Overview of metformin: special focus on metformin extended release.

INTRODUCTION: Diabetes is characterized by chronic hyperglycemia and vascular alterations, leading to micro-vascular and macro-vascular complications, which account for increased morbidity and mortality associated with the disease. Cardiovascular complications are the leading cause of death in patients with diabetes. Due to its cardio-protective effects, metformin is recommended as the initial agent of choice in the treatment of T2DM. Results of UKPDS, one of the largest and longest studies, showed reductions in cardiovascular mortality in patients using metformin. AREAS COVERED: This article reviews the history, structure, pharmacokinetics, clinical efficacy, and safety of extended-release metformin (XR). It also highlights fact that its use has been shown to have the same clinical and metabolic benefits as standard metformin, but also improved adherence and reduced side effects. The paper provides a side-by-side comparison of the main differences in the use of metformin XR versus metformin IR, i.e., their effect on lipids, and gastrointestinal (GI) side effects. Studies included in this review were selected from PUBMED and Embase databases. EXPERT OPINION: Given the chronic nature of diabetes, patient's adherence to therapy is very important in preventing complications of the disease. Compliance with the standard metformin formulation can be poor, due to multiple daily dosing and frequent GI side effects. Metformin XR can be given once daily and is associated with less GI side effects compared to immediate release metformin (IR); This leads to increased compliance, improved glycemic control and hence decreased risk of the associated micro- and macro-vascular complications.