Core pharmacology

Class Group

Biguanides

Legacy Cicm Level

Level 3

Indications Uses

treatment of non-insulin-dependent
(type II) diabetes mellitus

Presentation

As 500/850 mg tablets of metformin hydrochloride
MR also available.

Main Action

Hypoglycaemia

Mechanism of action

- Enhance peripheral action of insulin
- ↑ rate of anaerobic glycolysis and ↓ rate of gluconeogenesis
- Inhibit intestinal absorption and ↓ peripheral utilization of glucose

Physiological effects

CVS:
- ↓ intestinal absorption of glucose, folate, vit B12
- no effect on gastric motility
- ↑ utilization of glucose and cause weight loss
Metabolic/Other:
- ↑ sensitivity to peripheral actions of insulin by ↑ no of low affinity binding sites (RBC, Adipocytes, hepatocytes, sk. Muscle)
- inhibits metabolism of lactate and ↓ plasma TG, cholesterol, pre-beta lipoprotein

Adverse Effects Toxicity

- Does not cause hypoglycaemia when used on its own
- GI disturbances
- Lactic acidosis (rare)

Absorption

Slowly absorbed from small intestine
PO BA: 50-60%

Protein binding

Not protein bound

Metabolism

No metabolites

Excretion

Unchanged in urine

Clearance

> GFR (Active tubular secretion)

Half-life

Elimination half life 1.7-4.5 hrs

Special Points

Not recommended in renal impairment

Route And Dose

PO
1-3gm daily in divided doses