Drug reference
Metformin exerts its effect mainly by decreasing gluconeogenesis and by increasing peripheral utilisation of glucose; since it acts only in the presence of endogenous insulin it is effective only if there are some residual functioning pancreatic islet cells. Endocrine system
PDF page 752
Type 2 diabetes mellitus [monotherapy or in combination with other antidiabetic drugs (including insulin)] ▶BY MOUTH USING IMMEDIATE-RELEASE MEDICINES ▶Child 10–17 years (specialist use only): Initially 500 mg once daily, dose to be adjusted according to response at intervals of at least 1 week, maximum daily dose to be given in 2–3 divided doses; maximum 2 g per day ▶Adult: Initially 500 mg once daily for at least 1 week, dose to be taken with breakfast, then 500 mg twice daily for at least 1 week, dose to be taken with breakfast and evening meal, then 500 mg 3 times a day, dose to be taken with breakfast, lunch and evening meal; maximum 2 g per day ▶BY MOUTH USING MODIFIED-RELEASE MEDICINES ▶Adult: Initially 500 mg once daily, then increased if necessary up to 2 g once daily, dose increased gradually, every 10–15 days, dose to be taken with evening meal, alternatively increased to 1 g twice daily, dose to be taken with meals, alternative dose only to be used if control not achieved with once daily dose regimen. If control still not achieved then change to standard release tablets Type 2 diabetes mellitus [reduction in risk or delay of onset] ▶BY MOUTH USING MODIFIED-RELEASE MEDICINES ▶Adult 18–74 years: Initially 500 mg once daily, then increased if necessary up to 2 g once daily, dose increased gradually, every 10–15 days, dose to be taken with evening meal, for further information on risk factors—consult product literature Polycystic ovary syndrome ▶BY MOUTH USING IMMEDIATE-RELEASE MEDICINES ▶Adult: Initially 500 mg once daily for 1 week, dose to be taken with breakfast, then 500 mg twice daily for 1 week, dose to be taken with breakfast and evening meal, then 1.5–1.7 g daily in 2–3 divided doses l UNLICENSED USE ▶In adults g Based on clinical experience of increased side-effects, maximum dose for metformin immediate- release medicines in BNF Publications differs from product licence. l Not licensed for polycystic ovary syndrome.
PDF page 752
Acute metabolic acidosis (including lactic acidosis and diabetic ketoacidosis)
PDF page 752
Risk factors for lactic acidosis CAUTIONS, FURTHER INFORMATION ▶Risk factors for lactic acidosis Manufacturer advises caution in chronic stable heart failure (monitor cardiac function), and concomitant use of drugs that can acutely impair renal function; interrupt treatment if dehydration occurs, and avoid in conditions that can acutely worsen renal function, or cause tissue hypoxia. ▶Elderly Prescription potentially inappropriate (STOPP criteria) if eGFR less than 30 mL/minute/1.73 m2 (risk of lactic acidosis). See also Prescribing in the elderly p. 33.
PDF page 752
▶In adults Patients taking up to 2 g daily of the standard- release metformin may start with the same daily dose of metformin modified release; not suitable if dose of standard-release tablets more than 2 g daily.
PDF page 752
GLUCOPHAGE ® SR Scottish Medicines Consortium (SMC) decisions The Scottish Medicines Consortium has advised (October 2009) that Glucophage ® SR is accepted for restricted use within NHS Scotland for the treatment of type 2 diabetes mellitus in adult patients who are intolerant of standard- release metformin, and in whom the prolonged-release tablet allows the use of a dose of metformin not previously tolerated, or in patients for whom a once daily preparation offers a clinically significant benefit.
PDF page 752
→Appendix 1: metformin
PDF page 752
▶Common or very common Abdominal pain. appetite decreased. diarrhoea (usually transient). gastrointestinal disorder. nausea. taste altered. vomiting ▶Rare or very rare Hepatitis. lactic acidosis (discontinue). skin reactions. vitamin B12 absorption decreased SIDE-EFFECTS, FURTHER INFORMATION Gastro-intestinal side-effects are initially common with metformin, and may persist in some patients, particularly when very high doses are given. A slow increase in dose may improve tolerability.
PDF page 752
Can be used in pregnancy for both pre- existing and gestational diabetes. Women with gestational diabetes should discontinue treatment after giving birth.
PDF page 752
May be used during breast-feeding in women with pre-existing diabetes.
PDF page 752
Withdraw if tissue hypoxia likely.
PDF page 752
▶In adults Manufacturer advises avoid if eGFR is less than 30 mL/minute/1.73 m2. ▶In children Manufacturer advises avoid if estimated glomerular filtration rate is less than 30 mL/minute/ 1.73 m2. Dose adjustments ▶In children Manufacturer advises consider dose reduction in moderate impairment. ▶In adults Manufacturer advises reduce dose in moderate impairment—consult product literature.
PDF page 752
Determine renal function before treatment and at least annually (at least twice a year in patients with additional risk factors for renal impairment, or if deterioration suspected).
PDF page 752
There can be variation in the licensing of different medicines containing the same drug. Forms available from special-order manufacturers include: capsule, oral suspension, oral solution Modified-release tablet CAUTIONARY AND ADVISORY LABELS 21, 25 ▶Metformin hydrochloride (Non-proprietary) Metformin hydrochloride 750 mg Sukkarto SR 750mg tablets | 56 tablet P £2.97 DT = £6.40 ▶Bolamyn SR (Teva UK Ltd) Metformin hydrochloride 500 mg Bolamyn SR 500mg tablets | 28 tablet P £3.20 | 56 tablet P £6.40 DT = £4.00 Metformin hydrochloride 1 gram Bolamyn SR 1000mg tablets | 28 tablet P £5.06 ▶Diagemet XL (Genus Pharmaceuticals Ltd) Metformin hydrochloride 500 mg Diagemet XL 500mg tablets | 28 tablet P £1.49 ▶Glucient SR (Consilient Health Ltd) Metformin hydrochloride 500 mg Glucient SR 500mg tablets | 28 tablet P £2.51 | 56 tablet P £5.03 DT = £4.00 Metformin hydrochloride 750 mg Glucient SR 750mg tablets | 28 tablet P £3.20 Metformin hydrochloride 1 gram Glucient SR 1000mg tablets | 28 tablet P £4.26 | 56 tablet P £8.52 DT = £6.40 ▶Glucophage SR (Merck Serono Ltd) Metformin hydrochloride 500 mg Glucophage SR 500mg tablets | 28 tablet P £1.99 | 56 tablet P £4.00 DT = £4.00 Metformin hydrochloride 750 mg Glucophage SR 750mg tablets | 28 tablet P £3.20 | 56 tablet P £6.40 DT = £6.40 Metformin hydrochloride 1 gram Glucophage SR 1000mg tablets | 28 tablet P £3.20 | 56 tablet P £6.40 DT = £6.40 ▶Meijumet (Medreich Plc) Metformin hydrochloride 500 mg Meijumet 500mg modified- release tablets | 28 tablet P £2.00 | 56 tablet P £4.00 DT = £4.00 Metformin hydrochloride 750 mg Meijumet 750mg modified- release tablets | 28 tablet P £3.20 | 56 tablet P £6.40 DT = £6.40 Metformin hydrochloride 1 gram Meijumet 1000mg modified- release tablets | 28 tablet P £3.20 | 56 tablet P £6.40 DT = £6.40 ▶Metabet SR (Morningside Healthcare Ltd) Metformin hydrochloride 500 mg Metabet SR 500mg tablets | 28 tablet P £2.61 | 56 tablet P £5.22 DT = £4.00 Metformin hydrochloride 1 gram Metabet SR 1000mg tablets | 28 tablet P £4.53 | 56 tablet P £9.06 DT = £6.40 ▶Metuxtan SR (Accord Healthcare Ltd) Metformin hydrochloride 500 mg Metuxtan SR 500mg tablets | 28 tablet P £1.99 | 56 tablet P £5.32 DT = £4.00 ▶Sukkarto SR (Morningside Healthcare Ltd) Metformin hydrochloride 500 mg Sukkarto SR 500mg tablets | 56 tablet P £2.38 DT = £4.00 Metformin hydrochloride 1 gram Sukkarto SR 1000mg tablets | 56 tablet P £3.82 DT = £6.40 ▶Yaltormin SR (Wockhardt UK Ltd) Metformin hydrochloride 500 mg Yaltormin SR 500mg tablets | 28 tablet P £1.20 | 56 tablet P £2.39 DT = £4.00 Metformin hydrochloride 750 mg Yaltormin SR 750mg tablets | 28 tablet P £1.44 | 56 tablet P £2.88 DT = £6.40 Metformin hydrochloride 1 gram Yaltormin SR 1000mg tablets | 28 tablet P £1.92 | 56 tablet P £3.83 DT = £6.40 Tablet CAUTIONARY AND ADVISORY LABELS 21 ▶Metformin hydrochloride (Non-proprietary) Metformin hydrochloride 500 mg Metformin 500mg tablets | 28 tablet P £2.88 DT = £1.36 | 84 tablet P £2.30–£4.13 | 500 tablet P £18.75–£24.29 Metformin hydrochloride 850 mg Metformin 850mg tablets | 56 tablet P £2.56 DT = £1.34 | 300 tablet P £7.18–£8.86 ▶Glucophage (Merck Serono Ltd) Metformin hydrochloride 500 mg Glucophage 500mg tablets | 84 tablet P £2.88 Metformin hydrochloride 850 mg Glucophage 850mg tablets | 56 tablet P £3.20 DT = £1.34 Oral solution CAUTIONARY AND ADVISORY LABELS 21 ▶Metformin hydrochloride (Non-proprietary) Metformin hydrochloride 100 mg per 1 ml Metformin 500mg/5ml oral solution sugar-free | 100 ml P £4.50–£5.74 sugar-free | 150 ml P £60.00 DT = £6.75 Metformin hydrochloride 170 mg per 1 ml Metformin 850mg/5ml oral solution sugar-free | 150 ml P £19.95 DT = £19.95 Metformin hydrochloride 200 mg per 1 ml Metformin 1g/5ml oral solution sugar-free | 150 ml P £24.00 DT = £24.00 Combinations available: Alogliptin with metformin, p. 732. Canagliflozin with metformin, p. 742. Dapagliflozin with metformin, p. 744. Empagliflozin with metformin, p. 746. Linagliptin with metformin, p. 732. Pioglitazone with metformin, p. 750. Saxagliptin with metformin, p. 733. Sitagliptin with metformin, p. 734. Vildagliptin with metformin, p. 735 BLOOD GLUCOSE LOWERING DRUGS › DIPEPTIDYLPEPTIDASE-4 INHIBITORS (GLIPTINS)
PDF pages 752, 753
Manufacturer advises that patients and their carers should be informed of the risk of lactic acidosis and told to seek immediate medical attention if symptoms such as dyspnoea, muscle cramps, abdominal pain, hypothermia, or asthenia occur. Medicines for Children leaflet: Metformin for diabetes www.medicinesforchildren.org.uk/metformin-diabetes
PDF page 752
Initially 500 mg once daily for at least 1 week,
First-line fragment. Read the complete Indications and Dose section above.
PDF page 752
Initially 500 mg once daily, then increased if
First-line fragment. Read the complete Indications and Dose section above.
PDF page 752
Initially 500 mg once daily, then
First-line fragment. Read the complete Indications and Dose section above.
PDF page 752
Initially 500 mg once daily for 1 week, dose to be
First-line fragment. Read the complete Indications and Dose section above.
PDF page 752
