💊 Metformin (Metformin)
Metformin is used with diet and exercise to improve blood sugar control in adults and children 10 years and older with type 2 diabetes mellitus. It is taken by mouth and the extended-release tablets must be swallowed whole. It carries a boxed warning for lactic acidosis.
In Arabic: ميتفورمين (ميتفورمين هيدروكلوريد - أقراص ممتدة المفعول)
✅ What it is used for
- Adjunct to diet and exercise to improve glycemic control in adults and pediatric patients 10 years of age and older with type 2 diabetes mellitus
🧪 Active ingredient
Metformin hydrochloride: decreases hepatic glucose production, decreases intestinal glucose absorption, and improves insulin sensitivity by increasing peripheral glucose uptake and utilization. Insulin secretion remains unchanged.
🌿 Benefits
- Improves glucose tolerance, lowering both basal and postprandial plasma glucose in type 2 diabetes
- Improves insulin sensitivity without increasing insulin secretion
📝 How to use
- Your dose is set by your doctor or pharmacist based on your condition, response and kidney function; do not change it yourself
- Swallow tablets whole; never crush, cut or chew
- Per the label, the dose is usually taken once daily with the evening meal
- Kidney function is assessed before starting and periodically afterwards
- Metformin may need to be stopped at the time of, or before, iodinated contrast imaging procedures; ask your doctor
💊 Dosage forms
- Extended-release tablets 500 mg: white to off-white, uncoated, modified capsule-shaped, debossed "G7" on one side
⚠️ Common side effects
- Diarrhea
- Nausea/vomiting
- Flatulence
- Asthenia (weakness)
- Indigestion
- Abdominal discomfort
- Headache
- Also reported in clinical trials: constipation, abdominal distention, dizziness, upper respiratory infection, taste disturbance
🚨 Serious — seek medical help
- Lactic acidosis: nonspecific symptoms such as malaise, muscle pain, abdominal pain, breathing difficulty, unusual sleepiness; hypotension and resistant slow heart rhythms can occur with severe acidosis. Stop the drug and seek hospital care immediately
- Vitamin B12 deficiency
- Hypoglycemia when used with insulin or insulin secretagogues
- Liver injury (cholestatic, hepatocellular, mixed) reported postmarketing
⛔ Do not use if
- Severe renal impairment (eGFR below 30 mL/min/1.73 m²)
- Hypersensitivity to metformin
- Acute or chronic metabolic acidosis, including diabetic ketoacidosis, with or without coma
❗ Warnings & precautions
- Boxed warning: lactic acidosis, which has been fatal in postmarketing cases
- Risk factors: renal impairment, certain concomitant drugs (e.g., topiramate), age 65 or older, radiological studies with contrast, surgery and other procedures, hypoxic states (e.g., acute congestive heart failure), excessive alcohol intake, hepatic impairment
- Initiation not recommended if eGFR is 30 to 45; reassess benefit/risk if eGFR falls below 45; discontinue if below 30
- Avoid use in patients with hepatic impairment
- May lower vitamin B12: measure hematological parameters annually and vitamin B12 at 2 to 3 year intervals
- Avoid excessive alcohol intake during treatment
🔄 Drug interactions
- Carbonic anhydrase inhibitors (topiramate, zonisamide, acetazolamide, dichlorphenamide): may increase lactic acidosis risk; consider more frequent monitoring
- Drugs that reduce metformin clearance (ranolazine, vandetanib, dolutegravir, cimetidine): may increase metformin exposure and lactic acidosis risk
- Alcohol: potentiates metformin's effect on lactate metabolism
- Insulin or insulin secretagogues (e.g., sulfonylureas): may increase hypoglycemia risk; lower doses may be needed
- Drugs that tend to produce hyperglycemia may cause loss of glycemic control; observe closely
🤰 Pregnancy
Limited data are not sufficient to determine a drug-associated risk of major birth defects or miscarriage; published studies have not reported a clear association. Poorly controlled diabetes in pregnancy carries risks to mother and fetus. Premenopausal women should be advised of the potential for unintended pregnancy. Consult your doctor.
🍼 Breastfeeding
The label text provided does not include breastfeeding information; consult your doctor or pharmacist.
🧒 Children
Indicated for pediatric patients 10 years of age and older with type 2 diabetes mellitus, under medical supervision.
👴 Older adults
Renal function should be assessed more frequently in elderly patients; age 65 or older is a risk factor for lactic acidosis.
🌡️ Storage
Store at 20° to 25°C (68° to 77°F); excursions permitted between 15° to 30°C (59° to 86°F). Dispense in a light-resistant container.
⏰ Missed dose
If a dose is missed, do not take two doses on the same day; resume your usual dose with the next scheduled dose.
🆘 Overdose
In case of overdose, contact the Poison Help line (US: 1-800-222-1222) or seek medical care immediately. Lactic acidosis was reported in about 32% of overdose cases and hypoglycemia in about 10% (no causal association established). Hemodialysis may help remove accumulated drug.
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Mechanism of action
Decreases hepatic glucose production, decreases intestinal glucose absorption, and improves insulin sensitivity via increased peripheral glucose uptake and utilization; insulin secretion is unchanged. After a single dose of the extended-release tablet, Cmax occurs at a median of 7 hours (range 4–8); peak plasma levels are ~20% lower than the immediate-release tablet with comparable AUC.
Labeled dosing
Adults and pediatric patients ≥10 years: start 500 mg once daily with the evening meal; increase by 500 mg weekly based on glycemic control and tolerability, up to 2,000 mg once daily. If control is not achieved, consider 1,000 mg twice daily. Switching from immediate-release is at the same total daily dose. Patients needing more than 2,000 mg daily may switch to immediate-release tablets up to a maximum of 2,550 mg daily. Dosing is determined by the prescriber.
- Assess eGFR before initiation and periodically; contraindicated if eGFR <30; initiation not recommended at eGFR 30–45; reassess benefit/risk if eGFR falls below 45
- May need to be discontinued at or before iodinated contrast imaging procedures
- If lactic acidosis is suspected: discontinue immediately, institute supportive measures in hospital; prompt hemodialysis recommended (clearance up to 170 mL/min)
- Monitor vitamin B12 and hematological parameters; consider lower insulin/secretagogue doses to avoid hypoglycemia
🎓 Key points for students
- Drug class: biguanide antihyperglycemic
- Most serious effect: lactic acidosis (lactate >5 mmol/L, anion gap acidosis, raised lactate/pyruvate ratio, plasma metformin generally >5 mcg/mL)
- Metformin decreases hepatic lactate uptake, raising blood lactate
- Key contraindications: eGFR <30, hypersensitivity, metabolic acidosis
- Common adverse effects are gastrointestinal (diarrhea, nausea/vomiting, flatulence)
- Monitor vitamin B12
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What is metformin used for?
To improve blood sugar control in adults and children 10 years and older with type 2 diabetes, together with diet and exercise.
How should I take the extended-release tablets?
Swallow them whole without crushing, cutting or chewing, usually with the evening meal as directed by your doctor.
What are the most common side effects?
Diarrhea, nausea/vomiting, flatulence, weakness, indigestion, abdominal discomfort and headache.
What are the most serious warning signs?
Malaise, muscle pain, abdominal pain, breathing difficulty or unusual sleepiness may indicate lactic acidosis; stop the drug and seek medical care immediately.
Can I drink alcohol while taking metformin?
Avoid excessive alcohol, as it potentiates metformin's effect on lactate metabolism.
What if I miss a dose?
Do not take two doses on the same day; resume your usual dose at the next scheduled time.
⚕️ For education only — not a substitute for advice from your doctor or pharmacist. Do not start or stop any medicine without advice. Source: official FDA drug label via openFDA (2026-09), simplified. Updated: 2026-11-10.