Bioequivalence of Related GelShieldⓇ Sustained-release Formulations of Metformin: A Pooled Pharmacokinetic Analysis.

PURPOSE: GlucophageⓇ (Merck Healthcare KGaA, Darmstadt, Germany) is the originator brand of metformin hydrochloride, an oral antidiabetic drug. Metformin is recommended in guidelines as first-line treatment of type 2 diabetes mellitus and increasingly in related insulin-resistant conditions, such as prediabetes and polycystic ovary syndrome. The GelShieldⓇ sustained-release formulation tablet of GlucophageⓇ has been improved from the historic version marketed in 2000. Bioequivalence has been demonstrated stepwise along this evolution; however, a head-to-head evaluation between the initial and the current version is missing. This analysis aims to close this gap and to determine bioequivalence between related originator GelShieldⓇ sustained-release formulations of metformin, GlucophageⓇ (GXR 500 mg), from Europe and the United States. METHODS: Data from seven randomized crossover bioequivalence studies in 361 healthy participants of Asian and non-Asian ethnicity from Europe, the United States, and Asia were considered. All evaluated a single oral dose of 500 mg of the test and reference formulation in healthy male and female participants in fed and fasted state. Bioequivalence was evaluated by means of a combined bridging analysis of available data on the current round tablet from Europe (rGXR EU) and the historic oblong tablet from the United States (oGXR US) in healthy Asian and non-Asian participants under fed and fasting conditions. Bioequivalence between the two formulations was assessed statistically with a mixed effects model for AUC0-t, Cmax, and AUC0-inf. FINDINGS: In all studies, bioequivalence between the respective test and reference formulations of GXR was shown. Statistical analysis of pooled pharmacokinetic data of 2 (primary pooling set) or 3 studies (secondary pooling set) demonstrated bioequivalence between rGXR EU and oGXR US via bridging with oGXR EU. The 90% CI for the geometric mean ratio of all pharmacokinetic parameters was within the bioequivalence range of 0.80 to 1.25. In the primary pooling set, geometric least squares mean ratios in the fed group ranged from 0.9931 (90% CI, 0.9151-1.0778) for AUC0-inf to 1.1344 (90% CI, 1.0711-1.2014) for Cmax; results in the fasted group were similar. The secondary pooling set, which added a study in Asians, confirmed these findings. IMPLICATIONS: Bioequivalence was determined between sustained-release formulations of GlucophageⓇ from Europe and the United States under fasted and fed conditions in healthy men and women, including different ethnicities. The efficacy and safety of GlucophageⓇ XR can be claimed along the evolution from oGXR US, via oGXR EU to rGXR EU, and in several ethnicities and production sites.

Bioequivalence Evaluation in Healthy Volunteers: New Generic Formulations of Sitagliptin and Sitagliptin-Metformin Fixed-Dose Combination Compared with the Originator Products.

INTRODUCTION: Three studies compared the bioequivalence (BE) of new generic tablet formulations of sitagliptin (100 mg; fasting) and the fixed-dose combination (FDC) of sitagliptin/metformin (50/850 mg, 50/1000 mg; both fed) in healthy volunteers with the same tablet strengths of the reference products Januvia and Janumet. METHODS: The study design was open-label, single-dose, randomized with two-way crossover periods. Blood sampling was performed for 72/48 h in the sitagliptin/FDC studies, respectively. Primary pharmacokinetic (PK) parameters for sitagliptin and metformin were area under the plasma concentration-time curve from time 0 to last timepoint of measurable concentration (AUC0-t) and maximum plasma concentration (Cmax). Test (T) and reference (R) formulations proved bioequivalent if 90% confidence interval (CI) of geometric least-squares mean ratio for AUC0-t and Cmax were within BE acceptance range of 80.00-125.00%. Safety evaluations included vital signs, clinical laboratory tests, and adverse events (AEs). RESULTS: Treated/evaluable volunteers for BE per study were: 30/28 (sitagliptin 100 mg), 26/25 (FDC 50/850 mg), and 26/24 (FDC 50/1000 mg). The 90% CI of the geometric means of T/R ratios for primary PK parameters were within predefined BE limits: CI for AUC0-t and Cmax were 95.83-100.37% and 91.85-109.56% (sitagliptin 100 mg); 100.84-103.69% and 93.44-105.10% (FDC 50/850 mg), and 101.26-105.20% and 98.71-112.89% (FDC 50/1000 mg); respective values for metformin were 94.23-101.89% and 91.66-99.38% (FDC 50/850 mg) and 98.45-104.89% and 96.79-105.62% (FDC 50/1000 mg). All AEs were nonserious, transient, and mostly mild. Safety evaluations did not reveal any relevant difference between T and R formulations. CONCLUSIONS: The new generic tablet formulations of sitagliptin 100 mg and the FDCs sitagliptin/metformin 50/850 mg and 50/1000 mg demonstrated bioequivalence to originator reference products. Therefore, the new products are expected to provide efficacy and tolerability similar to those of the reference products in the treatment of patients with type 2 diabetes (T2D). TRIAL REGISTRATION: EudraCT EU Clinical Trials Registry (2014-005437-31); ClinicalTrials.gov Registry (NCT05549570 and NCT05549583, both retrospectively registered on 20 September 2022).

Bioequivalence Studies of New Generic Formulations of Vildagliptin and Fixed-Drug Combination of Vildagliptin and Metformin Versus Respective Originator Products in Healthy Volunteers.

INTRODUCTION: Vildagliptin and metformin are two well-established oral antidiabetics with a complementary mechanism of action. Two new generic products, vildagliptin and its fixed-drug combination (FDC) with metformin, were tested for bioequivalence versus the approved originator reference products (Galvus® and Eucreas®). METHODS: Three randomized studies with two-treatment, two-period, two-sequence crossover design were conducted in healthy adults. One study evaluated vildagliptin 50 mg tablets as single dose under fasting conditions. Vildagliptin-metformin FDC tablet strengths of 50/850 mg and 50/1000 mg were evaluated in separate studies as single dose under fed conditions, given 30 min after a standardized high-fat, high-calorie breakfast following 10 h overnight fasting. Blood samples for analysis were collected until 24 h after dosing in each study period. Bioequivalence between test (T) and reference (R) products required 90% confidence interval (CIs) for the geometric least square (LS) mean T/R ratio to be within 80-125% for the pharmacokinetic parameters, maximum plasma concentration (Cmax), and area under the curve (AUC0-t). RESULTS: The 90% CIs of geometric LS means of T/R ratio for Cmax and AUC0-t with vildagliptin tablets of 50 mg were 92.22-103.94% and 99.00-102.66%, respectively; corresponding results with FDC tablets for 50/850 mg tablets were 94.81-115.41% and 95.28-106.00% for vildagliptin and 90.87-101.18% and 90.56-100.09% for metformin; for 50/1000 mg tablets Cmax and AUC0-t were 105.56-122.30% and 98.30-107.55%, respectively, for vildagliptin and 92.14-103.73% and 94.60-101.81%, respectively, for metformin. Other parameters such as AUC0-∞, time to maximum concentration (Tmax), and terminal half-life (t1/2) were comparable between test and reference products. Adverse events (AEs), mainly vomiting, were reported without relevant difference between test and reference products in each study. AEs were generally mild and transient. No severe or serious AEs occurred. CONCLUSIONS: The new generic drug products of vildagliptin and the FDCs of vildagliptin and metformin demonstrated bioequivalence to the approved originator products and are therefore expected to provide similar therapeutic effects.

Effects of etoricoxib on the pharmacokinetics of phenytoin.

Etoricoxib is presently the most commonly prescribed cyclooxygenase-2 (Cox-2) inhibitor for chronic pain and inflammatory conditions. In clinical practice, phenytoin and etoricoxib are used in chronic conditions of generalized seizure with concomitant chronic pain. Hence, there are chances of drug-drug interaction because modulations of isoenzymes involved in metabolism CYP2C9/10 and CYP2C19 which partially inhibited by etoricoxib. It is important to maintain the therapeutic level of phenytoin in plasma for effective control of seizure. So, the aim of the study was to determine the effect of etoricoxib on the pharmacokinetics of phenytoin in rabbits. In a parallel design study, phenytoin (30 mg/kg/day) was given daily for seven days. On day 7, blood samples were taken at various time intervals between 0-24 h. In etoricoxib group, phenytoin was administered for seven days as above. On day 8, etoricoxib (5.6 mg/kg) along with phenytoin (30 mg/kg/day) was administered and blood samples were drawn as above. Plasma phenytoin levels were assayed by HPLC and pharmacokinetic parameters were calculated. In etoricoxib group, there was a decrease in t(1/2)a phenytoin and t(1/2)el decreased significantly as compared to phenytoin group. Significant changes were observed in the pharmacokinetic parameters in etoricoxib-treated group. These results suggest that etoricoxib alters the pharmacokinetics of phenytoin. Confirmation of these results in human studies will warrant changes in phenytoin dose or frequency when etoricoxib is co-administered with it.