Glimepiride 1 mg, Metformin 500 mg (SR), Pioglitazone 15 mg Uncoated Bilayered Tablets

Pioglitazone and glimepiride tablets combine 2 antihyperglycemic agents with different mechanisms of action to improve glycemic control in patients with type 2 diabetes: pioglitazone, a member of the thiazolidinedione class, and glimepiride, a member of the sulfonylurea class. Thiazolidinediones are insulin-sensitizing agents that act primarily by enhancing peripheral glucose utilization, whereas sulfonylureas are insulin secretagogues that act primarily by stimulating release of insulin from functioning pancreatic beta cells.

Pioglitazone — Pioglitazone is a thiazolidinedione that depends on the presence of insulin for its mechanism of action. Pioglitazone decreases insulin resistance in the periphery and in the liver resulting in increased insulin-dependent glucose disposal and decreased hepatic glucose output. Pioglitazone is not an insulin secretagogue. Pioglitazone is an agonist for peroxisome proliferator-activated receptor-gamma (PPARγ). PPAR receptors are found in tissues important for insulin action such as adipose tissue, skeletal muscle, and liver. Activation of PPARγ nuclear receptors modulates the transcription of a number of insulin responsive genes involved in the control of glucose and lipid metabolism.

In animal models of diabetes, pioglitazone reduces the hyperglycemia, hyperinsulinemia, and hypertriglyceridemia characteristic of insulin-resistant states such as type 2 diabetes. The metabolic changes produced by pioglitazone result in increased responsiveness of insulin-dependent tissues and are observed in numerous animal models of insulin resistance.

Because pioglitazone enhances the effects of circulating insulin (by decreasing insulin resistance), it does not lower blood glucose in animal models that lack endogenous insulin.

Glimepiride — Glimepiride primarily lowers blood glucose by stimulating the release of insulin from pancreatic beta cells. Sulfonylureas bind to the sulfonylurea receptor in the pancreatic beta cell plasma membrane, leading to closure of the ATP-sensitive potassium channel, thereby stimulating the release of insulin.

Pediatric Patients — No pharmacokinetic studies of pioglitazone and glimepiride tablets were performed in pediatric patients.

Obese Patients — The pharmacokinetics of glimepiride and its metabolites were measured in a single-dose study involving 28 patients with type 2 diabetes who either had normal body weight or were morbidly obese. While the Tmax, CL/F, and Vd/F of glimepiride in the morbidly obese patients were similar to those in the normal weight group, the morbidly obese had lower Cmax and AUC than those of normal body weight. The mean Cmax, AUC0-24, AUC0-∞ values of glimepiride in normal vs. morbidly obese patients were 547 ± 218 ng/mL vs. 410 ± 124 ng/mL, 3210 ± 1030 hours∙ng/mL vs. 2820 ± 1110 hours∙ng/mL and 4000 ± 1320 hours∙ng/mL versus 3280 ± 1360 hours∙ng/mL, respectively.

Drug-Drug Interactions — Coadministration of pioglitazone (45 mg) and a sulfonylurea (5 mg glipizide) administered orally once daily for seven days did not alter the steady-state pharmacokinetics of glipizide. Glimepiride and glipizide have similar metabolic pathways and are mediated by CYP2C9; therefore, drug-drug interaction between pioglitazone and glimepiride is considered unlikely. Specific pharmacokinetic drug interaction studies with pioglitazone and glimepiride tablets have not been performed, although such studies have been conducted with the individual pioglitazone and glimepiride components.

Metformin is a biguanide that improves glucose tolerance in patients with type 2 diabetes, lowering both basal and postprandial plasma glucose. Metformin decreases hepatic glucose production, decreases intestinal absorption of glucose, and improves insulin sensitivity by increasing peripheral glucose uptake and utilization. With metformin therapy, insulin secretion remains unchanged while fasting insulin levels and day-long plasma insulin response may decrease.

Absorption — Following a single oral dose of 1,000 mg (2x500 mg tablets) metformin hydrochloride extended-release tablets after a meal, the time to reach maximum plasma metformin concentration (T max) is achieved at approximately 7 to 8 hours. In both single- and multiple-dose studies in healthy subjects, once daily 1,000 mg (2x500 mg tablets) dosing provides equivalent systemic exposure, as measured by area under the curve (AUC), and up to 35% higher C max, of metformin relative to the immediate-release given as 500 mg twice daily.

At usual clinical doses and dosing schedules of metformin, steady state plasma concentrations of metformin are reached within 24 to 48 hours and are generally <1 mcg/mL.

In a two-way, single-dose, crossover study in healthy volunteers, the 1,000 mg tablet was found to be similar to two 500 mg tablets under fed conditions based on equivalent C max and AUCs for the two formulations.

Single oral doses of metformin hydrochloride extended-release tablets from 500 mg to 2,500 mg resulted in less than proportional increase in both AUC and C max.

Effect of food: Low-fat and high-fat meals increased the systemic exposure (as measured by AUC) from metformin hydrochloride extended-release tablets by about 38% and 73%, respectively, relative to fasting. Both meals prolonged metformin T max by approximately 3 hours but C max was not affected.

Distribution — The apparent volume of distribution (V/F) of metformin following single oral doses of 850 mg metformin HCl averaged 654±358 L. Metformin is negligibly bound to plasma proteins. Metformin partitions into erythrocytes, most likely as a function of time.

Metabolism — Intravenous, single-dose studies in healthy subjects demonstrate that metformin is excreted unchanged in the urine and does not undergo hepatic metabolism (no metabolites have been identified in humans), nor biliary excretion.

Excretion — Renal clearance is approximately 3.5 times greater than creatinine clearance, which indicates that tubular secretion is the major route of metformin elimination. Following oral administration, approximately 90% of the absorbed drug is eliminated via the renal route within the first 24 hours, with a plasma elimination half-life of approximately 6.2 hours. In blood, the elimination half-life is approximately 17.6 hours, suggesting that the erythrocyte mass may be a compartment of distribution.

Renal Impairment — Following a single-dose administration of metformin hydrochloride extended-release tablets 500 mg in subjects with mild and moderate renal impairment, the oral and renal clearance of metformin were decreased by 33% and 50% and 16% and 53%, respectively. Metformin peak and systemic exposure was 27% and 61% greater, respectively in subjects with mild renal impairment and 74% and 2.36-fold greater in subjects with moderate renal impairment as compared to healthy subjects [see Dosage and Administration (2.2), Contraindications (4), and Warnings and Precautions (5.1)].

Hepatic Impairment — No pharmacokinetic studies of metformin hydrochloride extended-release tablets have been conducted in subjects with hepatic impairment [see Warnings and Precautions (5.1) and Use in Specific Populations (8.7)].

Geriatrics — Limited data from controlled pharmacokinetic studies of metformin HCl in healthy elderly subjects suggest that total plasma clearance of metformin is decreased by 35%, the half-life is prolonged by 64% and C max is increased by 76%, compared to healthy young subjects. From these data, it appears that the change in metformin pharmacokinetics with aging is primarily accounted for by a change in renal function [see Dosage and Administration (2) and Warnings and Precautions (5.1)].

Gender — In the pharmacokinetic studies in healthy volunteers, there were no important differences between male and female subjects with respect to metformin AUC and t 1/2. However, C max for metformin was 40% higher in female subjects as compared to males. In controlled clinical studies in patients with type 2 diabetes, the antihyperglycemic effect of metformin HCl tablets was comparable in males and females. The gender differences for C max are unlikely to be clinically important.