Metformin -Quick revision card
1st line oral agent -Type 2 diabetes insulin sensitizer-enhances insulin sensitivity by increasing both peripheral glucose uptake and utilization inhibits hepatic glucose production by various mechanisms ( reduces hepatic production of glucose , decreases intestinal absorption ) helps reduce LDL cholesterol and triglyceride levels prevents CV complications of diabetes ( reduces MI by 39 % and coronary deaths by 50 % UKPDS ) can lead to mild weight loss due to anorectic effect does not cause hypoglycemia ( rare )
Use in PCOS was to investigate the role of insulin resistance in the pathogenesis of the syndrome – evidence of use is conflicting
GI side effects ( diarrhoea ) ○ increases gl uptake in intestine -increases lactase conc , increases plasma GLP-1 conc , increases bile acid pool within the intestine and alters the microbiome Vitamin B12 and folate deficiency Lactic acidosis ( higher risk in subjects with CKD ) severe renal failure ( avoid GFR < 30 )
Immediate release 500 & 850 mg Oral solution 500 mg /mL Titrate dose slowly Usual maximum is 2gm daily Maximum recommended is 3 gm daily in 3 divided doses.
MR 500 mg and 750 mg tablets consider in adults who are intolerant of standard release metformin due to GI side effects
References
- McCreight, Laura J et al. “Metformin and the gastrointestinal tract.” Diabetologia vol. 59,3 (2016): 426-35. doi:10.1007/s00125-015-3844-9
- Medicine compendium https://www.medicines.org.uk/emc/product/6226/smpc#POSOLOGY
- Dumitrescu, R et al. “Metformin-clinical pharmacology in PCOs.” Journal of medicine and life vol. 8,2 (2015): 187-92.
