Clinical pharmacokinetics of metformin

Metformin enhances epithelial cell growth inhibition via the protein kinase-insulin-like growth factor binding protein-1 pathway

BACKGROUND

Abnormal stromal-epithelial cell communication is a pathogenic mechanism in endometriosis, and metformin can modulate it. Insulin-like growth factor binding protein-1 (IGFBP1) plays a role in endometriosis, but the exact mechanism is unknown. IGFBP1 is reportedly a downstream target of metformin in some diseases. We aimed to investigate the role of IGFBP1 in endometriosis development, whether it is associated with abnormal communication, and whether metformin affects IGFBP1 expression.

METHODS

Patients who underwent surgical treatment for endometriosis or other diseases were enrolled. Ten patients with ovarian-type endometriosis and eight patients each who underwent surgical treatment for other lesions with or without endometriosis were selected, and their tissues taken for cell proliferation, western blotting, polymerase chain reaction, and knockdown experiments.

RESULTS

Ectopic and eutopic stromal cells (EcSCs and EuSCs) lost their ability to inhibit epithelial cell proliferation, and IGFBP1 expression was downregulated in both groups of stromal cells compared to that in normal stromal cells (NSCs; 1.09 vs. 0.25, p = .0002 1.09 vs. 0.57, p = .0029). In an EcSC IGFBP1 overexpression model, the ability of EcSCs to inhibit epithelial cell proliferation was enhanced (EdU positivity decreased from 38% to 25%, p = .0001). Furthermore, adenosine 5'-monophosphate-activated protein kinase (AMPK) phosphorylation was downregulated in EcSCs and EuSCs compared to that in NSCs (0.99 vs. 0.42, p = .0006/0.99 vs. 0.57, p = 0.0032). Treatment of EcSCs with metformin increased AMPK phosphorylation (0.47 vs. 1.04, p = .0107) while upregulating IGFBP1 expression (0.69 vs. 1.01, p = .0164), whereas pre-treatment with an AMPK phosphorylation inhibitor abrogated metformin-induced IGFBP1 upregulation.

CONCLUSIONS

IGFBP1 mediates aberrant stromal-epithelial communication in endometriosis. Metformin can upregulate IGFBP1 expression in EcSCs by activating AMPK, and upregulated IGFBP1 enhances the inhibition of epithelial cell proliferation. IGFBP1 is expected to be a therapeutic target for endometriosis.

Effects and interaction of single nucleotide polymorphisms at the pharmacokinetic/pharmacodynamic site: insights from the Rotterdam study into metformin clinical response and dose titration

Our study investigated the impact of genetic variations on metformin glycemic response in a cohort from the Rotterdam Study, comprising 14,926 individuals followed for up to 27 years. Among 1285 metformin users of European ancestry, using linear mixed models, we analyzed the association of single nucleotide polymorphisms (SNPs) and a Polygenic Risk Score (PRS) with glycemic response, measured by changes in metformin dosage or HbA1c levels. While individual genetic variants showed no significant association, rs622342 on SLC2A1 correlated with increased glycemic response only in metformin monotherapy patients (β = -2.09, P-value < 0.001). The collective effect of variants, as represented by PRS, weakly correlated with changes in metformin dosage (β = 0.023, P-value = 0.027). Synergistic interaction was observed between rs7124355 and rs8192675. Our findings suggest that while higher PRS correlates with increased metformin dosage, its modest effect size limits clinical utility, emphasizing the need for future research in diverse populations to refine genetic risk models.

Electroporation enhances cell death in 3D scaffold-based MDA-MB-231 cells treated with metformin

Triple-negative breast cancer (TNBC), the most aggressive subtype of breast cancer lacks estrogen, progesterone, and HER2 receptors and hence, is therapeutically challenging. Towards this, we studied an alternate therapy by repurposing metformin (FDA-approved type-2 diabetic drug with anticancer properties) in a 3D-scaffold culture, with electrical pulses. 3D cell culture was used to simulate the tumor microenvironment more closely and MDA-MB-231, human TNBC cells, treated with both 5 mM metformin (Met) and 8 electrical pulses at 2500 V/cm, 10 µs (EP1) and 800 V/cm, 100 µs (EP2) at 1 Hz were studied in 3D and 2D. They were characterized using cell viability, reactive oxygen species (ROS), glucose uptake, and lactate production assays at 24 h. Cell viability, as low as 20 % was obtained with EP1 + 5 mM Met. They exhibited 1.65-fold lower cell viability than 2D with EP1 + 5 mM Met. ROS levels indicated a 2-fold increase in oxidative stress for EP1 + 5 mM Met, while the glucose uptake was limited to only 9 %. No significant change in the lactate production indicated glycolytic arrest and a non-conducive environment for MDA-MB-231 growth. Our results indicate that 3D cell culture, with a more realistic tumor environment that enhances cell death using metformin and electrical pulses could be a promising approach for TNBC therapeutic intervention studies.

Metformin in combination with chemotherapy increases apoptosis in gastric cancer cells and counteracts senescence induced by chemotherapy

Gastric cancer (GC) is the fourth leading cause of cancer death in the world, and there is a demand for new therapeutic agents to treat GC. Metformin has been demonstrated to be an antineoplastic agent in some types of cancer; however, it has not been sufficiently valued in treating GC because the effect of metformin in combination with chemotherapy regimens has not yet been evaluated. The present study aimed to evaluate the mechanisms underlying cell death induced by metformin alone or when combined with chemotherapy. The cytogenetic characteristics of the NCI-N87 cell line were determined by fluorescence in situ hybridization (FISH). To determine viability, the cells were treated with metformin, epirubicin, cisplatin, docetaxel and 5-fluorouracil (individually and at different concentrations). Subsequently, the cells were treated with metformin alone, and in combination with the chemotherapeutic drugs and the epirubicin + cisplatin + 5-fluorouracil, docetaxel + cisplatin + 5-fluorouracil, and cisplatin + 5-fluorouracil regimens. Cell viability, proliferation and mitochondrial membrane potential (ΔΨm) were analyzed by spectrophotometry. Apoptosis, caspase activity and cell cycle progression were assessed by flow cytometry. Finally, light microscopy was used to evaluate senescence and clonogenicity. The results revealed that metformin, alone and when combined with chemotherapy, increased the proportion of apoptotic cells, promoted the loss of ΔΨm, and induced apoptosis through caspase activity in GC cells. Moreover, metformin decreased cell proliferation. In addition, metformin alone did not induce senescence and it counteracted the effects of chemotherapy-induced senescence in GC cells. Additionally, metformin, alone and when combined with chemotherapy, decreased the clonogenic capacity of NCI-N87 GC cells. In conclusion, metformin may increase the effects of chemotherapy on NCI-N87 cell death and could represent an option to improve the treatment of GC.

Computational Screening of Hydrophobic Zeolites for the Removal of Emerging Organic Contaminants from Water

The pollution of water resources by pharmaceuticals and agents of personal care products (PPCPs) poses an increasingly pressing issue that has received considerable attention from scientists and government agencies alike. Hydrophobic zeolites can serve as selective adsorbents to remove these contaminants from aqueous solution. So far, the adsorption of PPCPs in zeolites has often been investigated in case studies focusing on a small number of contaminants and one or a few zeolites. We present a computational screening approach to investigate the interaction of 53 PPCPs with 14 all-silica zeolites, aiming at a more comprehensive understanding of factors that are beneficial for a strong host-guest interaction and thus an efficient adsorption. The systems are modelled on the classical force field level of theory, allowing for the efficient computational treatment of a large number of PPCP-zeolite combinations and evaluated in terms of the interaction energy between PPCP and zeolite framework. For selected PPCP-zeolite combinations additional Free Energy Perturbation simulations are employed to compute Free Energies of Transfer between the aqueous phase and the adsorbed state. These results can serve as a starting point for experimental studies of relevant PPCP-zeolite combination or more in-depth theoretical investigations.

Metformin impacts the differentiation of mouse bone marrow cells into macrophages affecting tumour immunity

Background

Epidemiological studies suggest that metformin reduces the risk of developing several types of cancer, including gliomas, and improves the overall survival in cancer patients. Nevertheless, while the effect of metformin on cancer cells has been extensively studied, its impact on other components of the tumour microenvironment, such as macrophages, is less understood.

Results

Metformin-treated mouse bone marrow cells differentiate into spindle-shaped macrophages exhibiting increased phagocytic activity and tumour cell cytotoxicity coupled with modulated expression of co-stimulatory molecules displaying reduced sensitivity to inflammatory cues compared with untreated cells. Transcriptional analyses of metformin-treated mouse bone marrow-derived macrophages show decreased expression levels of pro-tumour genes, including Tgfbi and Il1β, related to enhanced mTOR/HIF1α signalling and metabolic rewiring towards glycolysis.

Significance

Our study provides novel insights into the immunomodulatory properties of metformin in macrophages and its potential application in preventing tumour onset and in cancer immunotherapy.

Emerging Human Medications in Racing Animals: Analytical and Regulatory Challenges

Positive identification and reporting of therapeutic substances intended for human consumption in race-day equine and canine samples is a controversial topic. While inadvertent environmental exposure is a potential cause for the presence of these substances in race-day samples, intentional use cannot be ruled out given their therapeutic benefits. Pregabalin is widely prescribed in Australia to treat epilepsy, anxiety, and neuropathic pain in humans; however, it is also increasingly used as a recreational drug. Metformin is commonly used to treat type 2 diabetes in humans. Both pregabalin and metformin have no routine use on racing animals and should not be present in race-day samples taken from healthy animals. They are prohibited substances under the Rules of Racing with no established screening limits. Although therapeutic levels for these substances have been established in humans, such information is not available for animals. Pregabalin and metformin are analytically challenging molecules, more so when they are extracted from biological matrices routinely screened for hundreds of other compounds simultaneously. A simple extraction, followed by a targeted Ultra High-Pressure Liquid Chromatography Orbitrap™ Mass Spectrometry method utilising a reverse-phase C18 column, is presented. This method is effective in screening for pregabalin and metformin, in addition to more than 150 other compounds of interest in equine and canine urines. The prevalence of pregabalin and metformin in race-day equine and canine urine samples in Western Australia was monitored using this method over 12 months. More than 4000 urine samples were screened, and four samples were confirmed positive for these substances.

Metformin hydrolase is a recently evolved nickel-dependent heteromeric ureohydrolase

The anti-diabetic drug metformin is one of the most widely prescribed medicines in the world. Together with its degradation product guanylurea, it is a major pharmaceutical pollutant in wastewater treatment plants and surface waters. An operon comprising two genes of the ureohydrolase family in Pseudomonas and Aminobacter species has recently been implicated in metformin degradation. However, the corresponding proteins have not been characterized. Here we show that these genes encode a Ni2+-dependent enzyme that efficiently and specifically hydrolyzes metformin to guanylurea and dimethylamine. The active enzyme is a heteromeric complex of α- and β- subunits in which only the α-subunits contain the conserved His and Asp residues for the coordination of two Ni2+ ions in the active site. A crystal structure of metformin hydrolase reveals an α2β4 stoichiometry of the hexameric complex, which is unprecedented in the ureohydrolase family. By studying a closely related but more widely distributed enzyme, we find that the putative predecessor specifically hydrolyzes dimethylguanidine instead of metformin. Our findings establish the molecular basis for metformin hydrolysis to guanylurea as the primary pathway for metformin biodegradation and provide insight into the recent evolution of ureohydrolase family proteins in response to an anthropogenic compound.

Metformin decelerates aging clock in male monkeys

In a rigorous 40-month study, we evaluated the geroprotective effects of metformin on adult male cynomolgus monkeys, addressing a gap in primate aging research. The study encompassed a comprehensive suite of physiological, imaging, histological, and molecular evaluations, substantiating metformin's influence on delaying age-related phenotypes at the organismal level. Specifically, we leveraged pan-tissue transcriptomics, DNA methylomics, plasma proteomics, and metabolomics to develop innovative monkey aging clocks and applied these to gauge metformin's effects on aging. The results highlighted a significant slowing of aging indicators, notably a roughly 6-year regression in brain aging. Metformin exerts a substantial neuroprotective effect, preserving brain structure and enhancing cognitive ability. The geroprotective effects on primate neurons were partially mediated by the activation of Nrf2, a transcription factor with anti-oxidative capabilities. Our research pioneers the systemic reduction of multi-dimensional biological age in primates through metformin, paving the way for advancing pharmaceutical strategies against human aging.

Rethinking about Metformin: Promising Potentials

Metformin is widely used drugs in the treatment of type 2 diabetes mellitus. However, the mechanisms of action are complex and are still not fully understood yet. Metformin has a dose-dependent blood sugar-lowering effect. The most common adverse reactions of metformin are gastrointestinal symptoms, and women tend to be more experienced than men. A positive correlation between the administration of duration and the daily dose of metformin and the risk of vitamin B12 deficiency is confirmed. Novel glucose-lowering mechanism through the activation of AMP-activated protein kinase and alteration of gut microbiota composition is identified. In addition, metformin has immunomodulatory properties in various mechanisms, including anti-inflammatory actions, and so forth. Metformin improves insulin sensitivity, which may reduce the risk of tumor growth in certain cancers. The antiviral effects of metformin may occur through several mechanisms, including blocking angiotensin converting enzyme 2 receptor, and so forth. These potential mechanisms of metformin are promising in various clinical settings, such as inflammatory diseases, autoimmune diseases, cancer, and coronavirus disease 2019.

Vitamin B12 Deficiency in Patients Taking Metformin: Pathogenesis and Recommendations

Metformin is a cornerstone therapy for type 2 diabetes mellitus due to its glucose-lowering efficacy and additional benefits such as reducing cardiovascular mortality. However, accumulating evidence suggests an association between long-term metformin use and vitamin B12 deficiency, which can lead to serious clinical consequences. This review aims to synthesize current knowledge on the pathogenesis, prevalence, clinical implications, and management of metformin-induced vitamin B12 deficiency. Given the significant clinical implications, it is crucial to monitor and manage vitamin B12 levels in patients using metformin. This review emphasizes the importance of early detection and supplementation to prevent adverse outcomes. By analyzing the current evidence, the review aims to inform healthcare professionals about best practices for managing vitamin B12 deficiency in patients on metformin, offering insights to guide future clinical practices and research directions.

Emerging role of Metformin in Alzheimer's disease: A translational view

Alzheimer's disease (AD) constitutes a major public-health issue of our time. Regrettably, despite our considerable understanding of the pathophysiological aspects of this disease, current interventions lead to poor outcomes. Furthermore, experimentally promising compounds have continuously failed when translated to clinical trials. Along with increased population ageing, Type 2 Diabetes Mellitus (T2DM) has become an extremely common condition, mainly due to unbalanced dietary habits. Substantial epidemiological evidence correlates T2DM with cognitive impairment as well. Considering that brain insulin resistance, mitochondrial dysfunction, oxidative stress, and amyloidogenesis are common phenomena, further approaching the common features among these pathological conditions. Metformin constitutes the first-choice drug to preclude insulin resistance in T2DM clinical management. Experimental evidence suggests that its functions might include neuroprotective effects, in addition to its hypoglycemic activity. This review aims to summarize and discuss current knowledge of experimental data on metformin on this path towards translational medicine. Finally, we discuss the controversial data of responses to metformin in vitro, and in vivo, animal models and human studies.

AMPK activation reduces cancer cell aggressiveness via inhibition of monoamine oxidase A (MAO-A) expression/activity

AIM

AMPK can be considered as an important target molecule for cancer for its unique ability to directly recognize cellular energy status. The main aim of this study is to explore the role of different AMPK activators in managing cancer cell aggressiveness and to understand the mechanistic details behind the process.

MAIN METHODS

First, we explored the AMPK expression pattern and its significance in different subtypes of lung cancer by accessing the TCGA data sets for LUNG, LUAD and LUSC patients and then established the correlation between AMPK expression pattern and overall survival of lung cancer patients using Kaplan-Meire plot. We further carried out several cell-based assays by employing different wet lab techniques including RT-PCR, Western Blot, proliferation, migration and invasion assays to fulfil the aim of the study.

KEY FINDINGS

SIGNIFICANCE: This study identifies the importance of AMPK activators as a repurposing agent for combating lung and colon cancer cell aggressiveness. It also suggests SRT-1720 as a potent repurposing agent for cancer treatment especially in NSCLC patients where a point mutation is present in LKB1.

Targeting Asparagine Metabolism in Well-Differentiated/Dedifferentiated Liposarcoma

BACKGROUND

mTORC1 activity is dependent on the presence of micronutrients, including Asparagine (Asn), to promote anabolic cell signaling in many cancers. We hypothesized that targeting Asn metabolism would inhibit tumor growth by reducing mTORC1 activity in well-differentiated (WD)/dedifferentiated (DD) liposarcoma (LPS).

METHODS

Human tumor metabolomic analysis was utilized to compare abundance of Asn in WD vs. DD LPS. Gene set enrichment analysis (GSEA) compared relative expression among metabolic pathways upregulated in DD vs. WD LPS. Proliferation assays were performed for LPS cell lines and organoid models by using the combination treatment of electron transport chain (ETC) inhibitors with Asn-free media. 13C-Glucose-labeling metabolomics evaluated the effects of combination treatment on nucleotide synthesis. Murine xenograft models were used to assess the effects of ETC inhibition combined with PEGylated L-Asparaginase (PEG-Asnase) on tumor growth and mTORC1 signaling.

RESULTS

Asn was enriched in DD LPS compared to WD LPS. GSEA indicated that mTORC1 signaling was upregulated in DD LPS. Within available LPS cell lines and organoid models, the combination of ETC inhibition with Asn-free media resulted in reduced cell proliferation. Combination treatment inhibited nucleotide synthesis and promoted cell cycle arrest. In vivo, the combination of ETC inhibition with PEG-Asnase restricted tumor growth.

CONCLUSIONS

Asn enrichment and mTORC1 upregulation are important factors contributing to WD/DD LPS tumor progression. Effective targeting strategies require limiting access to extracellular Asn and inhibition of de novo synthesis mechanisms. The combination of PEG-Asnase with ETC inhibition is an effective therapy to restrict tumor growth in WD/DD LPS.

Modeling Metformin and Dapagliflozin Pharmacokinetics in Chronic Kidney Disease

Chronic kidney disease (CKD) is a complication of diabetes that affects circulating drug concentrations and elimination of drugs from the body. Multiple drugs may be prescribed for treatment of diabetes and co-morbidities, and CKD complicates the pharmacotherapy selection and dosing regimen. Characterizing variations in renal drug clearance using models requires large clinical datasets that are costly and time-consuming to collect. We propose a flexible approach to incorporate impaired renal clearance in pharmacokinetic (PK) models using descriptive statistics and secondary data with mechanistic models and PK first principles. Probability density functions were generated for various drug clearance mechanisms based on the degree of renal impairment and used to estimate the total clearance starting from glomerular filtration for metformin (MET) and dapagliflozin (DAPA). These estimates were integrated with PK models of MET and DAPA for simulations. MET renal clearance decreased proportionally with a reduction in estimated glomerular filtration rate (eGFR) and estimated net tubular transport rates. DAPA total clearance varied little with renal impairment and decreased proportionally to reported non-renal clearance rates. Net tubular transport rates were negative to partially account for low renal clearance compared with eGFR. The estimated clearance values and trends were consistent with MET and DAPA PK characteristics in the literature. Dose adjustment based on reduced clearance levels estimated correspondingly lower doses for MET and DAPA while maintaining desired dose exposure. Estimation of drug clearance rates using descriptive statistics and secondary data with mechanistic models and PK first principles improves modeling of CKD in diabetes and can guide treatment selection.

Pharmacological characterization of the antidiabetic drug metformin in atherosclerosis inhibition: A comprehensive insight

BACKGROUND

Atherosclerosis (AS) is a progressive disease that interferes with blood flow, leading to cardiovascular complications such as hypertension, ischemic heart disease, ischemic stroke, and vascular ischemia. The progression of AS is correlated with inflammation, oxidative stress, and endothelial dysfunction. Various signaling pathways, like nuclear erythroid-related factor 2 (Nrf2) and Kruppel-like factor 2 (KLF2), are involved in the pathogenesis of AS. Nrf2 and KLF2 have anti-inflammatory and antioxidant properties. Thus, activation of these pathways may reduce the development of AS. Metformin, an insulin-sensitizing drug used in the management of type 2 diabetes mellitus (T2DM), increases the expression of Nrf2 and KLF2. AS is a common long-term macrovascular complication of T2DM. Thus, metformin, through its pleiotropic anti-inflammatory effect, may attenuate the development and progression of AS.

AIMS

Therefore, this review aims to investigate the possible role of metformin in AS concerning its effect on Nrf2 and KLF2 and inhibition of reactive oxygen species (ROS) formation. In addition to its antidiabetic effect, metformin can reduce cardiovascular morbidities and mortalities compared to other antidiabetic agents, even with similar blood glucose control by the Nrf2/KLF2 pathway activation.

CONCLUSION

In conclusion, metformin is an effective therapeutic strategy against the development and progression of AS, mainly through activation of the KLF2/Nrf2 axis.

Metformin: Therapeutic profile in the treatment of type 2 diabetes

Metformin (dimethyl-biguanide) can claim its origins in the use of Galega officinalis as a plant treatment for symptoms ascribed to diabetes. Since the first clinical use of metformin as a glucose-lowering agent in 1957, this medicine has emerged as a first-line pharmacological option to support lifestyle interventions in the management of type 2 diabetes (T2D). It acts through multiple cellular pathways, principally in the gut, liver and muscle, to counter insulin resistance and lower blood glucose without weight gain or risk of overt hypoglycaemia. Other effects include improvements in lipid metabolism, decreased inflammation and lower long-term cardiovascular risk. Metformin is conveniently combined with other diabetes medications, can be prescribed in prediabetes to reduce the risk of progression to T2D, and is used in some regions to assist glycaemic control in pregnancy. Consistent with its diversity of actions, established safety profile and cost-effectiveness, metformin is being assessed for further possible clinical applications. The use of metformin requires adequate renal function for drug elimination, and may cause initial gastrointestinal side effects, which can be moderated by taking with meals or using an extended-release formulation. Thus, metformin serves as a valuable therapeutic resource for use throughout the natural history of T2D.

Metformin augments major cytoplasmic organization except for spindle organization in oocytes cultured under hyperglycemic and hyperlipidemic conditions: An in vitro study

The present study aimed to investigate the role of antidiabetic drug metformin on the cytoplasmic organization of oocytes. Germinal vesicle (GV) stage oocytes were collected from adult female Swiss albino mice and subjected to in vitro maturation (IVM) in various experimental groups- control, vehicle control (0.3% ethanol), metformin (50 μg/mL), high glucose and high lipid (HGHL, 10 mM glucose; 150 μM palmitic acid; 75 μM stearic acid and 200 μM oleic acid in ethanol), and HGHL supplemented with metformin. The metaphase II (MII) oocytes were analyzed for lipid accumulation, mitochondrial and endoplasmic reticulum (ER) distribution pattern, oxidative and ER stress, actin filament organization, cortical granule distribution pattern, spindle organization and chromosome alignment. An early polar body extrusion was observed in the HGHL group. However, the maturation rate at 24 h did not differ significantly among the experimental groups compared to the control. The HGHL conditions exhibited significantly higher levels of oxidative stress, ER stress, poor actin filament organization, increased lipid accumulation, altered mitochondrial distribution, spindle abnormalities, and chromosome misalignment compared to the control. Except for spindle organization, supplementation of metformin to the HGHL conditions improved all the parameters (non-significant for ER and actin distribution pattern). These results show that metformin exposure in the culture media helped to improve the hyperglycemia and hyperlipidemia-induced cytoplasmic anomalies except for spindle organization. Given the crucial role of spindle organization in proper chromosome segregation during oocyte maturation and meiotic resumption, the implications of metformin's limitations in this aspect warrant careful evaluation and further investigation.

Energy Metabolism and Metformin: Effects on Ischemia-Reperfusion Injury in Kidney Transplantation

Metformin (MTF) is the only biguanide included in the World Health Organization's list of essential medicines; representing a widespread drug in the management of diabetes mellitus. With its accessibility and affordability being one of its biggest assets, it has become the target of interest for many trying to find alternative treatments for varied pathologies. Over time, an increasing body of evidence has shown additional roles of MTF, with unexpected interactions of benefit in other diseases. Metformin (MTF) holds significant promise in mitigating ischemia-reperfusion injury (IRI), particularly in the realm of organ transplantation. As acceptance criteria for organ transplants expand, IRI during the preservation phase remain a major concern within the transplant community, prompting a keen interest in MTF's effects. Emerging evidence suggests that administering MTF during reperfusion may activate the reperfusion injury salvage kinase (RISK) pathway. This pathway is pivotal in alleviating IRI in transplant recipients, potentially leading to improved outcomes such as reduced rates of organ rejection. This review aims to contextualize MTF historically, explore its current uses, pharmacokinetics, and pharmacodynamics, and link these aspects to the pathophysiology of IRI to illuminate its potential future role in transplantation. A comprehensive survey of the current literature highlights MTF's potential to recondition and protect against IRI by attenuating free radical damage, activating AMP-activated protein kinase to preserve cellular energy and promote repair, as well as directly reducing inflammation and enhancing microcirculation.

Liver Fibrosis Stages Affect Organic Cation Transporter 1/2 Activities in Hepatitis C Virus-Infected Patients

This study aims to evaluate the impact of liver fibrosis stages of chronic infection with hepatitis C virus (HCV) on the in vivo activity of organic cation transporters (hepatic OCT1 and renal OCT2) using metformin (MET) as a probe drug. Participants allocated in Group 1 (n = 15, mild to moderate liver fibrosis) or 2 (n = 13, advanced liver fibrosis and cirrhosis) received a single MET 50 mg oral dose before direct-acting antiviral (DAA) drug treatment (Phase 1) and 30 days after achieving sustained virologic response (Phase 2). OCT1/2 activity (MET AUC0-24) was found to be reduced by 25% when comparing the two groups in Phase 2 (ratio 0.75 (0.61-0.93), p < 0.05) but not in Phase 1 (ratio 0.81 (0.66-0.98), p > 0.05). When Phases 1 and 2 were compared, no changes were detected in both Groups 1 (ratio 1.10 (0.97-1.24), p > 0.05) and 2 (ratio 1.03 (0.94-1.12), p > 0.05). So, this study shows a reduction of approximately 25% in the in vivo activity of OCT1/2 in participants with advanced liver fibrosis and cirrhosis after achieving sustained virologic response and highlights that OCT1/2 in vivo activity depends on the liver fibrosis stage of chronic HCV infection.

Delaying Renal Aging: Metformin Holds Promise as a Potential Treatment

Given the rapid aging of the population, age-related diseases have become an excessive burden on global health care. The kidney, a crucial metabolic organ, ages relatively quickly. While the aging process itself does not directly cause kidney damage, the physiological changes that accompany it can impair the kidney's capacity for self-repair. This makes aging kidneys more susceptible to diseases, including increased risks of chronic kidney disease and end-stage renal disease. Therefore, delaying the progression of renal aging and preserving the youthful vitality of the kidney are crucial for preventing kidney diseases. However, effective strategies against renal aging are still lacking due to the underlying mechanisms of renal aging, which have not been fully elucidated. Accumulating evidence suggests that metformin has beneficial effects in mitigating renal aging. Metformin has shown promising anti-aging results in animal models but has not been tested for this purpose yet in clinical trials. These findings indicate the potential of metformin as an anti-renal aging drug. In this review, we primarily discuss the characteristics and mechanisms of kidney aging and the potential effects of metformin against renal aging.

Comprehensive GC-MS Measurement of Amino Acids, Metabolites, and Malondialdehyde in Metformin-Associated Lactic Acidosis at Admission and during Renal Replacement Treatment

Metformin is the most widely used drug in type 2 diabetes. Regular metformin use has been associated with changes in concentrations of amino acids. In the present study, we used valid stable-isotope labeled GC-MS methods to measure amino acids and metabolites, including creatinine as well as malondialdehyde (MDA), as an oxidative stress biomarker in plasma, urine, and dialysate samples in a patient at admission to the intensive care unit and during renal replacement treatment because of metformin-associated lactic acidosis (MALA, 21 mM lactate, 175 µM metformin). GC-MS revealed lower concentrations of amino acids in plasma, normal concentrations of the nitric oxide (NO) metabolites nitrite and nitrate, and normal concentrations of MDA. Renal tubular reabsorption rates were altered on admission. The patient received renal replacement therapy over 50 to 70 h of normalized plasma amino acid concentrations and their tubular reabsorption, as well as the tubular reabsorption of nitrite and nitrate. This study indicates that GC-MS is a versatile analytical tool to measure different classes of physiological inorganic and organic substances in complex biological samples in clinical settings such as MALA.

Repurposing Metformin for the Treatment of Atrial Fibrillation: Current Insights

Metformin is an orally effective anti-hyperglycemic drug that despite being introduced over 60 years ago is still utilized by an estimated 120 to 150 million people worldwide for the treatment of type 2 diabetes (T2D). Metformin is used off-label for the treatment of polycystic ovary syndrome (PCOS) and for pre-diabetes and weight loss. Metformin is a safe, inexpensive drug with side effects mostly limited to gastrointestinal issues. Prospective clinical data from the United Kingdom Prospective Diabetes Study (UKPDS), completed in 1998, demonstrated that metformin not only has excellent therapeutic efficacy as an anti-diabetes drug but also that good glycemic control reduced the risk of micro- and macro-vascular complications, especially in obese patients and thereby reduced the risk of diabetes-associated cardiovascular disease (CVD). Based on a long history of clinical use and an excellent safety record metformin has been investigated to be repurposed for numerous other diseases including as an anti-aging agent, Alzheimer's disease and other dementias, cancer, COVID-19 and also atrial fibrillation (AF). AF is the most frequently diagnosed cardiac arrythmia and its prevalence is increasing globally as the population ages. The argument for repurposing metformin for AF is based on a combination of retrospective clinical data and in vivo and in vitro pre-clinical laboratory studies. In this review, we critically evaluate the evidence that metformin has cardioprotective actions and assess whether the clinical and pre-clinical evidence support the use of metformin to reduce the risk and treat AF.

Metformin-associated lactic acidosis: A mini review of pathophysiology, diagnosis and management in critically ill patients

Metformin is a common diabetes drug that may reduce lactate clearance by inhibiting mitochondrial oxidative phosphorylation, leading to metformin-associated lactic acidosis (MALA). As diabetes mellitus is a common chronic metabolic condition found in critically ill patients, pre-existing metformin use can often be found in critically ill patients admitted to the intensive care unit or the high dependency unit. The aim of this narrative mini review is therefore to update clinicians about MALA, and to provide a practical approach to its diagnosis and treatment. MALA in critically ill patients may be suspected in a patient who has received metformin and who has a high anion gap metabolic acidosis, and confirmed when lactate exceeds 5 mmol/L. Risk factors include those that reduce renal elimination of metformin (renal impairment from any cause, histamine-2 receptor antagonists, ribociclib) and excessive alcohol consumption (as ethanol oxidation consumes nicotinamide adenine dinucleotides that are also required for lactate metabolism). Treatment of MALA involves immediate cessation of metformin, supportive management, treating other concurrent causes of lactic acidosis like sepsis, and treating any coexisting diabetic ketoacidosis. Severe MALA requires extracorporeal removal of metformin with either intermittent hemodialysis or continuous kidney replacement therapy. The optimal time to restart metformin has not been well-studied. It is nonetheless reasonable to first ensure that lactic acidosis has resolved, and then recheck the kidney function post-recovery from critical illness, ensuring that the estimated glomerular filtration rate is 30 mL/min/1.73 m2 or better before restarting metformin.

Advances in the mechanism of metformin with wide-ranging effects on regulation of the intestinal microbiota

Metformin is of great focus because of its high safety, low side effects, and various effects other than lowering blood sugar, such as anti-inflammation, anti-tumor, and anti-aging. Studies have shown that metformin has a modulating effect on the composition and function of the intestinal microbiota other than acting on the liver. However, the composition of microbiota is complex and varies to some extent between species and individuals, and the experimental design of each study is also different. Multiple factors present a major obstacle to better comprehending the effects of metformin on the gut microbiota. This paper reviews the regulatory effects of metformin on the gut microbiota, such as increasing the abundance of genus Akkermansia, enriching short-chain fatty acids (SCFAs)-producing bacterial genus, and regulating gene expression of certain genera. The intestinal microbiota is a large and vital ecosystem in the human body and is considered to be the equivalent of an "organ" of the human body, which is highly relevant to human health and disease status. There are a lot of evidences that the gut microbiota is responsible for metformin's widespread effects. However, there are only a few systematic studies on this mechanism, and the specific mechanism is still unclear. This paper aims to summarize the possible mechanism of metformin in relation to gut microbiota.

Beneficial effects of metformin treatment on memory impairment

Memory issues are a prevalent symptom in different neurodegenerative diseases and can also manifest in certain psychiatric conditions. Despite limited medications approved for treating memory problems, research suggests a lack of sufficient options in the market. Studies indicate that a significant percentage of elderly individuals experience various forms of memory disorders. Metformin, commonly prescribed for type 2 diabetes, has shown neuroprotective properties through diverse mechanisms. This study explores the potential of metformin in addressing memory impairments. The current research gathered its data by conducting an extensive search across electronic databases including PubMed, Web of Science, Scopus, and Google Scholar. Previous research suggests that metformin enhances brain cell survival and memory function in both animal and clinical models by reducing oxidative stress, inflammation, and cell death while increasing beneficial neurotrophic factors. The findings of the research revealed that metformin is an effective medication for enhancing various types of memory problems in numerous studies. Given the rising incidence of memory disorders, it is plausible to utilize metformin, which is an affordable and accessible drug. It is often recommended as a treatment to boost memory.

Cancer biology in diabetes update: Focusing on antidiabetic drugs

The association of type 2 diabetes with certain cancer risk has been of great interest for years. However, the effect of diabetic medications on cancer development is not fully understood. Prospective clinical trials have not elucidated the long-term influence of hypoglycemic drugs on cancer incidence and the safety for cancer-bearing patients with diabetes, whereas numerous preclinical studies have shown that antidiabetic drugs could have an impact on carcinogenesis processes beyond the glycemic control effect. Because there is no evidence of the safety profile of antidiabetic agents on cancer biology, careful consideration would be required when prescribing any medicines to patients with diabetes and existing tumor. In this review, we discuss the potential influence of each diabetes therapy in cancer 'initiation', 'promotion' and 'progression'.

Oral delivery of nanomedicine for genetic kidney disease

Chronic and genetic kidney diseases such as autosomal dominant polycystic kidney disease (ADPKD) have few therapeutic options, and clinical trials testing small molecule drugs have been unfavorable due to low kidney bioavailability and adverse side effects. Although nanoparticles can be designed to deliver drugs directly to the diseased site, there are no kidney-targeted nanomedicines clinically available, and most FDA-approved nanoparticles are administered intravenously which is not ideal for chronic diseases. To meet these challenges of chronic diseases, we developed a biomaterials-based strategy using chitosan particles (CP) for oral delivery of therapeutic, kidney-targeting peptide amphiphile micelles (KMs). We hypothesized that encapsuling KMs into CP would enhance the bioavailability of KMs upon oral administration given the high stability of chitosan in acidic conditions and mucoadhesive properties enabling absorption within the intestines. To test this, we evaluated the mechanism of KM access to the kidneys via intravital imaging and investigated the KM biodistribution in a porcine model. Next, we loaded KMs carrying the ADPKD drug metformin into CP (KM-CP-met) and measured in vitro therapeutic effect. Upon oral administration in vivo, KM-CP-met showed significantly greater bioavailability and accumulation in the kidneys as compared to KM only or free drug. As such, KM-CP-met treatment in ADPKD mice (Pkd1fl/fl;Pax8-rtTA;Tet-O-Cre which develops the disease over 120 days and mimics the slow development of ADPKD) showed enhanced therapeutic efficacy without affecting safety despite repeated treatment. Herein, we demonstrate the potential of KM-CP as a nanomedicine strategy for oral delivery for the long-term treatment of chronic kidney diseases.

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.

A case of exacerbated encephalopathy with stroke-like episodes and lactic acidosis triggered by metformin in a patient with MELAS

Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) is a maternally inherited multisystemic disorder caused by mutations in mitochondrial DNA that result in cellular energy deficiency. MELAS affects the most metabolically active organs, including the brain, skeletal muscles, cochlea, retina, heart, kidneys, and pancreas. As a result, about 85% of carriers of m.3243A > G, the most common mutation in MELAS, develop diabetes by the age of 70. Although metformin is the most widely prescribed drug for diabetes, its usefulness in mitochondrial dysfunction remains controversial. Here, we present the case of a 32-year-old Korean patient diagnosed with MELAS who presented with exacerbated stroke-like episodes and lactic acidosis triggered by metformin.

Rationale and Design of a Phase 2, Double-blind, Placebo-Controlled, Randomized Trial Evaluating AMP Kinase-Activation by Metformin in Focal Segmental Glomerulosclerosis

Introduction

Focal segmental glomerulosclerosis (FSGS), the most common primary glomerular disease leading to end-stage kidney disease (ESKD), is characterized by podocyte injury and depletion, whereas minimal change disease (MCD) has better outcomes despite podocyte injury. Identifying mechanisms capable of preventing podocytopenia during injury could transform FSGS to an "MCD-like" state. Preclinical data have reported conversion of an MCD-like injury to one with podocytopenia and FSGS by inhibition of AMP-kinase (AMPK) in podocytes. Conversely, in FSGS, AMPK-activation using metformin (MF) mitigated podocytopenia and azotemia. Observational studies also support beneficial effects of MF on proteinuria and chronic kidney disease (CKD) outcomes in diabetes. A randomized controlled trial (RCT) to test MF in podocyte injury with FSGS has not yet been conducted.

Methods

We report the rationale and design of phase 2, double-blind, placebo-controlled RCT evaluating the efficacy and safety of MF as adjunctive therapy in FSGS. By randomizing 30 patients with biopsy-confirmed FSGS to MF or placebo (along with standard immunosuppression), we will study mechanistic biomarkers that correlate with podocyte injury or depletion and evaluate outcomes after 6 months. We specifically integrate novel urine, blood, and tissue markers as surrogates for FSGS progression along with unbiased profiling strategies.

Results and Conclusion

Our phase 2 trial will provide insight into the potential efficacy and safety of MF as adjunctive therapy in FSGS-a crucial step to developing a larger phase 3 study. The mechanistic assays here will guide the design of other FSGS trials and contribute to understanding AMPK activation as a potential therapeutic target in FSGS. By repurposing an inexpensive agent, our results will have implications for FSGS treatment in resource-poor settings.

Metformin for sepsis-associated AKI: a protocol for the Randomized Clinical Trial of the Safety and FeasibiLity of Metformin as a Treatment for sepsis-associated AKI (LiMiT AKI)

INTRODUCTION

Acute kidney injury (AKI) is a common complication of sepsis associated with increased risk of death. Preclinical data and observational human studies suggest that activation of AMP-activated protein kinase, an ubiquitous master regulator of energy that can limit mitochondrial injury, with metformin may protect against sepsis-associated AKI (SA-AKI) and mortality. The Randomized Clinical Trial of the Safety and FeasibiLity of Metformin as a Treatment for sepsis-associated AKI (LiMiT AKI) aims to evaluate the safety and feasibility of enteral metformin in patients with sepsis at risk of developing SA-AKI.

METHODS AND ANALYSIS

Blind, randomised, placebo-controlled clinical trial in a single-centre, quaternary teaching hospital in the USA. We will enrol adult patients (18 years of age or older) within 48 hours of meeting Sepsis-3 criteria, admitted to intensive care unit, with oral or enteral access. Patients will be randomised 1:1:1 to low-dose metformin (500 mg two times per day), high-dose metformin (1000 mg two times per day) or placebo for 5 days. Primary safety outcome will be the proportion of metformin-associated serious adverse events. Feasibility assessment will be based on acceptability by patients and clinicians, and by enrolment rate.

ETHICS AND DISSEMINATION

This study has been approved by the Institutional Review Board. All patients or surrogates will provide written consent prior to enrolment and any study intervention. Metformin is a widely available, inexpensive medication with a long track record for safety, which if effective would be accessible and easy to deploy. We describe the study methods using the Standard Protocol Items for Randomized Trials framework and discuss key design features and methodological decisions. LiMiT AKI will investigate the feasibility and safety of metformin in critically ill patients with sepsis at risk of SA-AKI, in preparation for a future large-scale efficacy study. Main results will be published as soon as available after final analysis.

TRIAL REGISTRATION NUMBER

NCT05900284.

Metformin: From Diabetes to Cancer-Unveiling Molecular Mechanisms and Therapeutic Strategies

Metformin, a widely used anti-diabetic drug, has garnered attention for its potential in cancer management, particularly in breast and colorectal cancer. It is established that metformin reduces mitochondrial respiration, but its specific molecular targets within mitochondria vary. Proposed mechanisms include inhibiting mitochondrial respiratory chain Complex I and/or Complex IV, and mitochondrial glycerophosphate dehydrogenase, among others. These actions lead to cellular energy deficits, redox state changes, and several molecular changes that reduce hyperglycemia in type 2 diabetic patients. Clinical evidence supports metformin's role in cancer prevention in type 2 diabetes mellitus patients. Moreover, in these patients with breast and colorectal cancer, metformin consumption leads to an improvement in survival outcomes and prognosis. The synergistic effects of metformin with chemotherapy and immunotherapy highlights its potential as an adjunctive therapy for breast and colorectal cancer. However, nuanced findings underscore the need for further research and stratification by molecular subtype, particularly for breast cancer. This comprehensive review integrates metformin-related findings from epidemiological, clinical, and preclinical studies in breast and colorectal cancer. Here, we discuss current research addressed to define metformin's bioavailability and efficacy, exploring novel metformin-based compounds and drug delivery systems, including derivatives targeting mitochondria, combination therapies, and novel nanoformulations, showing enhanced anticancer effects.

Glycemia and Gluconeogenesis With Metformin and Liraglutide: A Randomized Trial in Youth-onset Type 2 Diabetes

OBJECTIVE

Elevated rates of gluconeogenesis are an early pathogenic feature of youth-onset type 2 diabetes (Y-T2D), but targeted first-line therapies are suboptimal, especially in African American (AA) youth. We evaluated glucose-lowering mechanisms of metformin and liraglutide by measuring rates of gluconeogenesis and β-cell function after therapy in AA Y-T2D.

METHODS

In this parallel randomized clinical trial, 22 youth with Y-T2D-age 15.3 ± 2.1 years (mean ± SD), 68% female, body mass index (BMI) 40.1 ± 7.9 kg/m2, duration of diagnosis 1.8 ± 1.3 years-were randomized to metformin alone (Met) or metformin + liraglutide (Lira) (Met + Lira) and evaluated before and after 12 weeks. Stable isotope tracers were used to measure gluconeogenesis [2H2O] and glucose production [6,6-2H2]glucose after an overnight fast and during a continuous meal. β-cell function (sigma) and whole-body insulin sensitivity (mSI) were assessed during a frequently sampled 2-hour oral glucose tolerance test.

RESULTS

At baseline, gluconeogenesis, glucose production, and fasting and 2-hour glucose were comparable in both groups, though Met + Lira had higher hemoglobin A1C. Met + Lira had a greater decrease from baseline in fasting glucose (-2.0 ± 1.3 vs -0.6 ± 0.9 mmol/L, P = .008) and a greater increase in sigma (0.72 ± 0.68 vs -0.05 ± 0.71, P = .03). The change in fractional gluconeogenesis was similar between groups (Met + Lira: -0.36 ± 9.4 vs Met: 0.04 ± 12.3%, P = .9), and there were no changes in prandial gluconeogenesis or mSI. Increased glucose clearance in both groups was related to sigma (r = 0.63, P = .003) but not gluconeogenesis or mSI.

CONCLUSION

Among Y-T2D, metformin with or without liraglutide improved glycemia but did not suppress high rates of gluconeogenesis. Novel therapies that will enhance β-cell function and target the elevated rates of gluconeogenesis in Y-T2D are needed.

View on Metformin: Antidiabetic and Pleiotropic Effects, Pharmacokinetics, Side Effects, and Sex-Related Differences

Metformin is a synthetic biguanide used as an antidiabetic drug in type 2 diabetes mellitus, achieved by studying the bioactive metabolites of Galega officinalis L. It is also used off-label for various other diseases, such as subclinical diabetes, obesity, polycystic ovary syndrome, etc. In addition, metformin is proposed as an add-on therapy for several conditions, including autoimmune diseases, neurodegenerative diseases, and cancer. Although metformin has been used for many decades, it is still the subject of many pharmacodynamic and pharmacokinetic studies in light of its extensive use. Metformin acts at the mitochondrial level by inhibiting the respiratory chain, thus increasing the AMP/ATP ratio and, subsequently, activating the AMP-activated protein kinase. However, several other mechanisms have been proposed, including binding to presenilin enhancer 2, increasing GLP1 release, and modification of microRNA expression. Regarding its pharmacokinetics, after oral administration, metformin is absorbed, distributed, and eliminated, mainly through the renal route, using transporters for cationic solutes, since it exists as an ionic molecule at physiological pH. In this review, particular consideration has been paid to literature data from the last 10 years, deepening the study of clinical trials inherent to new uses of metformin, the differences in effectiveness and safety observed between the sexes, and the unwanted side effects. For this last objective, metformin safety was also evaluated using both VigiBase and EudraVigilance, respectively, the WHO and European databases of the reported adverse drug reactions, to assess the extent of metformin side effects in real-life use.

Metformin: A Dual-Role Player in Cancer Treatment and Prevention

Cancer continues to pose a significant global health challenge, as evidenced by the increasing incidence rates and high mortality rates, despite the advancements made in chemotherapy. The emergence of chemoresistance further complicates the effectiveness of treatment. However, there is growing interest in the potential of metformin, a commonly prescribed drug for type 2 diabetes mellitus (T2DM), as an adjuvant chemotherapy agent in cancer treatment. Although the precise mechanism of action of metformin in cancer therapy is not fully understood, it has been found to have pleiotropic effects, including the modulation of metabolic pathways, reduction in inflammation, and the regulation of cellular proliferation. This comprehensive review examines the anticancer properties of metformin, drawing insights from various studies conducted in vitro and in vivo, as well as from clinical trials and observational research. This review discusses the mechanisms of action involving both insulin-dependent and independent pathways, shedding light on the potential of metformin as a therapeutic agent for different types of cancer. Despite promising findings, there are challenges that need to be addressed, such as conflicting outcomes in clinical trials, considerations regarding dosing, and the development of resistance. These challenges highlight the importance of further research to fully harness the therapeutic potential of metformin in cancer treatment. The aims of this review are to provide a contemporary understanding of the role of metformin in cancer therapy and identify areas for future exploration in the pursuit of effective anticancer strategies.

The Impact of Paediatric Obesity on Drug Pharmacokinetics: A Virtual Clinical Trials Case Study with Amlodipine

The incidence of paediatric obesity continues to rise worldwide and contributes to a range of diseases including cardiovascular disease. Obesity in children has been shown to impact upon the plasma concentrations of various compounds, including amlodipine. Nonetheless, information on the influence of obesity on amlodipine pharmacokinetics and the need for dose adjustment has not been studied previously. This study applied the physiologically based pharmacokinetic modelling and established a paediatric obesity population to assess the impact of obesity on amlodipine pharmacokinetics in children and explore the possible dose adjustments required to reach the same plasma concentration as non-obese paediatrics. The difference in predicted maximum concentration (Cmax) and area under the curve (AUC) were significant between children with and without obesity across the age group 2 to 18 years old when a fixed-dose regimen was used. On the contrary, a weight-based dose regimen showed no difference in Cmax between obese and non-obese from 2 to 9 years old. Thus, when a fixed-dose regimen is to be administered, a 1.25- to 1.5-fold increase in dose is required in obese children to achieve the same Cmax concentration as non-obese children, specifically for children aged 5 years and above.

Ianus Bifrons: The Two Faces of Metformin

The ancient Roman god Ianus was a mysterious divinity with two opposite faces, one looking at the past and the other looking to the future. Likewise, metformin is an "old" drug, with one side looking at the metabolic role and the other looking at the anti-proliferative mechanism; therefore, it represents a typical and ideal bridge between diabetes and cancer. Metformin (1,1-dimethylbiguanidine hydrochloride) is a drug that has long been in use for the treatment of type 2 diabetes mellitus, but recently evidence is growing about its potential use in other metabolic conditions and in proliferative-associated diseases. The aim of this paper is to retrace, from a historical perspective, the knowledge of this molecule, shedding light on the subcellular mechanisms of action involved in metabolism as well as cellular and tissue growth. The intra-tumoral pharmacodynamic effects of metformin and its possible role in the management of different neoplasms are evaluated and debated. The etymology of the name Ianus is probably from the Latin term ianua, which means door. How many new doors will this old drug be able to open?

Metformin and the Liver: Unlocking the Full Therapeutic Potential

Metformin is a highly effective medication for managing type 2 diabetes mellitus. Recent studies have shown that it has significant therapeutic benefits in various organ systems, particularly the liver. Although the effects of metformin on metabolic dysfunction-associated steatotic liver disease and metabolic dysfunction-associated steatohepatitis are still being debated, it has positive effects on cirrhosis and anti-tumoral properties, which can help prevent the development of hepatocellular carcinoma. Furthermore, it has been proven to improve insulin resistance and dyslipidaemia, commonly associated with liver diseases. While more studies are needed to fully determine the safety and effectiveness of metformin use in liver diseases, the results are highly promising. Indeed, metformin has a terrific potential for extending its full therapeutic properties beyond its traditional use in managing diabetes.

GC-MS analysis of 4-hydroxyproline: elevated proline hydroxylation in metformin-associated lactic acidosis and metformin-treated Becker muscular dystrophy patients

Metformin (N,N-dimethylbiguanide), an inhibitor of gluconeogenesis and insulin sensitizer, is widely used for the treatment of type 2 diabetes. In some patients with renal insufficiency, metformin can accumulate and cause lactic acidosis, known as metformin-associated lactic acidosis (MALA, defined as lactate ≥ 5 mM, pH < 7.35, and metformin concentration > 38.7 µM). Here, we report on the post-translational modification (PTM) of proline (Pro) to 4-hydroxyproline (OH-Pro) in metformin-associated lactic acidosis and in metformin-treated patients with Becker muscular dystrophy (BMD). Pro and OH-Pro were measured simultaneously by gas chromatography-mass spectrometry before, during, and after renal replacement therapy in a patient admitted to the intensive care unit (ICU) because of MALA. At admission to the ICU, plasma metformin concentration was 175 µM, with a corresponding lactate concentration of 20 mM and a blood pH of 7.1. Throughout ICU admission, the Pro concentration was lower compared to healthy controls. Renal excretion of OH-Pro was initially high and decreased over time. Moreover, during the first 12 h of ICU admission, OH-Pro seems to be renally secreted while thereafter, it was reabsorbed. Our results suggest that MALA is associated with hyper-hydroxyprolinuria due to elevated PTM of Pro to OH-Pro by prolyl-hydroxylase and/or inhibition of OH-Pro metabolism in the kidneys. In BMD patients, metformin, at the therapeutic dose of 3 × 500 mg per day for 6 weeks, increased the urinary excretion of OH-Pro suggesting elevation of Pro hydroxylation to OH-Pro. Our study suggests that metformin induces specifically the expression/activity of prolyl-hydroxylase in metformin intoxication and BMD.

Erythrocyte alterations in specimens of Danio rerio caused by exposure to metformin

The antidiabetic drug metformin is widely prescribed around the world. However, its permanence in different environmental concentrations has been associated with adverse toxicological effects in organisms that do not target its therapeutic action. In the aquatic environment, fish such as the Zebrafish (Danio rerio) have been considered potential bioindicators of environmental impacts and used as experimental models in toxicological studies due to the sensitivity of these species to different types of contaminants, including pharmaceuticals. Thus, this study aimed to analyze metformin's cytotoxic effects on Danio rerio erythrocytes. The animals were submitted to different concentrations of the drug (50 µg/L, 100 µg/L, 150 µg/L, and 10000 µg/L) for 365 days and subsequently observed employing light microscopy and scanning electron microscopy (SEM) to evaluate the alterations that occurred. Exposure of animals to metformin led to significant erythrocyte cell abnormalities across all tested concentrations, with a particularly pronounced effect at the higher concentration previously defined as the NOEC (No Observed Effect Concentration). Remarkable abnormalities included cytoplasmic vacuoles, echinocytes, and vesicle-like cytoplasmic fragments. These findings suggest that metformin, even at concentrations similar to those found in nature and at the NOEC level, exhibits cytotoxic potential in D. rerio, raising concerns about its potential health impacts.

The mechanisms of action of metformin on head and neck cancer in the pre-clinical setting: a scoping review

This scoping review identifies the mechanistic pathways of metformin when used to treat head and neck cancer cells, in the pre-clinical setting. Understanding the underlying mechanisms will inform future experimental designs exploring metformin as a potential adjuvant for head and neck cancer. This scoping review was conducted according to the Joanna-Briggs Institute framework. A structured search identified 1288 studies, of which 52 studies fulfilled the eligibility screen. The studies are presented in themes addressing hallmarks of cancer. Most of the studies demonstrated encouraging anti-proliferative effects in vitro and reduced tumor weight and volume in animal models. However, a few studies have cautioned the use of metformin which supported cancer cell growth under certain conditions.

A transcriptomics-based drug repositioning approach to identify drugs with similar activities for the treatment of muscle pathologies in spinal muscular atrophy (SMA) models

Spinal muscular atrophy (SMA) is a genetic neuromuscular disorder caused by the reduction of survival of motor neuron (SMN) protein levels. Although three SMN-augmentation therapies are clinically approved that significantly slow down disease progression, they are unfortunately not cures. Thus, complementary SMN-independent therapies that can target key SMA pathologies and that can support the clinically approved SMN-dependent drugs are the forefront of therapeutic development. We have previously demonstrated that prednisolone, a synthetic glucocorticoid (GC) improved muscle health and survival in severe Smn-/-;SMN2 and intermediate Smn2B/- SMA mice. However, long-term administration of prednisolone can promote myopathy. We thus wanted to identify genes and pathways targeted by prednisolone in skeletal muscle to discover clinically approved drugs that are predicted to emulate prednisolone's activities. Using an RNA-sequencing, bioinformatics, and drug repositioning pipeline on skeletal muscle from symptomatic prednisolone-treated and untreated Smn-/-; SMN2 SMA and Smn+/-; SMN2 healthy mice, we identified molecular targets linked to prednisolone's ameliorative effects and a list of 580 drug candidates with similar predicted activities. Two of these candidates, metformin and oxandrolone, were further investigated in SMA cellular and animal models, which highlighted that these compounds do not have the same ameliorative effects on SMA phenotypes as prednisolone; however, a number of other important drug targets remain. Overall, our work further supports the usefulness of prednisolone's potential as a second-generation therapy for SMA, identifies a list of potential SMA drug treatments and highlights improvements for future transcriptomic-based drug repositioning studies in SMA.

Examining the clinical relevance of metformin as an antioxidant intervention

In physiological concentrations, reactive oxygen species play a vital role in regulating cell signaling and gene expression. Nevertheless, oxidative stress is implicated in the pathogenesis of numerous diseases and can inflict damage on diverse cell types and tissues. Thus, understanding the factors that mitigate the deleterious effects of oxidative stress is imperative for identifying new therapeutic targets. In light of the absence of direct treatment recommendations for reducing oxidative stress, there is a continuing need for fundamental research that utilizes innovative therapeutic approaches. Metformin, known for its multifaceted beneficial properties, is acknowledged for its ability to counteract the adverse effects of increased oxidative stress at both molecular and cellular levels. In this review, we delve into recent insights regarding metformin's antioxidant attributes, aiming to expand its clinical applicability. Our review proposes that metformin holds promise as a potential adjunctive therapy for various diseases, given its modulation of oxidative stress characteristics and regulation of diverse metabolic pathways. These pathways include lipid metabolism, hormone synthesis, and immunological responses, all of which may experience dysregulation in disease states, contributing to increased oxidative stress. Furthermore, our review introduces potential novel metformin-based interventions that may merit consideration in future research. Nevertheless, the necessity for clinical trials involving this drug remains imperative, as they are essential for establishing therapeutic dosages and addressing challenges associated with dose-dependent effects.

Real-time monitoring of glucose metabolism and effects of metformin on HepG2 cells using 13C in-cell NMR spectroscopy

Metformin is currently a strong candidate antitumor agent for multiple cancers, and has the potential to inhibit cancer cell viability, growth, and proliferation. Metabolic reprogramming is a critical feature of cancer cells. However, the effects of metformin which targets glucose metabolism on HepG2 cancer cells remain unclear. In this study, to explore the effects of metformin on glucose metabolism in HepG2 cells, we conducted real-time metabolomic monitoring of live HepG2 cells treated with metformin using 13C in-cell NMR spectroscopy. Metabolic tracing with U-13C6-glucose revealed that metformin significantly increased the production of 13C-G3P and 13C-glycerol, which were reported to attenuate liver cancer development, but decreased the production of potential oncogenesis-supportive metabolites, including 13C-lactate, 13C-alanine, 13C-glycine, and 13C-glutamate. Moreover, the expression levels of enzymes associated with the measured metabolites were carried out. The results showed that the levels of ALT1, MCT4, GPD2 and MPC1 were greatly reduced, which were consistent with the changes of measured metabolites in 13C in-cell NMR spectroscopy. Overall, our approach directly provides fundamental insights into the effects of metformin on glucose metabolism in live HepG2 cells, and highlights the potential mechanism of metformin, including the increase in production of G3P and glycerol derived from glucose, as well as the inhibition of glucose incorporation into lactate, alanine, glutamate, and glycine.

Protective effects of metformin in the pro-inflammatory cytokine induced intestinal organoids injury model

Pathogenesis of inflammatory bowel disease (IBD) accompanies disrupted intestinal tight junctions. However, many approaches of therapeutics for IBD are focused only on anti-inflammatory effects and most cellular experiments are based on two-dimensional cell lines which have insufficient circumstances of intestine. Thus, here, we used three-dimensional structure intestinal organoids to investigate effects of metformin in the in vitro IBD condition. In this study, we focused on both tight junctions and the levels of inflammatory cytokines. Metformin enhances the intestinal barrier in injured intestine via upregulation of AMP-activated protein kinase, dysfunction of which contributes to the pathogenesis of intestinal diseases. We aim to investigate the effects of metformin on cytokine-induced injured intestinal organoids. Tumor necrosis factor-alpha (TNF-α) was used to induce intestinal injury in an organoid model, and the effects of metformin were assessed. Cell viability and levels of inflammatory cytokines were quantified in addition to tight junction markers. Furthermore, 4 kDa FITC-dextran was used to assess intestinal permeability. The upregulation of inflammatory cytokine levels was alleviated by metformin, which also restored the intestinal epithelium permeability in TNF-α-treated injury organoids. We confirmed that claudin-2 and claudin-7, representative tight junction markers, were also protected by metformin treatment. This study confirms the protective effects of metformin, which could be used as a therapeutic strategy for inflammatory intestinal diseases.

Metformin-Cimetidine Drug Interaction and Risk of Lactic Acidosis in Renal Failure: A Pharmacovigilance-Pharmacokinetic Appraisal

OBJECTIVE

This study aimed to evaluate lactic acidosis (LA) risk when using metformin combined with histamine H2 receptor inhibitors (H2RI) in patients with renal failure (RF).

RESEARCH DESIGN AND METHODS

This study analyzed FDA Adverse Event Reporting System data (2012Q4 to 2022Q4) to characterize reports of LA associated with metformin alone or combined with H2RI. Using a disproportionality approach, LA risk signal in the overall population and in patients with RF was assessed. A physiologically based pharmacokinetic (PBPK) model was developed to predict metformin and cimetidine pharmacokinetic changes following conventional doses of the combinations in patients with various degrees of RF. To explore its correlation with LA risk, a peak plasma metformin concentration of 3 mg/L was considered the threshold.

RESULTS

Following the 2016 U.S. Food and Drug Administration metformin approval for mild-to-moderate RF, the percentage of patients with RF reporting LA associated with metformin combined with H2RI increased. Disproportionality analysis showed reported LA risk signal associated with metformin and cimetidine in the overall population within the study timeframe only. Furthermore, with PBPK simulations, for metformin (1,000 mg b.i.d.) with cimetidine (300 mg q.i.d. or 400 mg b.i.d.) in stage 1 of chronic kidney disease, metformin (1,000 mg b.i.d.) with cimetidine (300 mg q.i.d. or 400 mg b.i.d. or 800 mg q.d.) in stage 2, and most combinations in stage 3, the peak plasma metformin concentrations exceeded the 3 mg/L threshold.

CONCLUSIONS

Metformin combined with cimetidine at conventional doses may cause LA in patients with mild-to-moderate RF.

Effect of Metformin on Plasma and Cerebrospinal Fluid Biomarkers in Non-Diabetic Older Adults with Mild Cognitive Impairment Related to Alzheimer's Disease

Background

Alzheimer's disease (AD) is a complicated condition involving multiple metabolic and immunologic pathophysiological processes that can occur with the hallmark pathologies of amyloid-β, tau, and neurodegeneration. Metformin, an anti-diabetes drug, targets several of these disease processes in in vitro and animal studies. However, the effects of metformin on human cerebrospinal fluid (CSF) and plasma proteins as potential biomarkers of treatment remain unexplored.

Objective

Using proteomics data from a metformin clinical trial, identify the impact of metformin on plasma and CSF proteins.

Methods

We analyzed plasma and CSF proteomics data collected previously (ClinicalTrials.gov identifier: NCT01965756, conducted between 2013 and 2015), and conduced bioinformatics analyses to compare the plasma and CSF protein levels after 8 weeks of metformin or placebo use to their baseline levels in 20 non-diabetic patients with mild cognitive impairment (MCI) and positive AD biomarkers participants.

Results

50 proteins were significantly (unadjusted p < 0.05) altered in plasma and 26 in CSF after 8 weeks of metformin use, with 7 proteins in common (AZU1, CASP-3, CCL11, CCL20, IL32, PRTN3, and REG1A). The correlation between changes in plasma and CSF levels of these 7 proteins after metformin use relative to baseline levels was high (r = 0.98). The proteins also demonstrated temporal stability.

Conclusions

Our pilot study is the first to investigate the effect of metformin on plasma and CSF proteins in non-diabetic patients with MCI and positive AD biomarkers and identifies several candidate plasma biomarkers for future clinical trials after confirmatory studies.

Mass Spectrometry Study about In Vitro and In Vivo Reaction between Metformin and Glucose: A Preliminary Investigation on Alternative Biological Behavior

Metformin is the most prescribed glucose-lowering drug worldwide; globally, over 100 million patients are prescribed this drug annually. Some different action mechanisms have been proposed for this drug, but, surprisingly, no metabolite of metformin has ever been described. It was considered interesting to investigate the possible reaction of metformin with glucose following the Maillard reaction pattern. The reaction was first performed in in vitro conditions, showing the formation of two adducts that originated by the condensation of the two molecular species with the losses of one or two water molecules. Their structures were investigated by liquid chromatography coupled with mass spectrometry (HPLC-MS), tandem mass spectrometry (MS/MS) and accurate mass measurements (HRMS). The species originated via the reaction of glucose and metformin and were called metformose and dehydrometformose, and some structural hypotheses were conducted. It is worth to emphasize that they were detected in urine samples from a diabetic patient treated with metformin and consequently they must be considered metabolites of the drug, which has never been identified before now. The glucose-related substructure of these compounds could reflect an improved transfer across cell membranes and, consequently, new hypotheses could be made about the biological targets of metformin.

Box Behnken optimization of cubosomes for enhancing the anticancer activity of metformin: Design, characterization, and in-vitro cell proliferation assay on MDA-MB-231 breast and LOVO colon cancer cell lines

This study aimed to formulate and statistically optimize cubosomal formulations of metformin (MTF) to enhance its breast anticancer activity. A Box Behnken design was employed using Design-Expert® software. The formulation variables were glyceryl monooleate concentration (GMO) w/w%, Pluronic F-127 concentration (PF127) w/w% and Tween 80 concentration w/w% whereas Entrapment efficiency (EE%), Vesicles' size (VS) and Zeta potential (ZP) were set as the dependent responses. The design expert software was used to perform the process of optimization numerically. X ray diffraction (XRD), Transmission electron microscope (TEM), in-vitro release study, short-term stability study, and in in-vitro cell proliferation assay on the MDA-MB-231 breast cancer and LOVO cancer cell lines were used to validate the optimized cubosomal formulation. The optimized formulation had a composition of 4.35616 (w/w%) GMO, 5 (w/w%) PF127 and 7.444E-6 (w/w%) Tween 80 with a desirability of 0.733. The predicted values for EE%, VS and ZP were 78.0592%, 307.273 nm and - 26.8275 mV, respectively. The validation process carried out on the optimized formula revealed that there were less than a 5% variance from the predicted responses. The XRD thermograms showed that MTF was encapsulated inside the cubosomal vesicles. TEM images of the optimized MTF cubosomal formulation showed spherical non-aggregated nanovesicles. Moreover, it revealed a sustained release profile of MTF in comparison to the MTF solution. Stability studies indicated that optimum cubosomal formulation was stable for thirty days. Cytotoxicity of the optimized cubosomal formulation was enhanced on the MDA-MB-231 breast and LOVO cancer cell lines compared to MTF solution even at lower concentrations. However, it showed superior cytotoxic effect on breast cancer cell line. So, cubosomes could be considered a promising carrier of MTF to treat breast and colon cancers.