Diabetes presents a growing health concern in the United States. An estimated 18 million Americans have diabetes today, which is a startling increase from 5.8 million in 1980. Combined total and direct costs of the disease reached $132 billion in 2002. Managing diabetes appropriately can help to both decrease complications and increase quality of life.1
The FDA has approved Glumetza, a once-daily, extended-release formulation of metformin HCl, for the treatment of type 2 diabetes in adults. Depomed and King Pharmaceuticals have partnered for the production of Glumetza, and the companies have released Glumetza as 500-mg tablets. Glumetza will also be marketed in Canada. Glumetza may be used alone or in combination with other oral hypoglycemic agents.2
Metformin is currently available from various manufacturers in multiple formulations, including both immediate-and extended-release. A unique delivery system makes Glumetza different from other metformin products on the market. AcuForm technology allows Glumetza to be slowly released over 9 hours into the upper gastrointestinal (GI) tract, allowing for once-daily administration.
Glumetza is expected to increase patient compliance through once-daily dosing and decreased incidence of GI side effects. Up to 50% of patients using immediate-release metformin experience GI side effects, such as diarrhea, flatulence, nausea, vomiting, and abdominal discomfort.2,4,5 Although bothersome, side effects usually dissipate after several weeks of treatment. Side effects from immediate-release metformin can be minimized by beginning with an initial daily dose of 500 mg and gradually titrating upward.5 The improved side-effect panel of Glumetza is expected, however, to allow clinicians to treat diabetes more aggressively by prescribing higher doses earlier in the patient's treatment.2
Depomed assessed its 500-mg formulation in 2 double-blind clinical trials of >1000 patients. The studies lasted 24 to 48 weeks. Participants demonstrated excellent glycemic control, as determined by reductions in both hemoglobin A1C and fasting blood glucose.6
Mechanism of Action
Metformin reduces glucose levels by suppressing gluconeogenesis in the hepatic mitochondria and increasing skeletal muscle insulin sensitivity. It has been used alone and in combination with other hypoglycemic agents. Metformin's benefits extend past its hypoglycemic effects; metformin therapy has also been associated with decreased visceral fat, improved lipid panels, and decreased coronary atherosclerotic disease events.6
Although rare, lactic acidosis is a potential side effect of metformin therapy, and its outcomes can be fatal. Absolute contraindications for metformin include:
Nearly all instances of metformin-associated lactic acidosis have been in patients with contraindications. Although age is not an absolute contraindication, some clinicians recommend cautious use and careful monitoring of metformin use in patients over 80 years of age. Additionally, alcohol consumption and excessive acetaminophen use should be avoided during metformin therapy, as both agents may reduce the hepatic metabolism of lactic acid.3,6
Dr. Holmberg is a pharmacist with Phoenix Children's Hospital, Phoenix, Ariz.
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