Metformin

Overview

What is Metformin? 

Metformin is a prescription medication primarily used to control high blood sugar in people with type 2 diabetes. 

Metformin's active ingredient is metformin hydrochloride. It may also contain inactive ingredients to form the tablet or extended-release tablet. 

Metformin is a biguanide and is composed of two linked guanidine rings. It is synthesized in a laboratory setting and is not derived from any natural sources. 

Global Name

Generic name: Metformin
Brand names:  Glucophage, Metformin ER, Glumetza, Fortamet, Riomet

Usage

What is Metformin used for? 

Metformin has the following effects: 

• Metformin is used to improve blood sugar control in adults and children with type 2 diabetes. In less common cases, it is used for the prevention of type 2 diabetes. 

• Treatment of polycystic ovary syndrome (PCOS). 

• Reducing the risk of cancer in patients with type 2 diabetes, including breast cancer, colon cancer, and prostate cancer. 

• Lowering the risk of cognitive impairment (dementia) and stroke. Some studies indicate that diabetic patients taking metformin experience milder cognitive decline and have lower rates of cognitive impairment and stroke compared to diabetic patients not taking metformin. 

• Delaying ageing, and the onset or progression of chronic diseases, thereby extending lifespan. Preliminary studies suggest that metformin may slow ageing and extend lifespan by improving the body's response to insulin, providing antioxidant effects, and improving vascular health. 

• Metformin can stimulate bone formation and reduce bone resorption, potentially maintaining facial bone density and preventing skin ageing. 

Although preliminary studies suggest that metformin has anti-ageing effects and maintains facial bone density, its specific effectiveness in delaying ageing still requires further research to confirm its concrete impact on combating ageing and even extending lifespan. 

How do you use Metformin? 

Availability:

Metformin is available in tablet, extended-release tablet, and liquid forms. 

Dosage information:

• Adults: Start with 500 mg orally twice a day or 850 mg once a day, with gradual dose increases to reduce gastrointestinal side effects. 
• Children (10 years and older): Initial dose typically 500 mg orally twice a day. 

Suitability: 

• Children: Yes, for those 10 years and older. 
• Adults: Yes. 
• Elderlies: Yes, with consideration for renal function. 
• Pregnancy and Lactation: Consult a healthcare provider; may be used in some cases under medical supervision, generally safe in pregnancy (FDA Category B)  

Is there anyone who can’t take Metformin? 

• Children: Not recommended for children under 10 years. 
• Adults: Those with severe kidney or liver problems should not take it. 
• Elderlies:  Elderly with compromised renal function are at-risk for lactic acidosis therefore use is generally avoided. 
• Allergy to metformin or any other components of the drug.

Warnings and Precautions:

Monitor blood sugar levels regularly, take after meals to reduce gastrointestinal upset, and watch for signs of lactic acidosis, a rare but serious complication. 

Drug and Food/Beverage Interactions: 

Metformin should not be used with iodinated contrast media or with medications that can affect renal function. Can have additive hypoglycemic effect when used with insulin and other anti-diabetes medication. High-fat and high-calorie diet can lower the absorption of metformin from the intestines. Alcohol should be avoided due to the risk of lactic acidosis. 

Metformin Side Effects

Common side effects include gastrointestinal issues such as diarrhea, nausea, and abdominal pain. Lactic acidosis is a severe but rare side effect. 

Metformin Pharmacist Tips and Storage

Storage information:  

• Gradual Introduction: Start Metformin at the lowest dose and gradually increase as directed by your healthcare provider to minimize gastrointestinal side effects. 
• Timing of Doses: Take Metformin with meals to help reduce stomach upset. If you’re on an extended-release formula, remember to take it with your evening meal. 
• Maintain Diet and Exercise: For the best glucose control, maintain a diet low in sugars and refined carbs and follow a regular exercise routine, as advised by your healthcare provider. 
• Understanding Side Effects: If you experience minor side effects, such as gastrointestinal discomfort, these may decrease over time. However, if you experience symptoms like muscle pain, difficulty breathing, stomach pain with nausea, or any unusual symptoms, contact your doctor immediately as these could be signs of lactic acidosis. 
• Missed Dose Protocol: If you miss a dose, take it as soon as you remember unless it’s almost time for your next dose. Do not double up on doses to make up for the missed one. 
• Traveling with Medication: When traveling, keep Metformin in its original container, labeled by the pharmacy, and always carry it in your carry-on baggage. 
• Regular Blood Sugar Testing: Keep track of your blood sugar levels as your doctor has instructed. This will help you determine how well Metformin is working for you. 
• Kidney Function Monitoring: Since Metformin is cleared by the kidneys, it's essential to have your kidney function checked before starting the medication and regularly thereafter. 
• Proper Disposal: Do not flush unused or expired Metformin down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed by bringing it to a take-back program if available. 
• Consult Before Adding Supplements: Some vitamins and herbal supplements may interact with Metformin. Always consult with your healthcare provider before starting any new supplements. 
• Stay Hydrated: Drinking plenty of fluids may help prevent some of the side effects associated with Metformin, such as headaches and dehydration. 

Availability of Metformin

Where is Metformin available in Hong Kong?

Metformin is a prescription-only medication in Hong Kong and is not available over the counter. It can only be dispensed with a valid prescription from a registered doctor. Once prescribed, Metformin can be obtained from hospital and clinic pharmacies as well as registered community pharmacies. Because dosing depends on your kidney function and overall health, a healthcare provider will assess your suitability and determine the appropriate dose before prescribing, and will usually arrange follow-up monitoring.

FAQs

Can Metformin cause weight loss?

Metformin is not a weight-loss drug, but some people experience modest weight loss or weight stabilisation while taking it, partly due to reduced appetite and improved insulin sensitivity. Any weight change varies between individuals.

How long does Metformin take to work?

Metformin begins to lower blood sugar within a couple of days, but it can take up to two weeks to feel its full effect. Your doctor may increase the dose gradually to reduce side effects while improving blood sugar control.

Should I take Metformin with food?

Yes. Metformin is best taken with meals to reduce the chance of stomach upset. If you are on an extended-release formulation, it is usually taken with your evening meal.

What should I do if I miss a dose?

Take the missed dose as soon as you remember, unless it is almost time for your next dose. Do not take a double dose to make up for a missed one.

Is Metformin safe to take during pregnancy?

Metformin may be used during pregnancy in some situations under medical supervision. Consult your healthcare provider before taking it if you are pregnant, planning to become pregnant, or breastfeeding.