1. Clinical Overview
A fixed-dose combination (FDC) oral anti-diabetic drug containing a second-generation sulfonylurea (Gliclazide) and a biguanide (Metformin). It is a cornerstone therapy for the management of Type 2 Diabetes Mellitus (T2DM) in Indian patients, particularly those not adequately controlled on monotherapy with either agent. Gliclazide stimulates insulin secretion from pancreatic beta-cells, while Metformin primarily reduces hepatic glucose production and improves insulin sensitivity. This combination provides a synergistic, multi-targeted approach to glycemic control.
| Onset | Duration | Bioavailability |
|---|---|---|
| Gliclazide: 30-60 minutes. Metformin: 1-2 hours. | Gliclazide: Up to 24 hours (modified-release formulations can extend this). Metformin: 12-24 hours. | Gliclazide: ~95-97%. Metformin: ~50-60%. |
2. Mechanism of Action
The combination works via complementary mechanisms. Gliclazide binds to sulfonylurea receptors (SUR1) on pancreatic beta-cell membranes, leading to closure of ATP-sensitive potassium (K-ATP) channels, membrane depolarization, opening of voltage-gated calcium channels, and subsequent exocytosis of insulin. Metformin's primary action is to decrease hepatic gluconeogenesis and glycogenolysis. It also increases peripheral glucose uptake and utilization (insulin sensitization) in muscles and adipose tissue, and may delay intestinal glucose absorption.
3. Indications & Uses
- Type 2 Diabetes Mellitus in adults as an adjunct to diet and exercise when dual therapy is appropriate.
- Patients inadequately controlled on monotherapy with either Gliclazide or Metformin.
4. Dosage & Administration
Adult Dosage: Usually one tablet (Gliclazide 80mg + Metformin 500mg) twice daily, with or just after breakfast and dinner. Dose must be individualized based on glycemic response. Maximum: Two tablets twice daily (i.e., Gliclazide 320mg + Metformin 2000mg per day). Initiation with lower dose (e.g., once daily) is recommended in some patients.
Administration: Take with meals to reduce gastrointestinal side effects from Metformin. Swallow whole with a glass of water; do not crush or chew. Maintain regular meal patterns to avoid hypoglycemia. Dose timing should be consistent with major meals.
5. Side Effects
Common side effects may include:
- Hypoglycemia (more common with Gliclazide)
- Gastrointestinal: Nausea, vomiting, diarrhea, abdominal pain, metallic taste (more common with Metformin, especially at initiation)
- Headache
- Dizziness
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Other Anti-diabetics (Insulin, Thiazolidinediones) | Increased risk of hypoglycemia | Major |
| Beta-blockers (e.g., Propranolol) | Masked hypoglycemic symptoms (tachycardia); may potentiate hypoglycemia | Moderate |
| Alcohol | Increased risk of lactic acidosis (Metformin); potentiation of hypoglycemic effect; disulfiram-like reaction (Gliclazide) | Major |
| Warfarin | Gliclazide may potentiate anticoagulant effect | Moderate |
| CYP2C9 Inhibitors (e.g., Fluconazole, Amiodarone, Sulfinpyrazone) | Increased Gliclazide plasma levels → hypoglycemia risk | Moderate |
| CYP2C9 Inducers (e.g., Rifampicin, Carbamazepine) | Decreased Gliclazide plasma levels → hyperglycemia | Moderate |
| Cationic Drugs (e.g., Cimetidine, Ranitidine, Digoxin, Amiloride) | Competition for renal tubular secretion → increased Metformin levels | Moderate |
| Diuretics (especially Loop and Thiazide) | May cause hyperglycemia; risk of lactic acidosis with Metformin if dehydration occurs | Moderate |
| Corticosteroids (e.g., Prednisolone) | Decreased hypoglycemic effect → hyperglycemia | Major |
| NSAIDs (e.g., Ibuprofen) | May potentiate hypoglycemic effect of sulfonylureas | Moderate |
7. Patient Counselling
- DO take the medicine with meals, as directed by your doctor.
- DO monitor your blood sugar levels regularly.
- DO maintain a regular diet and exercise schedule.
- DO carry a sugar source (glucose tablets, candy) at all times to manage hypoglycemia.
- DO inform all your doctors and surgeons that you are taking this medicine.
- DON'T skip meals after taking the drug.
- DON'T consume alcohol excessively.
- DON'T start, stop, or change the dose of any other medicine without consulting your doctor.
- DON'T take the medicine if you are pregnant, planning pregnancy, or breastfeeding without medical advice.
8. Toxicology & Storage
Overdose: Primarily manifests as HYPOGLYCEMIA: sweating, clammy skin, anxiety, tachycardia, hunger, paresthesia, headache, drowsiness, visual disturbances, coma, and seizures. With massive Metformin overdose, lactic acidosis may occur (non-specific symptoms: malaise, myalgia, respiratory distress, somnolence, abdominal pain, hypothermia, hypotension, bradyarrhythmia).
Storage: Store below 30°C. Protect from light and moisture. Keep the bottle tightly closed. Keep out of reach and sight of children. Do not use after the expiry date printed on the pack.