Metformin

Chemical

Biguanide

Use

T2DM

Presentation

Tablets

Dose

500-3000mg/day

Route

PO

Onset

4-8hrs

MoA

Requires circulating insulin to work 

  1. Increases insulin sensitivity
    • Increases insulin receptor expression and tyrosine kinase activity
  1. Reduces glycogenolysis and hepatic gluconeogenesis
    • Activates hepatic AMP kinases
    • Inhibiting glucagon signalling
    • Overall reducing glycogenolysis & hepatic gluconeogenesis
  1. Reduces absorption of intestinal glucose
    • Inhibits intestinal disaccharidase
    • Delays monosaccharise absorption

PK

A

OBA 50% (fasted, reduced further w food)

D

90% PPB

M

No metabolism

E

Renally excreted unchanged

t1/2b 17.6hrs

Adverse Effects

Lactic acidosis in patients with renal impairment – binds to mitoch membrane inhibiting aerobic glycolysis →↑ ­anaerobic glycolysis →↑ ­lactate production

Nausea

Diarrhoea

Bloating

Wind

Contraindictions

Must be withheld 48hrs preop and before admin of iodinated IV contrast (lactic acidosis & AKI risk)