Pharmacokinetics Of Metformin Research Articles

Rs622342A>C in SLC22A1 is associated with metformin pharmacokinetics and glycemic response

Polymorphisms in SLC22A1 lead to variability in metformin clinical efficacy. Sixty-three Lebanese patients with type 2 diabetes who administered metformin, were followed up for six months and genotyped for rs622342A>C. The area under the plasma concentration-time curve and the maximum concentration of metformin was highest in CC patients (P ≤ 0.03). There was a significant difference between groups in the percentage decrease in fasting blood sugar (FBS) and glycated hemoglobin (HbA1c). Going into the same direction, rs622342C was associated with decrease in FBS levels after three and six months of treatment (P ≤ 0.02), whereas with HbA1c, the decrease was noticed after six months (β = −2.78; P = 0.03). In contrast, the serum levels of lactate and creatinine did not vary significantly according to rs622342A>C genotypes.The rs622342A>C in SLC22A1 may be associated with metformin pharmacokinetics and variability in therapeutic efficacy.

Pharmacokinetic Interaction of Green Rooibos Extract With Atorvastatin and Metformin in Rats.

An aspalathin-rich green rooibos extract (Afriplex GRT™) has demonstrated anti-diabetic and hypolipidemic properties, while also moderately inhibiting CYP3A4 activity, suggesting a potential for herb–drug interaction. The present study, therefore, evaluated the effects of orally administered GRT on the pharmacokinetics of atorvastatin and metformin in Wistar rats. Wistar rats were orally treated with GRT (50 mg/kg BW), atorvastatin (40 mg/kg BW) or metformin (150 mg/kg BW) alone or 50 mg/kg BW GRT in combination with 40 mg/kg BW atorvastatin or 150 mg/kg BW metformin. Blood samples were collected at 0, 10, and 30 min and 1, 2, 4, 6, and 8 h and plasma samples obtained for Liquid chromatography-mass spectrometry (LC-MS/MS) analyses. Non-compartment and two-compartment pharmacokinetic parameters of atorvastatin and metformin in the presence or absence of GRT were determined by PKSolver version 2.0 software. Membrane transporter proteins, ATP-binding cassette sub-family C member 2 (Abcc2), solute carrier organic anion transporter family, member 1b2 (Slco1b2), ATP-binding cassette, sub-family B (MDR/TAP), member 1A (Abcb1a), and organic cation transporter 1 (Oct1) mRNA expression were determined using real-time PCR expression data normalized to β-actin and hypoxanthine-guanine phosphoribosyltransferase (HPRT), respectively. Co-administration of GRT with atorvastatin substantially increased the maximum plasma concentration (Cmax) and area of the plasma concentration–time curve (AUC0-8) of atorvastatin by 5.8-fold (p = 0.03) and 5.9-fold (p = 0.02), respectively. GRT had no effect on the plasma levels of metformin. GRT increased Abcc2 expression and metformin downregulated Abcb1a expression while the combination of GRT with atorvastatin or metformin did not significantly alter the expression of Slco1b1 or Oct1 did not significantly alter the expression of Sclo1b2 or Oct1. Co-administration of GRT with atorvastatin in rats may lead to higher plasma concentrations and, therefore, to an increase of the exposure to atorvastatin.

A randomized controlled trial on the efficacy, safety, and pharmacokinetics of metformin in severe traumatic brain injury.

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality worldwide. Metformin is reported to have pleiotropic neuroprotective effects through anti-inflammatory, antioxidative, and anti-ischemic activity, and improvements in vascular hemodynamics and endothelial function. The aim of this study is to examine the efficacy and safety of metformin therapy in severe TBI patients. This single-blind, parallel-group, randomized controlled trial enrolled adult TBI patients. Of 158 trauma patients assessed, 30 met the eligibility criteria and were randomly allocated in a one-to-one ratio to receive 1g metformin every 12h for five consecutive days (intervention group) or to usual management only (control group). For efficacy analysis, temporal profiles of serum levels of S100b, neutrophil to lymphocyte ratio (NLR), and glial fibrillary acidic protein (GFAP) were assessed. For pharmacokinetic analysis, serum concentrations of metformin were evaluated in the intervention group. The two study groups were similar in terms of demographics, baseline clinical characteristics, and on-admission biomarkers' serum levels. Longitudinal analysis of S100b and NLR levels showed statistically significant declines in values toward normal levels in the intervention group (p values of < 0.001 and 0.030, respectively), different from the profiles of the control group (p values of 0.074 and 0.645, respectively). Pharmacokinetic analysis demonstrated that metformin absorption is delayed in TBI patients. No events of hypoglycemia and lactic acidosis occurred. Metformin could potentially be an effective and safe therapeutic intervention in patients with severe TBI. Large-scale, multicentre studies are needed to confirm our encouraging results.

Lonicera japonica extract increases metformin distribution in the liver without change of systemic exposed metformin in rats

Ethnopharmacological relevanceFlower and flower bud of Lonicera japonica, Lonicerae Flos, have been popularly used as medicinal plant for the treatment of clearing heat and thirst, thereby improving diabetic or diabetic associated symptoms (thirst and poor eyesight). Aim of the studyOrganic cation transporters (OCTs) and multi-drug and toxin extrusion proteins (MATEs) are known to play important roles in metformin transport in the liver and kidneys. Thus, there might be interactions between Lonicerae Flos and metformin via OCTs and MATEs. Also treatment period has been issued in transporter-mediated drug interactions. The objective of this study was to determine the effect of Lonicerae Flos ethanol extract (LJ) on metformin pharmacokinetics and its glucose lowering activity in different treatment periods. Materials and methodsEffect of LJ on metformin uptake was evaluated in vitro HEK-293 cells expressing human OCTs or MATEs. Treatment period-dependent impact of LJ on systemic exposure and hepatic distribution of metformin as well as its glucose tolerance activity were assessed in in vivo rats. ResultsLJ substantially inhibited MATE1-mediated metformin uptake in vitro. In evaluating treatment period effects of LJ and metformin, 1-, 7-, and 28-day co-treatments of LJ with metformin did not change systemic exposure of metformin compared to those in metformin alone. Whereas, 28-day co-treatment of LJ with metformin increased metformin concentration in liver as a pharmacological target site of metformin. It could be due to the reduced MATE1-mediated metformin efflux from hepatocytes to bile by MATE1 inhibition in liver. Glucose tolerance activity was also enhanced by 28-day co-treatment of LJ and metformin compared to metformin alone. ConclusionsIn 28-day co-treatment of LJ and metformin, LJ increased metformin concentration in liver and improved glucose tolerance activity without systemic exposure change of metformin, suggesting the importance to consider treatment period effect and both systemic exposure and tissue distribution in drug interactions.

In vivo pharmacodynamic and pharmacokinetic effects of metformin mediated by the gut microbiota in rats

AimsThe gut microbiota plays a crucial role in the efficacy of metformin in T2DM treatment. We evaluated whether the pharmacodynamics and pharmacokinetics of metformin are mediated by gut microbiota. Main methodsWe used conventional diabetic and pseudo-germ-free rats. After 6 weeks of metformin treatment, pharmacodynamic indexes were determined. Metformin concentrations were measured with a validated HPLC-MS/MS method after the first oral administration. Key findingsMost endpoints were similar between vehicle-treated diabetic and vehicle-treated pseudo-germ-free diabetic rats. However, after 6 weeks of metformin treatment, compared with conventional diabetic rats, pseudo-germ-free diabetic rats exhibited significantly increased FBG, decreased oral glucose, reduced GSP, worsened insulin resistance, increased hyperlipidemia, and increased hepatic steatosis severity. Moreover, the Cmax of pseudo-germ-free rats increased significantly, while the t1/2α decreased significantly. These pharmacodynamic and pharmacokinetic changes were probably due to a decrease in Oct1 expression in the liver, resulting in altered hepatic uptake of metformin in vivo. SignificanceThese results implied that the gut microbiota may play an important role in the pharmacodynamics and pharmacokinetics of metformin and that the changes in these properties are probably due to Oct1 downregulation in the livers of pseudo-germ-free rats.

Pharmacokinetics simulation of Metformin in type 2 Diabetes Mellitus

The aim of this study was to explore the pharmacokinetic relationship of metformin on glucose levels after the administration of metformin in type 2 diabetes mellitus. The pharmacokinetics of metformin was assessed using intravenous glucose tolerance tests before and after metformin administration. Type 2 diabetes mellitus is a metabolic disturbance which is caused by the pancreas that cannot produce enough insulin or body cannot use insulin which is produced effectively (low insulin sensitivity). Therefore, there is glucose level concentration escalation inside blood, where blood glucose level is more than normal level or known as hyperglycemia. Type 2 diabetes mellitus signed by muscle resistance and tissue to insulin, the decrement of insulin produced in the pancreas, and glucose absorption in the liver. Giving metformin to type 2 diabetes mellitus subjects increased glucose absorption in periphery tissue and liver but it did not impact insulin because metformin worked similarly to insulin and it did not impact beta cell function, so after or before metformin given, insulin concentration would not change, the effect of decrement of glucose following the concept of decay.

Evaluation of the pharmacokinetics of metformin and acarbose in the common marmoset.

ABSTRACTMetformin has beneficial effects on several age-related diseases (e.g., diabetes, obesity, cancer) and extends lifespan in nematodes and mice. Acarbose, an FDA-approved agent for treating type 2 diabetes, prevents breakdown of complex carbohydrates. Both compounds have been suggested as potential anti-aging interventions and acarbose has been shown to extend mouse longevity by the Intervention Testing Program (ITP). One potential next step is to assess the effect of these interventions on healthspan and lifespan in non-human primates. The common marmoset (Callithrix jacchus) is a small new world monkey with a relatively short life span and small size, both valuable for the translation potential of this nonhuman primate species for the study of aging and chronic disease. However, the dosing and assessment of potential side effects of either metformin or acarbose in this species have yet to be assessed. This study evaluated the pharmacokinetics of two dosage levels each of metformin or acarbose (given separately) in two small groups of young marmosets (n = 5/group) treated for 24 h to define the pharmacokinetics of each drug. The ability to rapidly and reliably dose socially housed marmosets with an oral form of acarbose or metformin that is well tolerated indicates that this species is a reliable model for testing acarbose and metformin in a safe and efficient way in a long-term intervention.

Simultaneous quantitation of metformin and dapagliflozin in human plasma by LC-MS/MS: Application to a pharmacokinetic study.

A single LC-MS/MS assay has been developed and validated for the simultaneous determination of metformin and dapagliflozin in human plasma using ion-pair solid-phase extraction. Chromatographic separation of the analytes and their internal standards was carried out on a reversed-phase ACE 5CN (150 × 4.6 mm, 5 μm) column using acetonitrile-15 mm ammonium acetate, pH 4.5 (70:30, v/v) as the mobile phase. To achieve higher sensitivity and selectivity for the analytes, mass spectrometric analysis was performed using a polarity switching approach. Ion transitions studied using multiple reaction monitoring mode were m/z 130.1 [M + H]+ /60.1 for metformin and m/z 467.1 [M + CH3 COO]- /329.1 for dapagliflozin in the positive and negative modes, respectively. The linear calibration range of the assay was established from 1.00 to 2000 ng/mL for metformin and from 0.10 to 200 ng/mL for dapagliflozin to achieve a better assessment of the pharmacokinetics of the drugs. The limit of detection and limit of quantitation for the analytes were 0.39 and 1.0 ng/mL for metformin and 0.03 and 0.1 ng/mL for dapagliflozin, respectively. There was no interference of plasma matrix obtained from different sources, including hemolyzed and lipemic plasma. The method was successfully applied to study the effect of food on the pharmacokinetics of metformin and dapagliflozin in healthy subjects.

Impact of Promoter Polymorphisms on the Transcriptional Regulation of the Organic Cation Transporter OCT1 (SLC22A1).

The organic cation transporter 1 (OCT1, SLC22A1) is strongly expressed in the human liver and facilitates the hepatic uptake of drugs such as morphine, metformin, tropisetron, sumatriptan and fenoterol and of endogenous substances such as thiamine. OCT1 expression is inter-individually highly variable. Here, we analyzed SNPs in the OCT1 promoter concerning their potential contribution to the variability in OCT1 expression. Using electrophoretic mobility shift and luciferase reporter gene assays in HepG2, Hep3B, and Huh7 cell lines, we identified the SNPs −1795G>A (rs6935207) and −201C>G (rs58812592) as having effects on transcription factor binding and/or promoter activity. The A-allele of the −1795G>A SNP showed allele-specific binding of the transcription factor NF-Y leading to 2.5-fold increased enhancer activity of the artificial SV40 promoter. However, the −1795G>A SNP showed no significant effects on the native OCT1 promoter activity. Furthermore, the −1795G>A SNP was not associated with the pharmacokinetics of metformin, fenoterol, sumatriptan and proguanil in healthy individuals or tropisetron efficacy in patients undergoing chemotherapy. Allele-dependent differences in USF1/2 binding and nearly total loss in OCT1 promoter activity were detected for the G-allele of −201C>G, but the SNP is apparently very rare. In conclusion, common OCT1 promoter SNPs have only minor effects on OCT1 expression.

The influence of telmisartan on metformin pharmacokinetics and pharmacodynamics

Metformin is the most widely used drug among type 2 diabetes mellitus patients. However, drug interaction on metformin will influence its glucose-lowering effect or increase its side effect of lactic acidosis. In this study, a randomized, two-stage, crossover study was conducted to unveil the potential drug interaction between metformin and the anti-hypertension drug, telmisartan. Totally, 16 healthy Chinese male volunteers were enrolled. Blood samples from various time-points after drug adminstration were analyzed for metformin quantification. Oral glucose tolerance test (OGTT) was conducted 2 h after metformin administration. The AUC0-12 and Cmax of metformin in subjects co-administrated with telmisartan were significantly lower than with placebo. The geometric mean ratios (value of metformin plus telmisartan phase/value of metformin plus placebo phase) for Cmax and AUC0-12 is 0.7972 (90%CI: 0.7202–0.8824) and 0.8336 (90%CI: 0.7696–0.9028), respectively. Moreover, telmisartan co-administration significantly increased the plasma concentrations of both glucose and insulin at 0.5 h since OGTT (7.64 ± 1.86 mmol/l·min vs 6.77 ± 0.83 mmol/l·min, P = 0.040; 72.91 ± 31.98 μIU/ml·min vs 60.20 ± 24.20 μIU/ml·min, P = 0.037), though the AUC of glucose and insulin after OGTT showed no significant difference. These findings suggested that telmisartan had a significant influence on the Pharmacokinetics of metformin in healthy groups, though the influence on glucose-lowering effect was moderate.

OCT3 promoter haplotype is associated with metformin pharmacokinetics in Koreans

Organic cation transporter 3 (OCT3) is expressed in various organs in humans and plays an important role in the transport of organic cations and drugs including metformin. In this study, we identified genetic variations of the OCT3 promoter and functionally characterized each variant by in vitro assays. Next, the association between the functional haplotype of the OCT3 promoter and pharmacokinetics of metformin was evaluated. In our study population, 7 variations and 2 major haplotypes were identified, of which H2 haplotype yielded a significantly higher luciferase activity than did the wild type. Two variants of H2, c.-1603G > A and c.-1547T > G, yielded significantly lower luciferase activities, whereas the luciferase activity of another variant, c.-29G > A, was significantly higher. Two transcription factors, Sp1 and USF1, were involved in the regulation of OCT3 transcription. Analysis of clinical data revealed that 25 subjects, either homozygous or heterozygous for H2, showed increased AUCinf and Cmax by 17.2% and 15.9%, respectively [P = 0.016 and 0.031, GMR (90% CI) = 1.17 (1.06–1.29) and 1.17 (1.04–1.31), respectively], compared to the 20 subjects in the control group. Our study suggests that an OCT3 promoter haplotype affects the pharmacokinetics of metformin in Koreans as well as the OCT3 transcription rate.

Effect of Food on the Pharmacokinetics of Ertugliflozin and Its Fixed‐Dose Combinations Ertugliflozin/Sitagliptin and Ertugliflozin/Metformin

Ertugliflozin, an inhibitor of sodium‐glucose cotransporter 2, is approved in the United States and European Union for the treatment of type 2 diabetes in adults, both as monotherapy and as part of fixed‐dose combination (FDC) therapies with either sitagliptin or immediate‐release metformin. The effect of a standard, high‐fat breakfast on the pharmacokinetics of the highest strengths of ertugliflozin monotherapy (15 mg), ertugliflozin/sitagliptin FDC (15‐/100‐mg), and ertugliflozin/metformin FDC (7.5‐/1000‐mg) tablets was evaluated. In 3 separate open‐label, 2‐period, 2‐sequence, single‐dose, crossover studies, 14 healthy subjects per study were randomized to receive either ertugliflozin monotherapy or FDC tablets comprising ertugliflozin and sitagliptin or ertugliflozin and metformin under fasted and fed (or vice versa) conditions. Food did not meaningfully affect the pharmacokinetics of ertugliflozin, sitagliptin, or metformin. For FDCs, the effect of food was consistent with that described for individual components. All treatments were well tolerated. Ertugliflozin and ertugliflozin/sitagliptin FDC tablets can be administered without regard to meals. As metformin is administered with meals because of its gastrointestinal side effects, the ertugliflozin/metformin FDC should also be administered with meals.

Pharmacokinetics of Metformin in Combination With Sitagliptin in Adult Horses After Enteral Administration

Insulin dysregulation (ID) is a common metabolic disorder in horses. Recently, incretin hormone release has been suggested to be involved in ID in horses. In human medicine, metformin and sitagliptin are commonly used in combination for metabolic syndrome. This combination could be useful in treating ID in horses. However, no pharmacokinetics data have been reported in this species. The objective of the present study was to establish the plasma concentration–time profile and to derive pharmacokinetics data for a combination of metformin and sitagliptin in horses after enteral administration. Six healthy adult Purebred Spanish horses were used. A metformin (15 mg/kg) plus sitagliptin (1.5 mg/kg) preparation was administered by intragastric route (IG) as an enteral solution. Blood samples were collected from 0 to 48 hours after IG drug administration. Plasma concentrations of metformin and sitagliptin were measured using high performance liquid chromatography methods. The t½λz for metformin was 2.9 hours and for sitagliptin 21 hours. The Cmax was 442 ± 84 mg/L within 0.9 hours for metformin and 94 ± 14 mg/L within 1.3 hours for sitagliptin. No adverse effects were observed, and the combination of metformin and sitagliptin was well tolerated. Therefore, these results suggest that metformin plus sitagliptin might be a combination to consider in horses with ID. Additional studies are needed to establish the effectiveness and tolerance in equids affected by endocrine disorders.

Using a semi-mechanistic model to identify the main sources of variability of metformin pharmacokinetics.

Metformin pharmacokinetics (PK) is highly variable, and researchers have for years tried to shed light on determinants of inter-individual (IIV) and inter-occasion variability (IOV) of metformin PK. We set out to identify the main sources of PK variability using a semi-mechanistic model. We assessed the influence of subject characteristics, including seven genetic variants. Data from three studies of healthy individuals with PK measurements of plasma and urine after single dose or at steady-state were used in this study. In total, 87 subjects were included (16 crossover subjects). Single nucleotide polymorphisms in ATM, OCT1, OCT2, MATE1 and MATE2-K were investigated as dominant, recessive or additive. A three-compartment model with transit absorption and renal elimination with a proportional error was fitted to the data using NONMEM 7.3. Oral parameters were separated from disposition parameters as dose-dependent absolute bioavailability was determined with support from urine data. Clearance was expressed as net renal secretion and filtration, assuming full fraction unbound and fraction excreted. Mean transit time and peripheral volume of distribution were identified as the main sources of variability according to estimates, with 94% IOV and 95% IIV, respectively. Clearance contributed only with 16% IIV. Glomerular filtration rate and body-weight were the only covariates found to affect metformin net secretion, reducing IIV to 14%. None of the genetic variants were found to affect metformin PK. Based on our analysis, finding covariates explaining absorption of metformin is much more valuable in understanding variability and avoiding toxicity than elimination.

Rifampicin Alters Metformin Plasma Exposure but Not Blood Glucose Levels in Diabetic Tuberculosis Patients.

The pharmacokinetic (PK) and clinical implications of combining metformin with rifampicin are relevant to increasing numbers of patients with diabetic tuberculosis (TB) across the world and are yet unclear. We assessed the impact of rifampicin on metformin PKs and its glucose‐lowering effect in patients with diabetic TB by measuring plasma metformin and blood glucose during and after TB treatment. Rifampicin increased metformin exposure: plasma area under the plasma concentration‐time curve from time point 0 to the end of the dosing interval (AUC 0–τ) and peak plasma concentration (Cmax) geometric mean ratio (GMR; during vs. after TB treatment) were 1.28 (90% confidence interval (CI) 1.13–1.44) and 1.19 (90% CI 1.02–1.38; n = 22). The metformin glucose‐lowering efficacy did not change (Δglucose − Cmax; P = 0.890; n = 18). Thus, we conclude that additional glucose monitoring in this population is not warranted. Finally, 57% of patients on metformin and rifampicin, and 38% of patients on metformin alone experienced gastrointestinal adverse effects. Considering this observation, we advise patients to take metformin and rifampicin with food and preferably separated in time. Clinicians could consider metoclopramide if gastrointestinal adverse effects occur.

200. Clinical trial of metformin to treat preterm preeclampsia: pharmacokinetics and biomarker studies

Introduction Metformin is a potential therapeutic for preeclampsia as it decreases sFlt-1 and soluble endoglin and rescues endothelial dysfunction. Metformin pharmacokinetics in preeclampsia, where there is increased renal clearance and proteinuria, has not been established. Objective/Hypothesis To evaluate metformin XR (extended release) pharmacokinetics in preterm preeclampsia, obtain data on pregnancy prolongation and circulating levels of biomarkers associated with endothelial dysfunction. Methods 15 women with preterm preeclampsia were treated with 1.5 g metformin XR twice daily. Pharmacokinetic sampling was performed on day 1 at 2,4,5,6,7,8,24 h, and concentrations measured using liquid chromatography-tandem mass spectrometry. Given steady state is reached at 24–48 h, trough concentrations were measured at day 1 and 5 to assess the increase in Cmin over time. Plasma was taken twice weekly and biomarkers of endothelial dysfunction measured. Results Gestation at recruitment ranged from 27 to 31 weeks, and median prolongation was 11.5 days [IQR 5.8–23.8]. Pharmacokinetic studies confirmed excellent circulating levels at 0–12 h exposure, with Cmax [median (IQR)] 1.6 (1.3–1.9) mg/l, AUC 0–12 11.7 (8.9–13.5) mg.h/l and AUC 0-infinity 17.0 (10.7–36.6) mg.h/l. Day 1 and 5 trough concentrations were 0.55 (0.34–1.22) mg/l and 0.01 (0.01–0.70) mg/l suggesting steady state exposure is similar to day 1. Umbilical cord blood:plasma ratios taken 4 (3–9.5) hours after dosing were 0.67 (0.2–0.86). None of the following circulating biomarkers increased across pregnancy among those who remain undelivered: sFlt1, soluble endoglin, Vascular Cell Adhesion Molecule 1, Endothelin-1 and placental growth factor. Discussion 1.5 g of metformin XL twice daily in preterm preeclampsia resulted in at least the same exposure as 2 g daily in healthy controls, despite pregnancy and preeclampsia related changes. Metformin potentially stabilised levels of circulating biomarkers of endothelial dysfunction. Randomised trials to treat preterm preeclampsia should be performed.

Increased Metformin Clearance in Overweight and Obese Adolescents: A Pharmacokinetic Substudy of a Randomized Controlled Trial.

BackgroundIn view of the increased use of metformin in obese adolescents, the aim of this study was to determine the pharmacokinetics of metformin in overweight and obese adolescents.MethodsIn overweight and obese adolescents receiving metformin 500 or 1000 mg twice daily for 37 weeks during a clinical trial, blood samples were collected over 8 h during an oral glucose tolerance test. Population pharmacokinetic modeling was performed using NONMEM.ResultsData for 22 overweight and obese adolescents with a mean total body weight (TBW) of 79.3 kg (range 54.7–104.9), body mass index (BMI) of 29.1 kg/m2 (range 22.9–39.3), and age of 15.9 years (range 11.1–17.5) were analysed. In the model, oral clearance (CL/F) of metformin (1.17 l/min [relative standard error of 6%]) increased significantly with TBW (p < 0.01). More specifically, CL/F increased with both developmental weight (WTfor age and length) and excess body weight (WTexcess), for which an excess weight covariate model was proposed.ConclusionThe CL/F of metformin in obese adolescents (1.17 l/min) is larger than that in non-obese children (0.55 l/min) and similar to that in adults (1.3 l/min) as reported in the literature. This increase may potentially be explained by increased tubular secretion of metformin. These results appear to indicate that adult dosages of metformin could be considered in obese adolescents if pediatric dosages have been therapeutically ineffective.ClinicalTrials.govNCT01487993.Electronic supplementary materialThe online version of this article (10.1007/s40272-018-0293-1) contains supplementary material, which is available to authorized users.

Prediction of the Effects of Renal Impairment on Clearance for Organic Cation Drugs that Undergo Renal Secretion: A Simulation-Based Study.

Renal impairment (RI) is a major health concern with a growing prevalence. RI leads to various physiologic changes, in addition to a decrease in glomerular filtration rate, that impact the pharmacokinetics (PK) and, specifically, the renal clearance (CLR) of compounds, including alterations of drug transporter (DT)/drug-metabolizing enzyme expression and activity, as well as protein binding. The objectives of this study were to use a physiologically based pharmacokinetic modeling platform to 1) assess the impact of alterations in DT expression, toxin-drug interactions (TDIs), and free fraction (fu) on PK predictions for the organic cation transporter 2/multidrug and toxin extrusion protein 1 substrate metformin in RI populations; and 2) use available in vitro data to improve predictions of CLR for two actively secreted substrates, metformin and ranitidine. The goal was to identify changes in parameters other than glomerular filtration rate-namely, fu and DT expression/activity-that are consistent with in vitro and clinical data in RI, and predict the importance of these parameters in the PK of metformin and ranitidine in RI patients. Our results demonstrated that including alterations in DT expression and fu, and including TDIs affecting DT activity, as indicated by in vitro data, improved the simulated predictions of CLR and other PK parameters for both metformin and ranitidine in RI. Our simulations suggest that modifications of DT expression/activity and fu are necessary for improved predictions of CLR in RI for compounds that are actively secreted, and that improvement of PK predictions in RI populations for metformin and ranitidine can be obtained by incorporating in vitro data.

Influence of pharmacogenetic polymorphisms and demographic variables on metformin pharmacokinetics in an admixed Brazilian cohort.

To identify pharmacogenetic and demographic variables that influence the systemic exposure to metformin in an admixed Brazilian cohort. The extreme discordant phenotype was used to select 106 data sets from nine metformin bioequivalence trials, comprising 256 healthy adults. Eleven single-nucleotide polymorphisms in SLC22A1, SLC22A2, SLC47A1 SLC47A2 and in transcription factor SP1 were genotyped and a validated panel of ancestry informative markers was used to estimate the individual proportions of biogeographical ancestry. Two-step (univariate followed by multivariate) regression modelling was developed to identify covariates associated with systemic exposure to metformin, accessed by the area under the plasma concentration-time curve, between 0 and 48h (AUC0-48h ), after single oral doses of metformin (500 or 1000mg). The individual proportions of African, Amerindian and European ancestry varied widely, as anticipated from the structure of the Brazilian population The dose-adjusted, log-transformed AUC0-48h 's (nghml-1 mg-1 ) differed largely in the two groups at the opposite ends of the distribution histogram, namely 0.82, 0.79-0.85 and 1.08, 1.06-1.11 (mean, 95% confidence interval; P=6.10-26 , t test). Multivariate modelling revealed that metformin AUC0-48h increased with age, food and carriage of rs12208357 in SLC22A1 but was inversely associated with body surface area and individual proportions of African ancestry. A pharmacogenetic marker in OCT1 (SLC22A1 rs12208357), combined with demographic covariates (age, body surface area and individual proportion of African ancestry) and a food effect explained 29.7% of the variability in metformin AUC0-48h .

Effect of plasma membrane monoamine transporter genetic variants on pharmacokinetics of metformin in humans.

Metformin, an oral hypoglycemic agent belonging to biguanide class, is widely used to treat type 2 diabetes mellitus, and several drug transporters such as organic cation transporters (OCTs), multidrug and toxin extrusion transporter (MATE), and plasma membrane monoamine transporter (PMAT) are thought to affect its disposition. We evaluated the role of PMAT genetic variations on the pharmacokinetic characteristics of metformin in a Korean population. In this retrospective study, 91 healthy subjects from four different metformin pharmacokinetic studies were analyzed; in each study, the subjects were administered two oral doses of metformin at intervals of 12 hours and dose-normalized pharmacokinetic parameters were compared between the subjects' genotypes. Subjects who had more than one allele of c.883-144A>G single nucleotide polymorphism (SNP) in PMAT gene (rs3889348) showed increased renal clearance of metformin compared to wild-type subjects (814.79 ± 391.73 vs. 619.90 ± 195.43 mL/min, p=0.003), whereas no differences in metformin exposure were observed between the PMAT variant subjects and wild-type subjects. Similarly, subjects with variant rs316019 SNP in OCT2 showed decreased renal clearance of metformin compared to wild-type subjects (586.01 ± 160.54 vs. 699.13 ± 291.40 mL/min, p=0.048). Other SNPs in PMAT and MATE1/2-K genes did not significantly affect metformin pharmacokinetics. In conclusion, the genetic variation of c.883-144A>G SNP in PMAT significantly affects the renal clearance of metformin in healthy Korean male subjects.