Antidiabetic Agent, Biguanide
Metformin is an oral biguanide used to improve glycemic control in adult and pediatric patients 10 years and older with type 2 diabetes mellitus (T2DM).

Metformin decreases hepatic gluconeogenesis production, decreases intestinal absorption of glucose, and improves insulin sensitivity by increasing peripheral glucose uptake and utilization.

1.Distribution: Vd: 654 ± 358 L.
2.Protein binding: Negligible.
3.Half-life elimination: Plasma: 4 to 9 hours; Blood ~17.6 hours.
4.Excretion: Urine (90% as unchanged drug; active secretion).

Hypersensitivity to metformin or any component of the formulation; severe renal dysfunction (eGFR <30 mL/minute/1.73 m2); acute or chronic metabolic acidosis with or without coma (including diabetic ketoacidosis).

Metformin crosses the placenta; concentrations may be comparable to or higher than those found in the maternal plasma

Metformin is present in breast milk.

Significant:
Gastrointestinal effects、Lactic acidosis、Vitamin B12 deficiency
Common:
Diarrhea、flatulence、nausea and vomiting

Diabetes mellitus, type 2, treatment:
1.Immediate release:
Initial: Oral: 500 mg once or twice daily or 850 mg once daily.
Usual maintenance dosage: Oral: 1 g twice daily or 850 mg twice daily.
2.Extended release:
Initial: Oral: 500 mg to 1 g once daily.Maximum: 2 g/day.

1.eGFR 60 mL/minute/1.73 m2: No dosage adjustment necessary. Monitor renal function at least annually.
2.eGFR >45 to <60 mL/minute/1.73 m2: No dosage adjustment necessary.(increase monitoring of renal function)
3.eGFR 30 to 45 mL/minute/1.73 m2:Use generally not recommended .
4.eGFR <30 mL/minute/1.73 m2: Use is contraindicated.