Glucophage SR
In brief
- Glucophage SR is a prescription-only medicine (POM) in the UK, supplied by pharmacies against a valid prescription.
- This drug treats type 2 diabetes by decreasing liver glucose production, reducing intestinal sugar absorption, and improving insulin sensitivity, as classified under ATC code A10BA02 for biguanides.
- The usual dosage starts at 500 mg once daily (with evening meal), titrated weekly by 500 mg to a maximum of 2000 mg/day based on tolerance and glycaemic response.
- It is administered orally as extended-release tablets, designed for once-daily intake without crushing or splitting.
- Onset begins within hours, but full therapeutic effects on blood sugar control may take 1–2 weeks as steady-state concentrations are achieved.
- The sustained-release formulation provides 24-hour glycaemic control with stable plasma concentrations, allowing once-daily dosing.
- Avoid alcohol consumption, as it heightens the risk of lactic acidosis—a potentially fatal side effect—particularly due to metformin’s metabolism.
- The most common side effects are gastrointestinal (nausea, diarrhoea, abdominal pain), which are typically mild and transient, improving with gradual dose titration.
- Would you like to try Glucophage SR without a prescription?
Basic Glucophage SR information
| INN | Metformin hydrochloride |
| UK brand names | Glucophage SR |
| ATC Code | A10BA02 |
| Form & strength | Prolonged-release tablets (500 mg, 750 mg, 1000 mg) |
| Manufacturer | Merck |
| Registration status | Licensed by the MHRA |
| Classification | Prescription-only medicine (POM) |
Glucophage SR contains the active ingredient metformin hydrochloride, formulated as prolonged-release tablets available in 500 mg, 750 mg and 1000 mg strengths. These sustained-release tablets are available in blister packs within cardboard boxes, typically containing 28, 56, or 84 tablets. As a prescription medicine, Glucophage SR can only be obtained through UK pharmacies with a valid prescription following consultation with a healthcare professional. Its MHRA approval confirms its safety and efficacy when used appropriately for managing diabetes. The medication carries POM classification across all healthcare settings in the United Kingdom.
Mechanism of action and pharmacodynamics
Glucophage SR works through dual mechanisms to regulate blood sugar levels without increasing insulin production:
- Reduces hepatic glucose production: Metformin decreases gluconeogenesis (new glucose formation) in liver cells
- Enhances insulin sensitivity: Improves peripheral glucose uptake and utilisation in muscle and fat tissue
Unlike immediate-release formulations, Glucophage SR tablets feature specialised slow-release technology. Hydrophilic polymer matrices in the tablet core gradually absorb water, swelling to form a gel barrier that controls metformin dissolution over 8-10 hours. This extended-release design modulates drug delivery, maintaining steadier plasma concentrations while lowering peak drug levels. Pharmacodynamic effects include suppressed fasting and post-meal glucose values primarily through AMPK activation pathways, with negligible hypoglycaemia risk versus insulin secretagogues.
Approved indications and off-label use
Glucophage SR is licensed in the UK for type 2 diabetes management alongside diet and exercise. Within NHS diabetes pathways, it serves as first-line therapy both as monotherapy and in combination regimens.
Under specialist guidance, evidence supports several off-label applications:
- Polycystic ovary syndrome (PCOS) – improves insulin resistance and ovulation frequency
- Prediabetes management – reduces progression to diabetes in high-risk individuals
- Antipsychotic-induced weight gain mitigation
Important UK-specific protocols exist for:
- Elderly patients: Intensive renal monitoring required before initiation
- Pregnancy: Continued under specialist supervision only
- Adolescents: Typically reserved for obesity-related insulin resistance cases
Prescribing follows practitioners’ clinical judgement after evaluating benefit-risk profiles through NHS diabetes teams.
Standard dosage protocols
| Condition | Initial dose | Maintenance dose | Timing |
|---|---|---|---|
| Type 2 diabetes | 500mg once daily | 1500mg-2000mg maximum once daily | With evening meal |
| PCOS | 500mg once daily | 1000mg-1500mg once daily | With a meal |
Titration follows standardised UK protocols: Doses increase incrementally at 500mg intervals weekly based on tolerance and HbA1c response. Dose adjustments become necessary when renal impairment exists:
- eGFR 45-59 mL/min: Maximum 2000 mg daily
- eGFR 30-44 mL/min: Maximum 1000 mg daily
- eGFR under 30 mL/min: Contraindicated
Tablets must be swallowed whole with fluid during meals, never crushed or split. Glucophage SR is usually taken once daily with the evening meal. Consistently taking Glucophage SR with food minimises gastrointestinal side effects.
Contraindications & safety warnings
Glucophage SR carries several important safety restrictions. Most critically, this medication is absolutely contraindicated for patients with renal impairment (eGFR below 30 mL/min/1.73m²) or those experiencing metabolic acidosis conditions like diabetic ketoacidosis. It should also not be used in patients with severe liver disease, alcoholism, or conditions predisposing to tissue hypoxia like heart failure.
Lactic acidosis is a rare but life-threatening complication requiring urgent hospital treatment. Patients should know its early warning signs: unexplained muscle pain, rapid breathing, extreme fatigue, or abdominal discomfort, especially during heatwaves when dehydration risks increase.
Common side effects, especially at the start of treatment, are mainly gastrointestinal and include:
- Nausea
- Diarrhoea
- Abdominal discomfort
Other effects include a metallic taste and, with long-term use, vitamin B12 deficiency. Most GI symptoms diminish within weeks when taken correctly with evening meals. Alcohol avoidance remains crucial due to heightened lactate production risks.
Therapeutic alternatives comparison
Glucophage SR compares distinctly against other UK diabetes medications:
| Medication (formulation) | Hypoglycaemia risk | NICE recommendation |
|---|---|---|
| Glucophage SR (prolonged release) | Low | First-line monotherapy |
| Gliclazide (immediate release) | High | Second-line option |
| Dapagliflozin (SGLT2 inhibitor) | Low | Combination therapy |
| Insulin glargine | High | Advanced treatment |
As NICE guidelines emphasise, metformin remains first-line therapy (modified-release if the standard form is not tolerated) due to favourable cardiovascular safety and minimal hypoglycaemia risk. Gliclazide becomes appropriate when metformin isn’t tolerated but carries weight gain and hypos risks. Newer agents like SGLT2 inhibitors (dapagliflozin) bring specific kidney and heart benefits in complex cases requiring multidisciplinary diabetes team management.
Common Glucophage SR questions
Patients managing diabetes with Glucophage SR often have specific questions relevant to daily life in the UK. Here are answers to some frequent queries based on NHS guidance and Diabetes UK resources:
Can I take Glucophage SR during Ramadan?
Does metformin SR cause weight gain?
What should I do if I miss a dose of Glucophage SR?
Is it okay to drink alcohol with Glucophage SR?
Guidelines for taking and storing Glucophage SR
Using Glucophage SR correctly maximises its effectiveness and minimises potential side effects. Follow these practical NHS-aligned guidelines:
- Taking your dose: Always swallow Glucophage SR tablets whole with a drink of water. Never crush or chew them – this damages the extended-release mechanism, potentially releasing all the medicine at once and increasing side effects. Take your daily dose with or just after your evening meal to reduce gastrointestinal upset like nausea or stomach ache.
- Lifestyle factors: Avoid excessive alcohol consumption. Be mindful of your hydration, especially during hot weather or exercise, as dehydration can affect kidney function. Regular physical activity complements the medicine’s effect on blood sugar control.
- Storage: Keep Glucophage SR in its original blister pack or container. Store it below 25°C, in a cool, dry place. Keep it out of sight and reach of children. Avoid storing it in bathrooms or near sinks due to moisture. Discard any tablets that are discoloured, damaged, or look different from usual.
- Avoiding common mistakes: Skipping doses regularly makes blood sugar control much harder. Doubling up a dose because you forgot earlier significantly increases the chance of nausea, diarrhoea, and rarely, more serious issues. Stick to your prescribed schedule.
Glucophage SR drug interactions
While generally well-tolerated, Glucophage SR (metformin SR) can interact with certain other medicines. Always inform your doctor and pharmacist about everything you take. Some significant interactions include:
High-risk interactions
| Interacting substance | Risk level | Management |
|---|---|---|
| Contrast dye (iodinated) used in X-ray/CT scans | High | Must pause Glucophage SR at the time of or before the scan and not restart until at least 48 hours afterwards, once kidney function is confirmed stable |
Moderate risk interactions
| Beta-blockers (e.g., propranolol, atenolol for blood pressure/angina) | Moderate | Can sometimes mask low blood sugar symptoms and potentially affect glucose control; need careful monitoring |
| Diuretics (‘water tablets’ like furosemide or bendroflumethiazide) | Moderate | Can affect kidney function and fluid balance, increasing risks; kidney function checks are essential |
Low risk interactions
| ACE inhibitors (e.g., ramipril, lisinopril for blood pressure/heart failure) | Low | No specific metformin dose adjustment usually required |
Always discuss potential drug interactions with your GP or pharmacist before taking Glucophage SR with other medications, especially before scans with iodinated contrast dye.
