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.
Humans ; Metformin/pharmacokinetics* ; Diabetes Mellitus, Type 2/metabolism* ; Hypoglycemic Agents/pharmacology* ; AMP-Activated Protein Kinases/metabolism* ; Aging

Ovarian cancer is the seventh most common cancer and the eighth most common cause of cancer mortality in women. Although standard chemotherapy is the established treatment for ovarian cancer, the prognosis remains poor, and it is highly anticipated that new drugs will be developed. New drugs, such as humanized anti-vascular endothelial growth factor monoclonal antibodies and poly ADP-ribose polymerase inhibitors, are expected to improve clinical outcomes of ovarian cancer. However, long-term, costly research is required to develop such new drugs, and soaring national healthcare costs are becoming a concern worldwide. In this social context, drug repositioning, wherein existing drugs are used to develop drugs with new indications for other diseases, has recently gained attention. Because trials have already confirmed the safety in humans and the pharmacokinetics of such drugs, the development period is shorter than the conventional development of a new drug, thereby reducing costs. This review discusses the available basic experimental and clinical data on drugs used for other types of cancer for which drug repositioning is anticipated to repurpose the drug for the treatment of ovarian cancer. These include statins, which are used to treat dyslipidemia; bisphosphonate, which is used to treat osteoporosis; metformin, which is used to treat diabetes; non-steroidal anti-inflammatory drugs; ivermectin, an antiparasitic agent; and itraconazole, an anti-fungal agent. These drugs will play an important role in future drug repositioning strategies for ovarian cancer. Furthermore, drug repositioning is anticipated to extend not only to ovarian cancer treatment but also to ovarian cancer prevention.
Adenosine Diphosphate Ribose ; Anti-Inflammatory Agents, Non-Steroidal ; Antibodies, Monoclonal ; Drug Repositioning* ; Drug Therapy ; Dyslipidemias ; Endothelial Growth Factors ; Female ; Health Care Costs ; Humans ; Hydroxymethylglutaryl-CoA Reductase Inhibitors ; Itraconazole ; Ivermectin ; Metformin ; Mortality ; Osteoporosis ; Ovarian Neoplasms* ; Pharmacokinetics ; Prognosis

Metformin, an oral antihyperglycemic agent, is widely used as the first-line pharmacotherapy for type 2 diabetes mellitus (T2DM). It has been in use for several decades as numerous different formulations. However, despite its use, population pharmacokinetic (PK) modeling of metformin is not well developed. The aim of the present study was to evaluate the effect of formulation on PK parameters by developing a population PK model of metformin in Koreans and using this model to assess bioequivalence. We used a comparative PK study of a single agent and a fixed-dose combination of metformin in 36 healthy volunteers. The population PK model of metformin was developed using NONMEM (version 7.3). Visual predictive checks and bootstrap methods were performed to determine the adequacy of the model. The plasma concentration-time profile was best described by a two-compartment, first-order elimination model with first-order absorption followed by zeroorder absorption with lag time. From the covariate analysis, formulation had significant effect (p < 0.01) on relative bioavailability (F = 0.94) and first-order absorption constant (Ka = 0.83), but the difference was within the range of bioequivalence criteria. No other covariate was shown to have significant effect on PK parameters. The PK profile of the disposition phase was consistent with the published literature. However, in the present study, the multiple peaks found during the absorption phase implied the possible diversity of absorption PK profile depending on formulation or population. Unlike traditional bioequivalence analysis, the population PK model reflects formulation differences on specific parameters and reflected simulation can be performed.
Absorption ; Adult ; Biological Availability ; Diabetes Mellitus, Type 2 ; Drug Therapy ; Healthy Volunteers ; Humans ; Metformin ; Pharmacokinetics ; Plasma ; Therapeutic Equivalency

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.
Alleles ; Cell Membrane ; Diabetes Mellitus, Type 2 ; Genetic Variation ; Genotype ; Healthy Volunteers ; Humans ; Male ; Metformin ; Pharmacokinetics ; Plasma ; Polymorphism, Single Nucleotide ; Retrospective Studies

BACKGROUND: The new type of diabetes treatment, SGLT2 inhibitors, has been approved for monotherapy and combination therapy, but medical insurance is only allowed in combination therapy with metformin, which is the first choice for type 2 diabetes treatment. METHODS: The SGLT2 inhibitors prescribed in Korea are dapagliflozin, empagliflozin and ipragliflozin. A review was conducted using Pubmed to evaluate efficacy and safety for these medications with metformin combination therapy. 10 studies were selected by searching for keywords and related references and were reviewed in full. The mechanism of action, pharmacokinetics, and the economics of treatment with SGLT2 inhibitors were examined. RESULTS: SGLT2 inhibitors had moderate glycemic control when added to the treatment of patients with type 2 diabetes who were not being regulated by metformin monotherapy. They also showed positive effects such as weight loss, as well as the lowering of blood pressure. Hypotension and serious side effects were relatively low. However, the risk of genital infection was increased. CONCLUSION: The SGLT2 inhibitors are a new class of drugs that promote glucose excretion in the urine. They are a good choice for combination therapy with metformin for the treatment of type 2 diabetes, with weight loss and very low risk of serious side effects.
Blood Pressure ; Glucose ; Humans ; Hypotension ; Insurance ; Korea ; Metformin* ; Pharmacokinetics ; Weight Loss

BACKGROUND: In type 2 diabetes mellitus therapy, fixed-dose combination (FDC) can offer not only benefits in glucose control via the combined use of agents, but also increase patient compliance. The aim of this study was to assess the pharmacokinetic equivalence of the high dose of the FDC tablet (gemigliptin/metformin sustained release [SR] 50/1,000 mg) and a corresponding co-administered dose of individual tablets. METHODS: This study was randomized, open-label, single dose, two treatments, two-period, crossover study, which included 24 healthy subjects. Subjects received the FDC or individual tablets of gemigliptin (50 mg) and metformin XR (1,000 mg) in each period. Geometric mean ratios (GMRs) and 90% confidence intervals (CIs) of maximum plasma concentration (Cmax) and area under the plasma concentration-time curve from time zero to the time of the last quantifiable concentration (AUClast) of the FDC tablet and co-administration of individual tablet for both gemigliptin and metformin were calculated. RESULTS: The GMRs (FDC tablets/co-administration; 90% CIs) for Cmax and AUClast of gemigliptin were 1.079 (0.986–1.180) and 1.047 (1.014–1.080), respectively. For metformin, the GMRs for Cmax, and AUClast were 1.038 (0.995–1.083) and 1.041 (0.997–1.088), respectively. The 90% CIs for GMRs of Cmax and AUClast for gemigliptin and metformin fell entirely within bounds of 0.800–1.250. Both administration of FDC tablet and co-administration of individual tablets were well tolerated. CONCLUSION: FDC tablet exhibited pharmacokinetic equivalence and comparable safety and tolerability to co-administration of corresponding doses of gemigliptin and metformin XR as individual tablets. Trial registry at ClinicalTrials.gov, NCT02056600.
Cross-Over Studies ; Diabetes Mellitus, Type 2 ; Glucose ; Healthy Volunteers* ; Metformin* ; Patient Compliance ; Pharmacokinetics ; Plasma ; Tablets*

Two separate studies were conducted to establish bioequivalence (BE) for two doses of atorvastatin/metformin sustained-release (SR) fixed dose combination (FDC) versus the same dosage of the individual component (IC) tablets in healthy male subjects under fed conditions (study 1, BE of atorvastatin/metformin SR 20/500 mg FDC; study 2, BE of atorvastatin/metformin SR 20/750 mg FDC). Each study was a randomized, open-label, single oral dose, two-way crossover design. Serial blood samples were collected pre-dose and up to 36 hours post-dose for atorvastatin and 24 hours for metformin. Plasma concentrations of atorvastatin, 2-OH atorvastatin and metformin were analyzed using a validated liquid chromatography tandem mass-spectrometry. A non-compartmental analysis was used to calculate pharmacokinetic (PK) variables and analysis of variance was performed on the lognormal-transformed PK variables. A total of 75 subjects completed the study 1 (36 subjects) and study 2 (39 subjects). The 90% confidence intervals for the adjusted geometric mean ratio of Cmax and the AUC0-t were within the predefined 0.80 to 1.25 range. The number of subjects reporting at least one adverse event following FDC treatments was comparable to that following IC treatments. The two treatments were well tolerated. Therefore, atorvastatin/metformin SR 20/500 mg and 20/750 mg FDC tablets are expected to be used as alternatives to IC tablets to decrease the pill burden and increase patient compliance.
Atorvastatin Calcium* ; Chromatography, Liquid ; Cross-Over Studies* ; Humans ; Male* ; Metformin* ; Patient Compliance ; Pharmacokinetics* ; Plasma ; Tablets* ; Therapeutic Equivalency

OBJECTIVETo investigate the effect of Musa sapientum L. (MS) bark juice in diabetic gastroparesis and its effect on pharmacokinetic of metformin (MET).

METHODSDiabetes was induced in rats by administering alloxan (120 mg/kg) saline solution and maintained for 8 week. All the 18 Sprague-Dawley rats were divided into three groups (n =6 in each group): normal control, diabetic control and MS bark juice. Assessment of diabetes was done by glucose oxidase-peroxidase method on the 3rd day of alloxan administration. The effects of MS bark juice (100 mL/kg) on gastric emptying time, intestinal transit time, contractility of fundus and pylorus as well as gastric acid secretion in chronic diabetic rats were observed after 8 weeks of alloxan administration. The effect of MS bark juice on the pharmacokinetic of orally administered single dose of MET (350 mg/kg) was evaluated on the 57th day of protocol. Any drugs that may reduce the blood glucose level or influence the fibrinolytic system were not used in this study.

RESULTSThe MS bark juice significantly reduced the blood glucose level in the diabetic rats (P<0.01). There was significant decrease in the pylorus motility and increase in the gastric emptying time, intestinal transit time, contractility of fundus, gastric acid secretion in the MS bark juice treated group (P<0.01). There was significant decrease in the time at which drug at a maximum concentration, half life of drug and increase in the maximum concentration of drug in the plasma of MET in MS bark juice treated group as compared to diabetic control group (P<0.01).

CONCLUSIONMS bark juice effectively manages diabetic gastroparesis and thereby improves the bioavailabilty of MET when administered with MS bark juice.

Alloxan ; Animals ; Blood Glucose ; Chromatography, High Pressure Liquid ; Diabetes Mellitus, Experimental ; blood ; complications ; drug therapy ; physiopathology ; Gastroparesis ; blood ; complications ; drug therapy ; physiopathology ; Male ; Metformin ; blood ; pharmacokinetics ; therapeutic use ; Musa ; chemistry ; Plant Extracts ; pharmacology ; therapeutic use ; Rats, Sprague-Dawley

A simple, sensitive, selective, and reproducible liquid chromatography-tandem mass spectrometric method was developed for the simultaneous determination of repaglinide and metformin in human plasma using d5-repaglinide and d6-metformin as internal standards (ISs). After a simple protein precipitation using acetonitrile as the precipitation solvent, both analytes and ISs were separated on a Venusil ASB C 18 (150 mm x 4.6 mm, 5 microm) via gradient elution using acetonitrile--10 mmol x L(-1) ammonium acetate as the mobile phase. A chromatographic total run time of 7.5 min was achieved. Mass spectrometric detection was conducted with atmospheric pressure chemical ionization under positive-ion and multiple-reaction monitoring modes. The method was linear over the 0.2 to 60.0 ng x mL(-1) concentration range for repaglinide and over the 4 to 1 000 ng x mL(-1) range for metformin. For both analytes, the intra- and inter-accuracies and precisions were within the +/- 15% acceptable limit across all concentrations. The validated method was successfully applied to a clinical bioequivalence study.
Administration, Oral ; Adolescent ; Adult ; Area Under Curve ; Carbamates ; administration & dosage ; blood ; pharmacokinetics ; Chromatography, Liquid ; Drug Stability ; Female ; Humans ; Hypoglycemic Agents ; administration & dosage ; blood ; pharmacokinetics ; Male ; Metformin ; administration & dosage ; blood ; pharmacokinetics ; Middle Aged ; Piperidines ; administration & dosage ; blood ; pharmacokinetics ; Tandem Mass Spectrometry ; Therapeutic Equivalency ; Young Adult

The present study was to estimate pharmacokinetic parameters of metformin hydrochloride in 20 Chinese healthy volunteers with a limited sampling strategy (LSS), which will provide scientific data for bioequivalence and clinical application. A single dose of metformin was administrated to 20 healthy volunteers. The concentration of metformin in whole blood was determined by validated high performance liquid chromatography (HPLC) method. Multi-linear regression analysis was performed to establish a model to estimate AUC(0-24 h) and Cmax of metformin by LSS method. The LSS models were validated by the Jackknife method. The result indicated: the linearity relationship between AUC(0-24 h) or Cmax and single concentration point was poor. Several models for metformin AUC(0-24 h) or Cmax, estimation were better (r2 > 0.9, P < 0.05). Validation tests indicated that most informative sampling points (C2, C6 for AUC(0-24 h), C1.5, C2 for Cmax) provided accurate estimations of these parameters. So, a multi-linear regression model for estimation pharmacokinetic parameters of metformin by using LSS method is feasible.
Adult ; Area Under Curve ; Chromatography, High Pressure Liquid ; methods ; Humans ; Hypoglycemic Agents ; administration & dosage ; pharmacokinetics ; Linear Models ; Male ; Metformin ; administration & dosage ; pharmacokinetics ; Sample Size ; Therapeutic Equivalency ; Young Adult