Towards Single-Tablet Therapy for Type 2 Diabetes Mellitus

Oral Antidiabetic Drugs: Bioavailability Assessment of Fixed-Dose Combination Tablets of Pioglitazone and Metformin. Effect of Body Weight, Gender, and Race on Systemic Exposures of Each Drug

Bioavailability of pioglitazone and metformin, in 2 dose strengths, given either as a fixed-dose combination tablet or as coadministration of commercial tablets (coad), was studied in young healthy subjects in 2 separate studies. In study I (n = 63), single oral doses of 15-mg pioglitazone/500-mg metformin fixed-dose combination tablets or equivalent doses of commercial tablets were administered, in a fasting state, in an open-label, randomized, crossover study with a 7-day washout period between treatments. Study II (n = 61) was similar in design to study I, except the 15/850-mg fixed-dose combination tablet and coad treatments were evaluated. Least squares mean (fixed-dose combination/coad) ratios and 90% confidence intervals of the ratios for the 15/500-mg dose strength for the maximum observed serum concentration (Cmax) and area under the serum concentration-time curve from time 0 to infinity (AUC(infinity)) were 0.95 (0.86-1.05) and 1.02 (0.98-1.08), respectively, for pioglitazone and 0.99 (0.95-1.03) and 1.03 (0.98-1.08), respectively, for metformin. Bioequivalency for pioglitazone and metformin between fixed-dose combination tablets and coad treatments was met for both strengths of fixed-dose combination tablets. In a post hoc meta-analysis of combined data from the 2 studies (n = 124), there was considerable overlapping in AUC(infinity) values between gender and race (Caucasians, Blacks, and Hispanics), making neither gender- nor racial-based dosing of pioglitazone or metformin necessary.

Replicate Study Design in Bioequivalency Assessment, Pros and Cons: Bioavailabilities of the Antidiabetic Drugs Pioglitazone and Glimepiride Present in a Fixed-Dose Combination Formulation

An open-label, randomized, 2-sequence, 4-period crossover (7-day washout period between treatment), replicate design study was conducted in 37 healthy subjects to assess intersubject and intrasubject variabilities in the peak (Cmax) and total (AUC) exposures to 2 oral antidiabetic drugs, pioglitazone and glimepiride, after single doses of 30 mg pioglitazone and 4 mg glimepiride, given under fasted state, as commercial tablets coadministered or as a single fixed-dose combination tablet. Variabilities for AUC(infinity) for coadministered and fixed-dose combination treatments were similar: 16% to 19% (intra) and 23% to 25% (inter) for pioglitazone and 18% to 19% (intra) and 29% to 30% for glimepiride (inter, excluding 1 poor metabolizer). Fixed-dose combination/coadministered least squares mean ratios of >or=0.86 and the 90% confidence intervals of these ratios for pioglitazone and glimepiride of between 0.80 and 1.25 for Cmax, AUC(lqc), and AUC(infinity) met the bioequivalency standards. Gender analysis showed that women showed mean of 16% and 30% higher exposure than men for glimepiride (excluding 1 poor metabolizer) and pioglitazone, respectively. There was considerable overlapping in the AUC(infinity) values, making gender-dependent dosing unnecessary. Patients taking pioglitazone and glimepiride as cotherapy may replace their medication with a single fixed-dose combination tablet containing these 2 oral antidiabetic drugs.

Pioglitazone plus glimepiride: a promising alternative in metabolic control

Current approaches to pharmacotherapy of type 2 diabetes focus on two key aspects of hyperglycaemia - insulin secretory dysfunction and insulin resistance. Combining drugs that target both these defects via different mechanisms of action improves long-term glycaemic control and offers a number of additional benefits. A fixed-dose combination of pioglitazone and glimepiride in a single tablet is now available in the US (Duetact(TM)). Both pioglitazone and glimepiride are glucose-lowering agents with distinct mechanisms of action. Pioglitazone is a potent and selective peroxisome proliferator-activated receptor-gamma agonist that improves whole-body insulin sensitivity and augments hepatic glucose uptake. On the other hand, glimepiride acts by releasing insulin from pancreatic beta-cells and improves both first and second phases of insulin secretion. These two therapies have been shown to act synergistically to treat type 2 diabetes - glimepiride therapy achieves rapid reductions in glycated haemaglobin (HbA(1c)), whereas pioglitazone sustains glycaemic control in the longer term. Furthermore, pioglitazone and glimepiride affect a number of pleiotropic markers. In particular, pioglitazone has beneficial effects on the atherogenic diabetic dyslipidaemia that are greater than those seen with rosiglitazone and other oral glucose-lowering agents. This advantage is also seen when comparing pioglitazone and rosiglitazone in combination with glimepiride. In addition, pioglitazone also improves a number of atherosclerotic risk markers that appear to translate into clinical benefits on macrovascular outcomes. Glimepiride may also improve several atherosclerotic risk markers and lipoproteins. This review discusses the potential benefits of combining pioglitazone plus glimepiride on patient compliance, targeting the dual effects of insulin resistance and beta-cell dysfunction and affecting a number of metabolic and cardiovascular parameters.

Oral antidiabetic drugs: effect of food on absorption of pioglitazone and metformin from a fixed-dose combination tablet

An open-label, randomized, crossover study involving 28 healthy subjects was conducted to compare the peak (Cmax) and total (AUC(lqc), AUC(infinity)) exposures to pioglitazone and metformin after single-dose administration of a fixed-dose combination tablet containing 15 mg of pioglitazone plus 850 mg metformin when given under fasted versus fed states, with a washout period of 7 days between treatments. Two different fixed-dose combination formulations (bilayer and pioglitazone-micronized fixed-dose combination tablets) were tested. The pioglitazone-micronized fixed-dose combination formulation was selected for clinical development and regulatory approval; the present study describes food effect results with this formulation. For pioglitazone, least squares mean ratios (fed/fasted) and the 90% confidence intervals of these ratios were 1.05 (0.93-1.18) for Cmax, 1.13 (1.02-1.25) for AUC(lqc), and 1.11 (1.01-1.22) for AUC(infinity). For metformin, these values were 0.72 (0.65-0.79) for Cmax, 0.87 (0.81-0.94) for AUC(lqc), and 0.87 (0.81-0.94) for AUC(infinity). Dosing with food resulted in median prolongation of tmax values by 1.5 hours for metformin and 2.0 hours for pioglitazone. Because bioequivalency criteria were met (fed/fasted 90% confidence interval between 0.80 and 1.25) for both pioglitazone and metformin AUC, fixed-dose combination tablets can be taken with or without food, but to minimize gastrointestinal adverse effects of metformin, the fixed-dose combination tablets are recommended to be taken with food.