Metformin

The recommended adult dose of metformin ranges from 500 mg 3 or 4 times a day to 850 mg 2 or 3 times a day. The maximum daily dose should not exceed 2,550 mg. Tablets should be taken with food whenever possible to reduce the risk of nausea and vomiting. Metformin may be used alone or with other medications that reduce blood sugar. To ensure that the medication is working well, monitor your blood glucose on a regular basis as directed by your doctor or diabetes educator.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take Metformin exactly as prescribed by your doctor. If you miss a dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store Metformin at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

In addition to its desired action, this medication may cause some adverse effects, notably: it may cause headaches; it may cause diarrhea; it may cause gas and bloating; it may cause abdominal discomfort; it may cause nausea and vomiting. Each person may react differently to a treatment. If you think this medication may be causing adverse effects (including those described here, or others), talk to your health care professional. He or she can help you to determine whether or not the medication is the source of the problem.

500 mg
Each white, round, biconvex, coated tablet, imprinted "met" over "500" on the scored side and "P" logo on the other side, contains metformin HCl 500 mg. Nonmedicinal ingredients: colloidal silicon dioxide, croscarmellose sodium, hydroxypropyl methylcellulose, magnesium stearate, microcrystalline cellulose, polyethylene glycol, povidone PVK-90, and pregelatinized starch.

850 mg
Each white, capsule-shaped, biconvex, coated tablet, imprinted "P" logo on one side and "850" on the other side, contains metformin 850 mg. Nonmedicinal ingredients: colloidal silicon dioxide, croscarmellose sodium, hydroxypropyl methylcellulose, magnesium stearate, microcrystalline cellulose, polyethylene glycol, povidone PVK-90, and pregelatinized starch.

Do not take Metformin if you:

• are allergic to metformin or any ingredients of Metformin
• are experiencing or recovering from severe infections, trauma, or surgery
• are pregnant or breast-feeding
• are suffering severe dehydration (have lost a lot of water from your body)
• are undergoing radiologic studies involving use of iodinated contrast materials
• drink large amounts of alcohol in the short term or on a regular basis
• have a history of lactic acidosis
• have acute/chronic metabolic acidosis (too much acid in the blood), diabetic ketoacidosis with or without coma, or history of ketoacidosis with or without coma
• have diseases associated with lack of oxygen to the tissues such as cardio-respiratory insufficiency
• have reduced kidney function
• have severe liver disease
• have Type 1 Diabetes (people with type 1 diabetes should always be using insulin)
• have very poor blood glucose control (these people should not take Metformin as the only antidiabetic agent)

There may be an interaction between metformin and any of the following:

• Acetazolamide
• acetylsalicylic acid (Asa)
• alcohol
• angiotensin converting enzyme inhibitors (ACEIs; Captopril, Enalapril, Ramipril)
• antipsychotics (e.g., Clozapine, Olanzapine, Quetiapine, Risperidone)
• beta 2 agonists (e.g., salbutamol, formoterol, terbutaline)
• birth control pills
• Brinzolamide
• Bupropion
• calcium channel blockers (e.g., Amlodipine, Diltiazem, Nifedipine, Verapamil)
• Cephalexin
• Cimetidine
• corticosteroids (e.g., Dexamethasone, Prednisone)
• Danazol
• decongestants (e.g., phenylephrine, Pseudoephedrine)
• diabetic drugs (e.g., Glyburide, insulin, Repaglinide, Sitagliptin)
• Disopyramide
• diuretics (water pills; e.g., Amiloride, Furosemide, Hydrochlorothiazide)
• dofetilide
• dolutegravir
• estrogens (e.g., conjugated estrogen, Estradiol, ethinyl estradiol)
• Glucagon
• glycopyrrolate
• Hepatitis C antivirals (e.g., dasabuvir, ombitasvir, paritaprevir, ritonavir)
• HIV protease inhibitors (e.g., atazanavir, indinavir, ritonavir, saquinavir)
• iodinated contrast material
• Lamotrigine
• Lanreotide
• mifepristone
• monoamine oxidase inhibitors (M.O.S. e.g., Moclobemide, Phenelzine, Rasagiline, Selegiline, Tranylcypromine)
• nicotinic acid (Niacin)
• Octreotide
• Ondansetron
• Pasireotide
• Pegvisomant
• pentamidine
• Phenytoin
• procainamide
• progestins (e.g., Dienogest, Levonorgestrel, medroxyprogesterone, Norethindrone)
• quinine
• quinolone antibiotics (e.g., ciprofloxacin, Norfloxacin, Ofloxacin)
• selective serotonin reuptake inhibitors (SSRIs; e.g., Citalopram, Fluoxetine, Paroxetine, Sertraline)
• Somatropin
• sulfonamide antibiotics ("sulfas"; e.g., sulfisoxazole, sulfamethoxazole)
• Sunitinib
• Tacrolimus
• testosterone
• Thyroid products
• Topiramate
• Trimethoprim

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with Metformin. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the Nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

Before you begin taking a medication, be sure to inform your doctor of any medical conditions or Allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should take Metformin.

Alcohol intake: Anyone taking metformin should avoid excessive alcohol intake.

Blood sugar control: If you have fever, trauma, infection, or surgery, you may have a temporary loss of blood sugar control. At such times, your doctor may think it is necessary to stop metformin and temporarily inject insulin. Metformin may be started again after the problem is resolved.

Blood sugar monitoring: Monitor your blood sugar regularly at intervals as discussed with your doctor or diabetes educator.

Diabetes complications: The use of metformin (or any other medication used for diabetes) will not prevent the development of complications particular to diabetes mellitus (e.g., Kidney Disease, nerve disease, eye disease).

Diet: Metformin is a treatment to be taken in combination with a proper diet. Metformin is not a substitute for proper diet.

Dye or contrast agents: If you are going to have an X-ray procedure that uses dye or a contrast agent, you may need to stop taking Metformin for a short time. Contact your doctor for instructions.

Kidney problems: Kidney disease or reduced kidney function causes Metformin to build up in the body, causing side effects. If you have kidney problems, your doctor should closely monitor your condition while you are taking metformin, as it may affect kidney function.

Lactic acidosis: Lactic acidosis is a rare but serious problem that occurs due to metformin accumulation (i.e., the body doesn't get rid of it fast enough) during treatment. If you have severe kidney disease you are at higher risk of developing lactic acidosis. Since alcohol may increase the risk of lactic acidosis, do not drink a lot of alcohol over the short- or long-term while taking Metformin. When it does occur (very rarely), it is fatal in 50% of cases. There have been no reports of lactic acidosis in Canada when metformin was used as directed. If you experience symptoms of lactic acidosis (e.g., weakness, tiredness, drowsiness, unusual muscle pain, trouble breathing, stomach pain with nausea, vomiting or diarrhea, feeling cold, dizziness, light-headedness, or slow or irregular heartbeat), stop taking Metformin and get immediate medical attention.

Liver function: Decreased liver function has been linked to lactic acidosis. Metformin is not recommended for people with severely reduced liver function. If you have moderately reduced liver function, discuss with your doctor how Metformin may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Metformin, and whether any special monitoring is needed.

Low blood sugar: Under usual circumstances, low blood sugar does not occur for people who take only metformin. Low blood sugar could occur when not enough food is eaten, especially when strenuous exercise is undertaken at the same time or when large amounts of alcohol have been consumed.

Reduced response: Over a period of time, you may become progressively less responsive to a particular treatment for diabetes because your diabetes worsens. If metformin fails to lower blood sugar to target levels, talk to your doctor. Your doctor may want to stop metformin or recommend another medication.

Surgery: Metformin should be stopped temporarily for surgery (except for minor surgery where food and fluid intake is not restricted). You will be restarted on Metformin once you are eating and drinking and your kidney function has been tested and is normal. Talk to your doctor for specific instructions.

Vitamin B12 levels: Metformin may decrease vitamin B12 levels. Your doctor will monitor your B12 levels with blood tests while you are taking Metformin.

Pregnancy: Metformin should not be used during pregnancy. If you become pregnant while taking Metformin, contact your doctor immediately.

Breast-feeding: Metformin is believed to pass into breast milk. Metformin should not be used if you are breast-feeding.

Children: The safety and effectiveness of Metformin have not been established for children.

Seniors: Kidney function often decreases with age. As a result, seniors may be more likely to experience side effects of Metformin.

This medication is typically used only once a day. However, your pharmacist may have suggested a different schedule that is more appropriate for you. It must be used regularly and continuously to maintain its beneficial effects. Be sure to keep an adequate supply on hand. If this medication is used to treat diabetes, you should monitor your blood sugar levels regularly using the appropriate device. This medication should be swallowed whole. It should not be split, crushed or chewed. You may notice the presence of a whole tablet in your stools. This is only the outer shell; the medication inside has been absorbed. If you forget a dose, take it as soon as you remember -- unless it is almost time for your next dose. In that case, skip the missed dose. Do not double the next dose to catch up. This medication is more effective if taken with food. Always take it with a meal or a snack. Avoid excessive alcohol consumption during treatment.