Metformin
Chemical
Biguanide
Use
T2DM
Presentation
Tablets
Dose
500-3000mg/day
Route
PO
Onset
4-8hrs
MoA
Requires circulating insulin to work
- Increases insulin sensitivity
- Increases insulin receptor expression and tyrosine kinase activity
- Reduces glycogenolysis and hepatic gluconeogenesis
- Activates hepatic AMP kinases
- Inhibiting glucagon signalling
- Overall reducing glycogenolysis & hepatic gluconeogenesis
- 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)