Glimepiride + Metformin + Pioglitazone Tablets

Mechanism

Pioglitazone enhances sensitivity towards insulin, increases insulin-dependent glucose disposal, and improves impaired glucose homeostasis. In patients with type 2 diabetes mellitus, these effects result in lower plasma glucose concentrations, lower plasma insulin concentrations, and lower HbA1c values. Pioglitazone is a selective peroxisome proliferator-activated receptor-gamma (PPARγ) agonist in target tissues for insulin action such as adipose tissue, skeletal muscle, and liver. Activation of PPARγ increases the transcription of insulin-responsive genes involved in the control of glucose and lipid production, transport, and utilization. Through this mechanism, pioglitazone shows dual nature and synergistic effect by enhancing tissue sensitivity to insulin and reduces the hepatic production of glucose (i.e. gluconeogenesis) - insulin resistance associated with type 2 diabetes mellitus is therefore improved without an increase in insulin secretion by pancreatic beta cells.
Pioglitazone is well orally absorbed and peak plasma concentration is observed with 2 hours of administration. Presence of food can delay the Tmax. Volume of distribution of pioglitazone is found to be 0.63 ± 0.41 L/kg and about 99% bound to plasma protein. It is mainly metabolised by two process; hydroxylation and oxidation. Majorly it is excreted unchanged in bile or feces and small amount is excreted in urine.

Metformin belongs to the class of biguanids and used in the management of type 2 diabetes mellitus. Metformin is the insulin sensitizer and reduces insulin resistance. Metformin is beneficial in obese patients. Metformin prevents the hepatic glucose production, increases the intestinal absorption of the glucose and inhibit peripheral utilization of the glucose When administered orally, it half absorbed through intestine. Presence of food decreases the absorption of metformin. When 800mg of metformin was administered, the volume of distribution was found to be 654 ± 358 L and is negligibly bound to plasma protein. Metformin is excreted in unchanged form mainly in urine and the half-life is 17.6 hours.

Glimepiride stimulates the beta cells in pancreas to secrete insulin and improves the sensitivity of peripheral tissues to insulin to increase peripheral glucose uptake, thus reducing plasma blood glucose levels and glycated hemoglobin (HbA1C) levels. ATP-sensitive potassium channels in pancreatic beta cells play a role as essential metabolic sensors. When these channels are open, leading to K+ efflux from the cell, membrane hyperpolarization, and suppression of insulin secretion. Glimepiride inhibits the ATP-sensitive potassium channel by binding non-specifically to the B sites of both sulfonylurea receptor-1 (SUR1) and sulfonylurea receptor-2A (SUR2A) subunits as well as the A site of SUR1 subunit of the channel and blocks the influx of potassium ultimately promote insulin secretion from the beta cell.
Glimepiride is completely absorbed through GIT and the volume of distribution was 8.8 L (113 mL/kg). The plasma protein of glimepiride was 99.5% and is mainly metabolised in liver by family of CYP enzymes. It is mainly excreted in urine and the half-life is 5 to 8 hours.

Pharmacokinetics

• Absorption: Metformin SR — gradual release; Pioglitazone — well absorbed; Glimepiride — rapid absorption
• Distribution: Metformin — not protein bound; Pioglitazone — highly protein bound; Glimepiride — highly protein bound
• Metabolism: Metformin — not metabolized; Pioglitazone — hepatic metabolism via CYP2C8; Glimepiride — hepatic metabolism
• Elimination: Metformin — renal excretion unchanged; Pioglitazone — biliary and renal excretion; Glimepiride — renal and biliary excretion
• Half-life: Metformin ≈ 6 hours; Pioglitazone ≈ 5–8 hours; Glimepiride ≈ 5–9 hours

Side Effects

• Hypoglycemia (Glimepiride)
• Weight gain (Pioglitazone)
• Edema
• Nausea
• Diarrhea
• Rare: lactic acidosis, severe hypoglycemia

Contraindication

• Hypersensitivity to Metformin, Pioglitazone, Glimepiride, or excipients
• Renal impairment (eGFR < 30 mL/min/1.73m²)
• Hepatic impairment
• Congestive heart failure (NYHA Class III/IV) — contraindicated with Pioglitazone
• Alcoholism
• Conditions predisposing to lactic acidosis

Interaction

• Alcohol — increases risk of lactic acidosis with Metformin
• Beta-blockers — may mask hypoglycemia symptoms
• CYP2C8 inhibitors (e.g., gemfibrozil) — increase Pioglitazone levels
• Other antidiabetic agents — additive hypoglycemic effect

Warning and Precautions

• Monitor renal function before and during therapy
• Discontinue if lactic acidosis is suspected
• Use cautiously in elderly patients
• Monitor liver function periodically with Pioglitazone
• Monitor blood glucose