Pharmacy Diabetes

Biguanides_Metformin-formulations imediate release

Metformin Hydrochloride Immediate Release

  • Immediate release tablets in 500mg, 850mg and 1000mg strengths.
  • Care should be taken not to crush or chew the tablets.
  • Tablets should be taken in divided doses throughout the day, with meals.

  • Treatment of type 2 diabetes in adults where physical activity and dietary management has not resulted in adequate glycaemic targets.
  • Metformin immediate release has also been indicated for the treatment of type 2 diabetes in children over the age of 10.

  • Initially 500mg should be taken once or twice a day and the dose increased gradually over one to two weeks. A slow increase in dose may improve the renown gastrointestinal side effects.
  • Maximum dose for the immediate release Metformin is 3000g daily.
  • The action of metformin continues to reach its peak over approximately 21 days.

  • Initial and maintenance dosing should always be individualized based on both renal and liver function.
  • Due to the potential of changes in renal function, the dose should be adjusted based on renal function, with regular reviews undertaken.

  • Lactic acidosis - Life threatening lactic acidosis can occur due to metformin accumulating in susceptible individuals. Early warning symptoms include anorexia, nausea, vomiting, abdominal pain and cramps. metformin. Risks factors include renal dysfunction, old age, and doses of metformin >2g daily. It can also be associated with prolonged fasting, excessive alcohol, and hepatic dysfunction.
  • Surgery - Discontinue Metformin 48 hours before surgery, if possible. It is common practice not to restart Metformin for 2 days after surgery and once the individual is eating and drinking normally.
  • Kidney Function - Metformin is entirely renally excreted by the kidney and will accumulate with renal insufficiency. Check creatinine clearance and/or serum creatinine levels before starting treatment and regularly thereafter (annually for those individuals with normal renal function). Renal function should be checked at least two to four times a year for those whose serum creatinine levels are at the upper limit of normal and for elderly individuals. Current recommendations for metformin are CrCl 60-90 mL/min dose of metformin 2g daily, 30-60 mL/minute 1g daily. Metformin should be ceased if eGFR falls below 30 mL/min/1.73m

  • Gastrointestinal- diarrhoea, nausea, vomiting, abdominal pain, and loss of appetite. Starting with a low dose and increasing slowly can help with these side effects.
  • Taking medicine with meals can also reduce the unwanted effects. Altered taste is also commonly reported with Metformin. Reduced vitamin B12 absorption.
  • Dermatological -skin reactions including urticaria, erythema, and pruritus.
  • Lactic acidosis
  • Isolated reports of liver function test abnormalities or hepatitis. These often resolve after the Metformin is ceased.

  • Hypersensitivity to Metformin or any of the excipients. Renal dysfunction or any acute condition that has the potential to lower renal function (dehydration, severe infection, shock, contrast dye).
  • Diabetic ketoacidosis.
  • Renal failure or renal dysfunction.
  • Any acute condition that has the potential to lower renal function (dehydration, severe infection, shock, contrast dye).
  • Major surgery.
  • Severe hepatic dysfunction.
  • Acute or chronic disease that can cause tissue hypoxia (cardiac failure, MI, pancreatitis, sepsis).

Metformin is absorbed through the entire gastrointestinal mucosa. Studies have shown there is a lack of dose proportionally with increasing doses thought to be due to a reduction of absorption. It is therefore thought that metformin absorption is saturable and incomplete. 

Plasma protein binding of metformin is negligible.

Renal clearance of metformin is > 400 mL/min, indicating that metformin is eliminated by glomerular filtration and tubular secretion. Dosage adjustment should therefore occur in those with renal dysfunction and ceased in renal failure. 

For more detailed information on this product please consult the product information. 

For more detailed information on this product please consult the product information.