METFORMIN TABLETS 500 MG - patient leaflet, side effects, dosage

2. what you need to know before you take metformin tablets

Do not take Metformin Tablets if you:

! are allergic to metformin hydrochloride or any of the other ingredients of this medicine (listed in section 6).

! have severely reduced kidney function.

! have uncontrolled diabetes, with, for example, severe hyperglycaemia (high blood glucose), nausea, vomiting, diarrhoea, rapid weight loss, lactic acidosis (see section “Risk of lactic acidosis” below) or ketoacidosis. Ketoacidosis is a condition in which substances called ‚ketone bodies‘ accumulate in the blood and which can lead to diabetic pre-coma. Symptoms include stomach pain, fast and deep breathing, sleepiness or your breath developing an unusual fruity smell.

! have had diabetic coma, or ketoacidosis.

! have recently had a serious infection, injury or operation.

! are dehydrated, or you have been vomiting or have had diarrhoea recently.

! suffer from heart disease (e.g. heart failure) or you have had a recent heart attack.

! have chronic liver disease.

! have lactic acidosis, shock (a problem with your circulation causing a sudden drop in blood flow through the body) or lung problems causing breathing difficulty (pulmonary insufficiency).

! have any condition associated with an abnormally low amount of oxygen in the blood (hypoxaemia).

! drink a lot of alcohol.

! have had, or need to have, an injection of a contrast medium that contains iodine into your bloodstream, for example in the context of an X-ray or scan.

Warnings and precautions

Talk to your doctor or pharmacist before taking Metformin Tablets.

Risk of lactic acidosis

Metformin may cause a very rare, but very serious side effect called lactic acidosis, particularly if your kidneys are not working properly. The risk of developing lactic acidosis is also increased with uncontrolled diabetes, serious infections i.e. sepsis, prolonged fasting or excessive alcohol intake, dehydration (see further information below), cardiorespiratory problems and any medical conditions in which a part of the body has a reduced supply of oxygen (such as acute severe heart disease). If any of the above apply to you, talk to your doctor for further instructions.

Stop taking Metformin Tablets for a short time if you have a condition that may be associated with dehydration (significant loss of body fluids) such as severe vomiting, diarrhoea, fever or if you drink less fluid than normal. Talk to your doctor for further instructions.

Stop taking Metformin Tablets and contact a doctor or the nearest hospital immediately if you experience some of the symptoms of lactic acidosis , as this condition may lead to coma. Symptoms of lactic acidosis include: ! vomiting

! stomach ache (abdominal pain)

• ! muscle cramps

! a general feeling of not being well with severe tiredness

! difficulty in breathing

! reduced body temperature and heartbeat

Lactic acidosis is a medical emergency and must be treated in a hospital.

If you need to have a major surgery, you must stop taking Metformin Tablets during and for some time after the procedure. Your doctor will decide when you must stop and when to restart your treatment with Metformin Tablets.

During treatment with Metformin Tablets, your doctor will check your kidney function at least once a year or more frequently if you are elderly and/or if you have worsening kidney function.

Other medicines and Metformin Tablets

Tell your doctor if you are taking, have recently taken or might take any other medicines. You may need more frequent blood glucose and kidney function tests, or your doctor may need to adjust the dosage of Metformin Tablets. It is especially important to tell your doctor if you are taking:

! medicines which increase urine production (diuretics).

! medicines used to treat pain and inflammation (NSAID and COX-2-inhibitors, such as ibuprofen and celecoxib).

! certain medicines for the treatment of high blood pressure (ACE inhibitors and angiotensin II receptor antagonists).

! other medicines to treat diabetes (insulin).

! medicines that may change the amount of Metformin in your blood, especially if you have reduced kidney function (cimetidine).

! medicines that help prevent blood clots (anticoagulants such as warfarin).

! medicines to treat itchiness (ketotifen).

! monoamine oxidase inhibitors (MAOIs) used to treat depression such as tranylcypromine, phenelzine and isocarboxazid.

! hormonal medicines to treat cancer (octreotide).

If you have to see the dentist, go to the hospital for an operation or treatment, or are seen by a different doctor for any reason, make sure that they know you have diabetes and that you are taking metformin. This is very important if you are to be given an anaesthetic or have to stop eating and drinking for a while before any medical tests are carried out. If you need to have an injection of a contrast medium that contains iodine into your bloodstream, for example in the context of an X-ray or scan, you must stop taking Metformin Tablets before or at the time of the injection. Your doctor will decide when you must stop and when to restart your treatment with Metformin Tablets.

The control of your blood sugar levels must be regularly monitored while taking metformin, as usual.

Your doctor may need to carry out regular blood tests whilst you are taking this medicine in order to monitor the control of your diabetes, vitamin B12 levels and kidney function.

Metformin Tablets with alcohol

Avoid drinking too much alcohol while taking Metformin Tablets since this may increase the risk of lactic acidosis (see section “Warnings and precautions”).

Pregnancy and breast-feeding

Metformin Tablets are not recommended if you are pregnant or breast-feeding.

If you are pregnant or breast-feeding, think you may be pregnant or are planning to have a baby, ask your doctor or pharmacist for advice before taking this medicine.

Driving and using machines

Patients taking metformin alone do not usually become hypoglycaemic. However, if you are also taking sulphonylureas, hypoglycaemia may occur; in which case the normal caution with driving or operating machines should be observed.

Sodium content

Metformin 500mg Tablets – This medicine contains 4.7 mg sodium (main component of cooking/table salt) in each tablet. This is equivalent to 0.24% of the recommended maximum daily dietary intake of sodium for an adult.

Metformin 850mg Tablets – This medicine contains 8 mg sodium (main component of cooking/table salt) in each tablet. This is equivalent to 0.4% of the recommended maximum daily dietary intake of sodium for an adult.

Propylene glycol content

Metformin 500mg Tablets – This medicine contains 0.323 mg propylene glycol in each tablet which is equivalent to 1.938 mg/dose.

Metformin 850mg Tablets – This medicine contains 0.526 mg propylene glycol in each tablet which is equivalent to 1.841 mg/dose.

3. how to take metformin tablets

Always take this medicine exactly as your doctor or pharmacist has told you. Check with your doctor or pharmacist if you are not sure.

Recommended doses follow. Doctors sometimes prescribe different doses to these: if this applies to you, discuss it with your doctor, if you have not already done so. You should always follow your doctor's instruc­tions as to how and when to take your medicine. Your pharmacist may be able to advise if you are not sure. Exactly how many tablets to take and when to take them will be written on the label. Please read it carefully.

Metformin Tablets should be swallowed whole with a drink of water, with meals.

Adults and elderly patients without kidney problems:

The usual initial dose of metformin is one 500mg tablet 3 times daily, or one 850mg tablet twice daily. Control of your diabetes may occur in a few days, but can often take up to 2 weeks. The dose may be slowly increased by your doctor, if necessary, to a maximum dose of 3,000mg (3g) daily. Once control is obtained your doctor may decide to reduce your dosage.

If you have reduced kidney function:

Your doctor may prescribe a lower dose.

Children:

Metformin Tablets are not recommended for children.

If you take more Metformin Tablets than you should

If you take one extra dose, this may unbalance the control of your diabetes especially if you are also taking other medicines. Contact your doctor if you are worried about this. If you, or anyone else has taken more tablets than you should, contact your nearest hospital accident and emergency department straight away. Lactic acidosis may develop if you take more Metformin Tablets than you should (see section 2, „Warnings and precautions“.

If you forget to take Metformin Tablets

If you forget to take a dose, take the missed dose as soon as you remember. If your next dose is due within 2 hours take a single dose now and miss the next dose. Do not take a double dose to make up for a forgotten dose. Continue with your treatment at the correct times.

If you stop taking Metformin Tablets

You should finish all the tablets your doctor has prescribed. Do not stop taking your medicine, even if you feel better, as it may be dangerous to stop taking the medicine without your doctor's advice.

If you have any further questions on the use of this medicine, ask your doctor or pharmacist.

4. possible side effects

Like all medicines, this medicine can cause side effects, although not everybody gets them.

As with all medicines, Metformin Tablets may have unwanted effects in some patients, particularly when they first start to take them. Stomach upsets such as nausea, diarrhoea, abdominal pain or vomiting but taking your tablets with or after meals may reduce this. The effects may wear off as treatment continues and the diabetes becomes controlled. Another common side effect is a metallic taste in the mouth. If you suffer badly from these effects, contact your doctor who might lower your dose temporarily.

You may absorb less vitamin B12 from your diet which, if not recognised early, could result in anaemia. If there is a tendency to bruise easily, you bleed from the gums or elsewhere, you become less resistant to infections, or you feel very tired and look pale, see your doctor. Your blood glucose level may become too low (hypoglycaemia) though this is less likely than with sulphonylurea drugs for diabetes.

Metformin Tablets may cause a very rare but very serious side effect called lactic acidosis (see section “Warnings and precautions"). If this happens you must stop taking Metformin Tablets and contact a doctor or the nearest hospital immediately, as lactic acidosis may lead to coma.

Other side effects that you may also experience include anorexia, redness of the skin (erythema), an itchy rash (urticaria), itching, inflammation of the liver (hepatitis) and skin rashes.

If you have any of these effects and they become worse, inconvenient or upsetting, see your doctor or pharmacist.

If you experience any other unpleasant effects which you think could be caused by this medicine, you should contact your doctor or pharmacist for advice.

Reporting of side effects

If you get any side effects, talk to your doctor, pharmacist or nurse. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via the MHRA Yellow Card Scheme at: or search for MHRA Yellow Card in the Google Play or Apple App Store. By reporting side effects you can help provide more information on the safety of this medicine.

5. how to store metformin tablets

Keep this medicine out of the sight and reach of children.

Do not use this medicine after the expiry date which is stated on the carton. The expiry date refers to the last day of that month.

Store below 25°C in a dry place.

Do not use this medicine if you notice any defects in the tablets, such as broken or chipped tablets, take them to your pharmacist for advice.

Do not throw away any medicines via wastewater or household waste. Ask your pharmacist how to throw away medicines you no longer use. These measures will help protect the environment.

6. contents of the pack and other information

What Metformin Tablets contain

The active substance is metformin hydrochloride. Each film-coated tablet contains 500mg or 850mg of metformin hydrochloride.

The other ingredients are sodium starch glycollate, maize starch, povidone, colloidal anhydrous silica, magnesium stearate, methylhydroxy­propylcellulo­se, propylene glycol, polyethylene glycol, purified talc, and titanium dioxide (E171).

What Metformin Tablets look like and contents of the pack

Metformin Tablets are supplied in packs of 28, 30, 56, 60, 84, 90, 100 or 112 tablets. However, the quantity dispensed by the pharmacist will be according to your prescription.

Not all pack sizes may be marketed.

Marketing Authorisation Holder

Ennogen Healthcare Limited

Unit G2-G4, Riverside Industrial Estate, Riverside Way, Dartford, DA1 5BS, United Kingdom.

Manufacturer

Sandoz Limited, 200 Frmley Business Park, Frmley, Camberley, GU16 7SR, UK

This leaflet was last revised in October 2021.

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