Effect of calcium supplementation on reversing metformin-based inhibition of vitamin B12 bioavailability in healthy adults using a [13C] cyanocobalamin tracer - A pilot study.

BACKGROUND & AIMS: Metformin is a widely prescribed first line drug for the treatment of type 2 diabetes mellitus (DM). Studies have shown that the use of metformin is often associated with a decrease in vitamin B12 (B12) levels in patients with DM. Few studies have shown that this effect could be mitigated with calcium supplementation. In the present study, we quantified the effect of metformin, and metformin co-administered with calcium on B12 absorption using a novel stable isotope [13C] cyanocobalamin tracer. METHODS: A pilot crossover study was conducted to estimate the bioavailability of B12 in healthy subjects, using [13C] cyanocobalamin as a tracer. In the study, [13C] cyanocobalamin was administered orally to the participants followed by hourly venous sampling to measure the concentration of the tracer and estimate bioavailability. This protocol was followed for three experiment days, each separated by a one month wash out period. As part of the study, all participants received the tracer alone for the control day (C), metformin 850 mg along with the tracer for the metformin day (M) and metformin 850 mg with calcium 500 mg and the tracer for the metformin calcium day (MC). RESULTS: Seven participants completed all three experiment days. The mean B12 bioavailability (±SD, n = 7) was 42.6 ± 10.2% for the control day (C), 30.8 ± 15.3% for the metformin day (M) and 46.4 ± 8.6% for the metformin-calcium day (MC). Repeated measures ANOVA was done and the pairwise comparison showed a significant difference in the B12 bioavailability between control and metformin day (C vs M p = 0.010), and between the metformin and metformin with calcium day (M vs MC p = 0.003). CONCLUSION: B12 bioavailability reduced significantly from baseline (C) when metformin (M) was administered and this reduction was reversed when calcium was co-administered (MC) in healthy participants. In patients using metformin, calcium supplementation as a strategy to prevent B12 deficiency needs to be further studied.

Factors contributing to variability in metformin concentration in polycystic ovary syndrome.

AIM: To investigate the factors affecting metformin concentrations after chronic administration in patients with polycystic ovary syndrome (PCOS), focusing on the pharmacokinetic variability and its implications for personalized therapy. METHODS: This study enrolled 53 PCOS patients undergoing long-term metformin treatment at the Clinic for Gynecology and Obstetrics in Nis, Serbia, from February to December 2019. Pharmacokinetic parameters were measured from blood samples, and metformin concentrations were determined with validated analytical techniques. RESULTS: There was a significant variability in metformin concentrations among PCOS patients, with body mass index (BMI) identified as a major influencing factor. Higher BMI was associated with lower plasma metformin levels, a finding suggesting an altered pharmacokinetic profile in obese patients. CONCLUSIONS: This study highlights the critical role of BMI in influencing metformin pharmacokinetics in PCOS patients and underscores the need for personalized treatment strategies in patients with PCOS.

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.

Absence of Metformin in Fetal Circulation Following Maternal Administration in Late Gestation Pregnant Sheep.

In human pregnancy, metformin administered to the mother crosses the placenta resulting in metformin exposure to the fetus. However, the effects of metformin exposure on the fetus are poorly understood and difficult to study in humans. Pregnant sheep are a powerful large animal model for studying fetal physiology. The objective of this study was to determine if maternally administered metformin at human dose-equivalent concentrations crosses the ovine placenta and equilibrates in the fetal circulation. To test this, metformin was administered to the pregnant ewe via continuous intravenous infusion or supplementation in the drinking water. Both administration routes increased maternal metformin concentrations to human dose-equivalent concentrations of ~ 10 µM, yet metformin was negligible in the fetus even after 3-4 days of maternal administration. In cotyledon and caruncle tissue, expression levels of the major metformin uptake transporter organic cation transporter 1 (OCT1) were < 1% of expression levels in the fetal liver, a tissue with abundant expression. Expression of other putative uptake transporters OCT2 and OCT3, and efflux transporters multidrug and toxin extrusion (MATE)1 and MATE2were more abundant. These results demonstrate that the ovine placenta is impermeable to maternal metformin administration. This is likely due to anatomical differences and increased interhaemal distance between the maternal and umbilical circulations in the ovine versus human placenta limiting placental metformin transport.

Understanding adefovir pharmacokinetics as a component of a transporter phenotyping cocktail.

PURPOSE: Adefovir (as dipivoxil) was selected as a probe drug in a previous transporter cocktail phenotyping study to assess renal organic anion transporter 1 (OAT1), with renal clearance (CLR) as the primary parameter describing renal elimination. An approximately 20% higher systemic exposure of adefovir was observed when combined with other cocktail components (metformin, sitagliptin, pitavastatin, and digoxin) compared to sole administration. The present evaluation applied a population pharmacokinetic (popPK) modeling approach to describe adefovir pharmacokinetics as a cocktail component in more detail. METHODS: Data from 24 healthy subjects were reanalyzed. After establishing a base model, covariate effects, including the impact of co-administered drugs, were assessed using forward inclusion then backward elimination. RESULTS: A one-compartment model with first-order absorption (including lag time) and a combination of nonlinear renal and linear nonrenal elimination best described the data. A significantly higher apparent bioavailability (73.6% vs. 59.0%) and a lower apparent absorption rate constant (2.29 h-1 vs. 5.18 h-1) were identified in the combined period compared to the sole administration period, while no difference was seen in renal elimination. The population estimate for the Michaelis-Menten constant (Km) of the nonlinear renal elimination was 170 nmol/L, exceeding the observed range of adefovir plasma maximum concentration, while the maximum rate (Vmax) of nonlinear renal elimination was 2.40 µmol/h at the median absolute estimated glomerular filtration rate of 105 mL/min. CONCLUSION: The popPK modeling approach indicated that the co-administration primarily affected the apparent absorption and/or prodrug conversion of adefovir dipivoxil, resulting in the minor drug-drug interaction observed for adefovir as a victim. However, renal elimination remained unaffected. The high Km value suggests that assessing renal OAT1 activity by CLR has no relevant misspecification error with the cocktail doses used.

A Drug-Drug Interaction Study to Evaluate the Impact of Rimegepant on OCT2- and MATE1-Mediated Transport of Metformin in Healthy Participants.

Rimegepant is a calcitonin gene-related peptide receptor antagonist approved for migraine treatment. This phase 1, open-label, single-center, fixed-sequence study evaluated the effect of rimegepant on the pharmacokinetics (PK) of metformin. Twenty-eight healthy participants received metformin 500 mg twice daily from Days 1 to 4 and Days 7 to 10, and once daily on Days 5 and 11. Rimegepant, 75 mg tablet, was administered once daily from Days 9 to 12. At pre-specified time points, plasma metformin concentration, serum glucose levels, and safety and tolerability were evaluated. A 16% increase in the area under the plasma metformin concentration-time curve (AUC) for 1 dosing interval (AUC0-τ,ss), a statistically insignificant increase in maximum and minimum steady-state metformin concentration (Cmax,ss and Cmin,ss), and a decrease in metformin renal clearance were observed on Day 11 following metformin-rimegepant coadministration compared with metformin alone; however, the changes were not clinically relevant. Additionally, coadministration of rimegepant with metformin did not induce clinically meaningful change in the maximum observed glucose concentration (Gmax) or AUCgluc compared with metformin alone. Overall, rimegepant and metformin coadministration did not result in clinically relevant changes in metformin PK, renal clearance, or the antihyperglycemic effects of metformin. Rimegepant is considered safe for use with metformin.

Effect of Cimetidine on Metformin Pharmacokinetics and Endogenous Metabolite Levels in Rats.

Tubular secretion is a primary mechanism along with glomerular filtration for renal elimination of drugs and toxicants into urine. Organic cation transporters (OCTs) and multidrug and toxic extrusion (MATE) transporters facilitate the active secretion of cationic substrates, including drugs such as metformin and endogenous cations. We hypothesized that administration of cimetidine, an Oct/Mate inhibitor, will result in increased plasma levels and decreased renal clearance of metformin and endogenous Oct/Mate substrates in rats. A paired rat pharmacokinetic study was carried out in which metformin (5 mg/kg, intravenous) was administered as an exogenous substrate of Oct/Mate transporters to six Sprague-Dawley rats with and without cimetidine (100 mg/kg, intraperitoneal). When co-administered with cimetidine, metformin area under the curve increased significantly by 3.2-fold, and its renal clearance reduced significantly by 73%. Untargeted metabolomics was performed to investigate the effect of cimetidine on endogenous metabolome in the blood and urine samples. Over 8,000 features (metabolites) were detected in the blood, which were shortlisted using optimized criteria, i.e., a significant increase (P value < 0.05) in metabolite peak intensity in the cimetidine-treated group, reproducible retention time, and quality of chromatogram peak. The metabolite hits were classified into three groups that can potentially distinguish inhibition of i) extra-renal uptake transport or catabolism, ii) renal Octs, and iii) renal efflux transporters or metabolite formation. The metabolomics approach identified novel putative endogenous substrates of cationic transporters that could be tested as potential biomarkers to predict Oct/Mate transporter mediated drug-drug interactions in the preclinical stages. SIGNIFICANCE STATEMENT: Endogenous substrates of renal transporters in animal models could be used as potential biomarkers to predict renal drug-drug interactions in early drug development. Here we demonstrated that cimetidine, an inhibitor of organic cation transporters (Oct/Mate), could alter the pharmacokinetics of metformin and endogenous cationic substrates in rats. Several putative endogenous metabolites of Oct/Mate transporters were identified using metabolomics approach, which could be tested as potential transporter biomarkers to predict renal drug-drug interaction of Oct/Mate substrates.

The Effect of BI 730357 (Retinoic Acid-Related Orphan Receptor Gamma t Antagonist, Bevurogant) on the Pharmacokinetics of a Transporter Probe Cocktail, Including Digoxin, Furosemide, Metformin, and Rosuvastatin: An Open-Label, Non-randomized, 2-Period Fixed-Sequence Trial in Healthy Subjects.

Evaluating Drug-Drug Interactions (DDIs) for new investigational compounds requires several trials evaluating different drugs with different transporter specificities. By using a cocktail of drugs with different transporter specificities, a single trial could evaluate the pharmacokinetics (PKs) of each cocktail drug simultaneously, reducing the number of clinical DDI trials required for clinical development. We aimed to investigate the effect of steady-state Boehringer Ingelheim (BI) 730357 (bevurogant) on the PKs of a validated and optimized 4-component transporter cocktail. This open-label, non-randomized, 2-period fixed-sequence phase I trial compared transporter cocktail (0.25 mg digoxin/1 mg furosemide/10 mg metformin hydrochloride/10 mg rosuvastatin) with and without BI 730357 in healthy subjects aged 18-55 years with body mass index 18.5-29.9 kg/m2 . During reference treatment/period 1, transporter cocktail was administered 90 minutes after breakfast. After a washout period, during test treatment/period 2, BI 730357 was dosed twice daily for 13 days, with transporter cocktail administered on day 1. The primary endpoints were the area under the concentration-time curve of the analyte in plasma over the time interval from 0 extrapolated to infinity (AUC0-∞ ) and the maximum measured concentration of the analyte in plasma (Cmax ), and the secondary endpoint was the area under the concentration-time curve of the analyte in plasma over the time interval from 0 to the last quantifiable data point (AUC0-tz ). Steady-state BI 730357 increased digoxin (+48% to +94%), minimally affected metformin (-2% to -9%), furosemide (+12% to +18%), and rosuvastatin (+19% to +39%) exposure. Therefore, no clinically relevant inhibition of transporters OCT2/MATE-1/MATE-2K, OAT1/OAT3, OATP1B1/OATP1B3 was observed. Potential inhibition of breast cancer resistance protein noted as PK parameters of coproporphyrin I/III (OATP1B1/OATP1B3 biomarkers) remained within bioequivalence boundaries while rosuvastatin PK parameters (AUC0-∞ /Cmax /AUC0-tz ) exceeded the bioequivalence boundary. BI 730357 was safe and well tolerated. This trial confirms the usefulness and tolerability of the transporter cocktail consisting of digoxin, furosemide, metformin, and rosuvastatin in assessing drug-transporter interactions in vivo.

Pharmacokinetic Interaction Between Imatinib and Metformin in Rats.

BACKGROUND AND OBJECTIVE: Imatinib is primarily transported into the liver by organic cation transporter 1 (OCT1), organic anion transporting polypeptide 1B3 (OATP1B3), and novel organic cation transporter 2 (OCTN2), which is the first step in the metabolic and elimination of imatinib. Patients taking imatinib may concurrently take metformin, a substrate for OCT1. Drug-drug interactions (DDI) may occur between imatinib and metformin, affecting the clinical efficacy of imatinib. This experiment aimed to investigate the pharmacokinetic effects of metformin on imatinib and its active metabolism of N-desmethyl imatinib in rats. METHODS: Twenty healthy Sprague-Dawley rats were selected and randomly divided into control and experimental groups (10 rats per group). The control group was orally administered imatinib (30 mg/kg) for 14 days, and the experimental group was orally co-administered imatinib (30 mg/kg) and metformin (200 mg/kg) for 14 days. The plasma concentrations of imatinib and N-desmethyl imatinib in rats were determined by ultra-performance liquid chromatography-mass spectrometry. Pharmacokinetic parameters were calculated by DAS2.0 software. RESULTS: After single-dose co-administration of imatinib and metformin on day 1, the AUC0-24 (area under the plasma concentration-time curve) and Cmax (maximum concentration) of imatinib and the MRT (mean residence time) and Cmax of N-desmethyl imatinib in the experimental group were significantly decreased compared with the control group (P < 0.05). After multiple-dose co-administration of imatinib and metformin for 14 days, the AUC0-24 and Cmax of both imatinib and N-desmethyl imatinib were significantly decreased in the experimental group (P < 0.05). CONCLUSION: With both single and multiple co-administration doses, metformin significantly changed the pharmacokinetic parameters of imatinib and N-desmethyl imatinib. The results suggest that care should be taken when metformin and imatinib are co-administered.

Identification of clinical and pharmacogenetic factors influencing metformin response in Type 2 diabetes mellitus.

Metformin, a hypoglycemic drug for Type 2 diabetes mellitus, shows variability in pharmacokinetics and response due to membrane transporters. This study followed 34 Type 2 diabetes mellitus patients on metformin treatment. Genetic variants in 11 metformin transport-related genes were analyzed, revealing associations. Specifically, SLC47A1 rs2289669 A/A and SLC22A4 rs1050152 T/T genotypes correlated with glycated hemoglobin values at 6 months. SLC47A1 rs2289669 G/A genotype influenced glucose levels at 6 months, while SLC29A4 rs3889348 A/A, SLC47A1 rs2289669 A/A, SLC22A4 rs1050152 C/T and SLC47A2 rs12943590 A/A genotypes were linked to glucose levels at 12 months. Additionally, ABCB1 rs2032582 C/A and ABCG2 rs2231137 C/T genotypes impacted cholesterol levels at 12 months. These findings shed light on metformin response determinants, offering insights for further research.

Goldenseal-Mediated Inhibition of Intestinal Uptake Transporters Decreases Metformin Systemic Exposure in Mice.

Goldenseal is a perennial plant native to eastern North America. A recent clinical study reported goldenseal decreased metformin Cmax and area under the blood concentration versus time curve (AUC) by 27% and 23%, respectively, but half-life and renal clearance were unchanged. These observations suggested goldenseal altered processes involved in metformin absorption. The underlying mechanism(s) remain(s) unknown. One mechanism for the decreased metformin systemic exposure is inhibition by goldenseal of intestinal uptake transporters involved in metformin absorption. Goldenseal extract and three goldenseal alkaloids (berberine, (-)-ß-hydrastine, hydrastinine) were tested as inhibitors of organic cation transporter (OCT) 3, plasma membrane monoamine transporter (PMAT), and thiamine transporter (THTR) 2 using human embryonic kidney 293 cells overexpressing each transporter. The goldenseal extract, normalized to berberine content, was the strongest inhibitor of each transporter (IC50: 4.9, 13.1, and 5.8 µM for OCT3, PMAT, and THTR2, respectively). A pharmacokinetic study in mice compared the effects of berberine, (-)-ß-hydrastine, goldenseal extract, and imatinib (OCT inhibitor) on orally administered metformin. Goldenseal extract and imatinib significantly decreased metformin Cmax by 31% and 25%, respectively, and had no effect on half-life. Berberine and (-)-ß-hydrastine had no effect on metformin pharmacokinetics, indicating neither alkaloid alone precipitated the interaction in vivo. A follow-up murine study involving intravenous metformin and oral inhibitors examined the contributions of basolateral enteric/hepatic uptake transporters to the goldenseal-metformin interaction. Goldenseal extract and imatinib had no effect on metformin AUC and half-life, suggesting lack of inhibition of basolateral enteric/hepatic uptake transporters. Results may have implications for patients taking goldenseal with drugs that are substrates for OCT3 and THTR2. SIGNIFICANCE STATEMENT: Goldenseal is used to self-treat respiratory infections and digestive disorders. We investigated potential mechanisms for the clinical pharmacokinetic interaction observed between goldenseal and metformin, specifically inhibition by goldenseal of intestinal uptake transporters (OCT3, PMAT, THTR2) involved in metformin absorption. Goldenseal extract inhibited all three transporters in vitro and decreased metformin systemic exposure in mice. These data may have broader implications for patients co-consuming goldenseal with other drugs that are substrates for these transporters.

Pharmacokinetic Variables of Dapagliflozin/Metformin Extended-release Fixed-dose Combination in Healthy Chinese Volunteers and Regional Comparison.

PURPOSE: A fixed-dose combination (FDC) product combining dapagliflozin and metformin may increase medication adherence in patients with type 2 diabetes mellitus (T2DM) by minimizing pill burden associated with co-administration of individual component (IC) formulations and, consequently, improve cost-efficiency and compliance. This study evaluated the bioequivalence of the dapagliflozin/metformin FDC product versus IC administration in healthy volunteers from a Chinese population and assessed the safety profile of the FDC product. In addition, pharmacokinetic (PK) and safety comparisons of dapagliflozin and metformin across different regions were conducted to evaluate regional differences. METHODS: This single-center, open-label, parallel-cohort, randomized, 2-period, crossover study enrolled Chinese adults (aged 18-55 years). Volunteers in cohort 1 received either a single FDC tablet of dapagliflozin/metformin extended release (XR) (5/500 mg) or IC tablets (dapagliflozin [5 mg] and metformin XR [500 mg]). Volunteers in cohort 2 received a higher dosage in a similar manner (dapagliflozin [10 mg] and metformin XR [1000 mg]). Volunteers in each cohort were subsequently crossed over to receive the alternate cohort treatment. Plasma concentrations of dapagliflozin and metformin were determined, and bioequivalence analyses were performed under standard fed conditions. FINDINGS: Eighty healthy Chinese volunteers (89.9% male; mean age, 28.7 years) were randomized into cohort 1 (n = 40) and cohort 2 (n = 39; 1 volunteer withdrew before receiving study treatment). The mean plasma concentration-time profiles of the dapagliflozin and metformin FDC and IC formulations for both doses were found to be nearly superimposable. Dapagliflozin and metformin XR FDC were bioequivalent to the IC tablets, with 90% CIs for each pairwise comparison contained within the 80% to 125% bioequivalence limits. Both the FDC and IC formulations were well tolerated, with no serious adverse events/death. PK parameters for dapagliflozin in the Chinese volunteers were slightly to moderately higher than those from studies conducted in Brazil, Russia, and the United States, and the safety profile of the dapagliflozin/metformin FDC product was consistent with that of other studies. The difference in PK parameters among the 4 regions was not clinically meaningful. IMPLICATIONS: The bioequivalence of the dapagliflozin/metformin FDC and IC formulations in healthy Chinese adults was established without any new safety concerns. Notably, the observed bioequivalence may be extrapolated to patients with T2DM as the PK parameters of dapagliflozin and metformin in healthy adults are similar to those reported in patients with T2DM. CLINICALTRIALS: gov identifier: NCT04856007.

Pharmacokinetic Comparison Between a Fixed-Dose Combination of Empagliflozin L-Proline/Metformin and Empagliflozin/Metformin in Healthy Korean Subjects.

Empagliflozin and metformin are oral antidiabetic drugs commonly used to treat type 2 diabetes mellitus as a combination therapy. This study aimed to compare the pharmacokinetics and safety of a newly developed fixed-dose combination of 5-mg empagliflozin L-proline and 1000-mg metformin with the reference drug. A randomized, open-label, single-dose, 2-period, 2-treatment, crossover study was conducted in healthy Korean subjects. The subjects received a single oral dose of reference drug or test drug at each period. The pharmacokinetic (PK) parameters were calculated using a noncompartmental method. The geometric mean ratios and 90% confidence intervals of the plasma maximum concentration (Cmax ) and area under the concentration-time curve from time zero to the last quantifiable concentration (AUClast ) were calculated. A total of 27 healthy subjects were included in the PK analysis. For empagliflozin, the geometric mean ratios (90% confidence intervals) of the test to reference drug for Cmax and AUClast were 1.03 (0.99-1.08) and 1.03 (1.00-1.06), respectively. For metformin, the corresponding values for Cmax  and AUClast were 0.99 (0.92-1.06) and 1.00 (0.94-1.06), respectively. In conclusion, a fixed-dose combination of empagliflozin L-proline and metformin showed similar PK characteristics to the reference drug, and both drugs were safe in healthy subjects.

The development and benefits of metformin in various diseases.

Metformin has been used for the treatment of type II diabetes mellitus for decades due to its safety, low cost, and outstanding hypoglycemic effect clinically. The mechanisms underlying these benefits are complex and still not fully understood. Inhibition of mitochondrial respiratory-chain complex I is the most described downstream mechanism of metformin, leading to reduced ATP production and activation of AMP-activated protein kinase (AMPK). Meanwhile, many novel targets of metformin have been gradually discovered. In recent years, multiple pre-clinical and clinical studies are committed to extend the indications of metformin in addition to diabetes. Herein, we summarized the benefits of metformin in four types of diseases, including metabolic associated diseases, cancer, aging and age-related diseases, neurological disorders. We comprehensively discussed the pharmacokinetic properties and the mechanisms of action, treatment strategies, the clinical application, the potential risk of metformin in various diseases. This review provides a brief summary of the benefits and concerns of metformin, aiming to interest scientists to consider and explore the common and specific mechanisms and guiding for the further research. Although there have been countless studies of metformin, longitudinal research in each field is still much warranted.

Novel Explanted Human Liver Model to Assess Hepatic Extraction, Biliary Excretion and Transporter Function.

Realistic models predicting hepatobiliary processes in health and disease are lacking. We therefore aimed to develop a physiologically relevant human liver model consisting of normothermic machine perfusion (NMP) of explanted diseased human livers that can assess hepatic extraction, clearance, biliary excretion, and drug-drug interaction (DDI). Eleven livers were included in the study, seven with a cirrhotic and four with a noncirrhotic disease background. After explantation of the diseased liver, NMP was initiated. After 120 minutes of perfusion, a drug cocktail (rosuvastatin, digoxin, metformin, and furosemide; OATP1B1/1B3, P-gp, BCRP, and OCT1 model compounds) was administered to the portal vein and 120 minutes later, a second bolus of the drug cocktail was co-administered with perpetrator drugs to study relevant DDIs. The explanted livers showed good viability and functionality during 360 minutes of NMP. Hepatic extraction ratios close to in vivo reported values were measured. Hepatic clearance of rosuvastatin and digoxin showed to be the most affected by cirrhosis with an increase in maximum plasma concentration (Cmax ) of 11.50 and 2.89 times, respectively, compared with noncirrhotic livers. No major differences were observed for metformin and furosemide. Interaction of rosuvastatin or digoxin with perpetrator drugs were more pronounced in noncirrhotic livers compared with cirrhotic livers. Our results demonstrated that NMP of human diseased explanted livers is an excellent model to assess hepatic extraction, clearance, biliary excretion, and DDI. Gaining insight into pharmacokinetic profiles of OATP1B1/1B3, P-gp, BCRP, and OCT1 model compounds is a first step toward studying transporter functions in diseased livers.

Genetic variation in organic cation transporters and considerations in drug development.

INTRODUCTION: Membrane transporters are now widely recognized for their role in the absorption, distribution, clearance, and elimination of drugs. The organic cation transporters (OCTs, SLC22A) are expressed in the intestine, liver, and kidneys and are of importance in determining systemic pharmacokinetics (PK) and tissue-specific exposure of drugs and metabolites. AREAS COVERED: An overview of the role of OCTs in drug disposition is presented. Genetic variation in OCTs and the effects on PK and drug response were discussed. EXPERT OPINION: Clinical studies demonstrated significance of OCT1 and OCT2 in the hepatic uptake and renal secretion of drug, respectively. These mechanisms are important in determining the systemic PK and tissue exposure and thus pharmacodynamics of several drugs (e.g. metformin, morphine, sumatriptan). Emerging pharmacogenomic data also suggests multidrug and toxin extrusion pump (MATE1, SLC47A1) contribution to PK and response of drugs like metformin and cisplatin. Considerations to genotyping of functional and common variants of OCTs should be given, particularly for cationic drugs with hepatic elimination or renal secretion being major clearance pathways, in the clinical development. While the current evidence indicate that pharmacokinetic variability associated with known genotypes of OCTs/MATEs is relatively small, they may be of relevance in the tissue-specific effects and for drugs with low therapeutic index.

Evaluation of Drug-Drug Interactions of Ensitrelvir, a SARS-CoV-2 3CL Protease Inhibitor, With Transporter Substrates Based on In Vitro and Clinical Studies.

Drug-drug interaction potentials of ensitrelvir, a novel oral inhibitor of 3C-like protease of severe acute respiratory syndrome coronavirus 2, for drug transporters were evaluated by in vitro and clinical studies. The target drug transporters assessed were P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), organic anion transporting polypeptide (OATP) 1B1, OATP1B3, organic anion transporter (OAT) 1, OAT3, organic cation transporter (OCT) 1, OCT2, and multidrug and toxin extrusion 1 and 2K. In vitro study revealed that ensitrelvir is a substrate for P-gp and BCRP and inhibits P-gp, BCRP, OATP1B1, OATP1B3, OCT1, and OAT3. Based on these results, a clinical drug-drug interaction study to evaluate the effect of ensitrelvir on the pharmacokinetics of P-gp, BCRP, OATP1B1, OATP1B3, and OCT1 substrates was conducted with a cocktail approach using digoxin (P-gp substrate), rosuvastatin (BCRP, OATP1B1, and OATP1B3 substrate), and metformin (OCT1 substrate). The cocktail was administered first, and after the washout period, the cocktail was coadministered with 500 mg of ensitrelvir. No treatment-emergent adverse events were observed. Pharmacokinetic analyses demonstrated that the ratios (90% confidence intervals) of "cocktail with ensitrelvir" to "cocktail without ensitrelvir" for maximum plasma concentration and area under the plasma concentration-time curve were, respectively, 2.17 (1.72-2.73) and 1.31 (1.13-1.52) for digoxin, 1.97 (1.73-2.25) and 1.65 (1.47-1.84) for rosuvastatin, and 1.03 (0.91-1.16) and 1.02 (0.94-1.11) for metformin. The results indicate that the exposure levels of digoxin and rosuvastatin increased when coadministered with ensitrelvir, but those of metformin were not changed. In conclusion, ensitrelvir has an impact on the exposure levels of P-gp, BCRP, OATP1B1, and OATP1B3 substrates.

Significant impact of time-of-day variation on metformin pharmacokinetics.

AIMS/HYPOTHESIS: The objective was to investigate if metformin pharmacokinetics is modulated by time-of-day in humans using empirical and mechanistic pharmacokinetic modelling techniques on a large clinical dataset. This study also aimed to generate and test hypotheses on the underlying mechanisms, including evidence for chronotype-dependent interindividual differences in metformin plasma and efficacy-related tissue concentrations. METHODS: A large clinical dataset consisting of individual metformin plasma and urine measurements was analysed using a newly developed empirical pharmacokinetic model. Causes of daily variation of metformin pharmacokinetics and interindividual variability were further investigated by a literature-informed mechanistic modelling analysis. RESULTS: A significant effect of time-of-day on metformin pharmacokinetics was found. Daily rhythms of gastrointestinal, hepatic and renal processes are described in the literature, possibly affecting drug pharmacokinetics. Observed metformin plasma levels were best described by a combination of a rhythm in GFR, renal plasma flow (RPF) and organic cation transporter (OCT) 2 activity. Furthermore, the large interindividual differences in measured metformin concentrations were best explained by individual chronotypes affecting metformin clearance, with impact on plasma and tissue concentrations that may have implications for metformin efficacy. CONCLUSIONS/INTERPRETATION: Metformin's pharmacology significantly depends on time-of-day in humans, determined with the help of empirical and mechanistic pharmacokinetic modelling, and rhythmic GFR, RPF and OCT2 were found to govern intraday variation. Interindividual variation was found to be partly dependent on individual chronotype, suggesting diurnal preference as an interesting, but so-far underappreciated, topic with regard to future personalised chronomodulated therapy in people with type 2 diabetes.

Pharmacokinetic and Bioequivalence Studies of 2 Metformin Glibenclamide Tablets in Healthy Chinese Subjects Under Fasting and Fed Conditions.

The rational combination of oral antidiabetic agents is more likely to provide better glycemic control than monotherapy. Metformin glibenclamide tablets can be used as second-line therapy for patients with type 2 diabetes mellitus who cannot successfully control their blood glucose levels by diet and exercise plus metformin or sulfonylureas. The aim of this study was to evaluate the bioequivalence and safety of metformin hydrochloride and glibenclamide tablets (500 mg/5 mg) prepared by 2 different vendors in healthy Chinese subjects under fasting and fed conditions. This is an open-label, single-center, randomized, 2-formulation, 2-period crossover study. After screening, 40 subjects were enrolled in the fasting trial, while 40 subjects were enrolled in the fed trial. Qualified subjects were randomly assigned to receive a monotherapy dose of 500 mg/5 mg of the test or reference formulation, and after a 1-week washout period, they took the alternative formulation. Blood samples were collected from 24 blood collection sites per cycle for pharmacokinetic analysis until 36 hours after oral administration. In total, 78 subjects completed the study. Under fasting and fed conditions, the geometric mean ratios of maximum plasma concentration, area under the plasma concentration-time curve (AUC) from time 0 to time of last quantifiable drug level , and AUC from time 0 to infinity between the 2 products, as well as the corresponding 90%CIs, were all within the range of 80%-125%. It was found that exposure (AUC from time 0 to infinity) to metformin is decreased by about 25% in the fed state compared to fasting, whereas glibenclamide exposure is increased by about 30% in the fed state. No severe adverse events were observed in the study.

Effects of Food and Multiple-dose Administration on the Pharmacokinetic Properties of HR20033, a Sustained-release Formulation of Henagliflozin and Metformin for the Treatment of Diabetes, in Healthy Chinese Volunteers.

Henagliflozin proline and metformin hydrochloride sustained-release tablets (HR20033) are a fixed-dose combination of the novel, highly selective, and effective sodium-glucose cotransporter-2 inhibitor henagliflozin, with a metformin sustained-release layer for the treatment of type 2 diabetes mellitus in conjunction with dietary control and exercise. The aims of this study were to investigate the effect of a high-fat diet on the pharmacokinetics of henagliflozin and metformin after a single administration of HR20033 and the effect of repeated oral administration of HR20033 on their pharmacokinetics in healthy volunteers. The food-effect clinical study involved 18 healthy subjects randomized to receive either HR20033 in the fasted condition followed by HR20033 in the fed condition or the reverse schedule, with the two doses separated by a washout period of at least 7 days. The multiple-dose clinical study was conducted on 10 healthy subjects. In the food-effect study, compared with those in the fasted condition, the area under the blood concentration curve (AUC) and peak concentration (Cmax ) of henagliflozin decreased by 12.64% and 40.89%, respectively, while the AUC of metformin increased by 31.13% and Cmax decreased by 7.09% in the fed state. There was no significant accumulation of HR20033 in the body after multiple oral doses. No serious adverse event was observed in either of the two clinical studies. Food did not have a clinically meaningful effect on the absorption of HR20033.