, 6705 ± 1918, 9299 ± 2833, and 14161 ± 4432 ng•hr/mL f