The phantom of lactic acidosis due to metformin in patients with diabetes

Optimizing metformin therapy in practice: Tailoring therapy in specific patient groups to improve tolerability, efficacy and outcomes

Metformin is the first-line medication for type 2 diabetes. It is effective and safe, provided some caution is taken in specific populations. In patients with chronic kidney disease, metformin may provide long-term benefits, and it is a first-line therapy for diabetes, but the estimated glomerular filtration rate (eGFR) must be assessed regularly, to minimize the risk for metformin accumulation. When eGFR is 30-60 mL/min/1.73m2, the dose should be reconsidered, and sick-days education provided. Metformin should be discontinued when eGFR falls below 30 mL/min/1.73m2. Metformin accumulation may increase the risk for lactic acidosis if concomitant risk factors for hyperlactataemia (liver or respiratory insufficiency, sepsis, acute heart failure) are present; in these conditions, metformin is contraindicated, even although the available evidence is reassuring. Patients on metformin often complain of gastrointestinal side effects (mainly diarrhoea and nausea) during therapy initiation, but they may sometimes occur after years of stable therapy. These usually resolve if the dose is carefully titrated, or by switching to the extended-release formulation. Patients with obesity may benefit from the significant, although modest, metformin-associated weight loss and appetite reduction. During pregnancy, metformin is associated with a reduction of pregnancy complications, especially in obese women, but some concern remains, because metformin crosses the placenta, and it is associated with a significantly lower mean birth weight than insulin. In the elderly, gastrointestinal tolerability and renal function must be reassessed more often. Vitamin B-12 should be screened regularly in long-time metformin users because metformin may induce clinical vitamin B-12 deficiency.

Euglycemic Ketoacidosis and Lactic Acidosis Associated With Metformin Toxicity

In patients with diabetes, diabetic ketoacidosis (DKA) is a well-documented potential complication, usually presenting with hyperglycemia, anion gap acidosis, and positive ketones. Metformin toxicity in the setting of acute renal failure is also a well-known cause of lactic acidosis. However, metformin-induced euglycemic ketoacidosis is less well-known or studied. We report a case of metformin toxicity in the setting of acute renal failure with both lactic acidosis and ketosis and an initial confounded clinical presentation of sulphonylurea-induced hypoglycemia. A high index of suspicion for metformin-associated lactic acidosis (MALA) and metformin-associated lactic acidosis with euglycemic ketoacidosis (MALKA) should be in place in patients who are taking metformin and presenting with acute renal failure and euglycemia.

Metformin treatment is associated with improved survival in diabetic patients hospitalized with acute heart failure: A prospective observational study using the Korean acute heart failure registry data

AIMS

Although the hypothesis that metformin is beneficial for patients with diabetes and heart failure (HF) has been steadily raised, there is limited data on metformin use in patients with acute HF. We analyzed the association of metformin on all-cause mortality in hospitalized patients with type 2 diabetes and acute HF.

METHODS

The Korean Acute Heart Failure registry prospectively enrolled patients hospitalized for acute HF from 2011 to 2014. Among this cohort, we analyzed patients with diabetes with baseline estimated glomerular filtration rate (eGFR) of 30 ml/min/1.73 m2 or more. We analyzed the all-cause mortality and re-hospitalization for HF within 1 year after discharge. Inverse probability treatment weighting method was used to adjust baseline differences on metformin treatment.

RESULTS

The study analyzed data from 1,309 patients with HF and diabetes (mean age 69 years, 56 % male). Among them, 613 (47 %) patients were on metformin at admission. During the median follow-up period of 11 months, 132 (19 %) and 74 (12 %) patients not receiving and receiving metformin treatment died, respectively. The mortality rate was lower in metformin users than in non-users (hazard ratio 0.616 [0.464-0.819] P<0.001). After adjustment, metformin was significantly associated with a lower risk for the mortality (hazard ratio 0.677 [0.495-0.928] P=0.015). In subgroup analyses, this association remains significant irrespective of baseline kidney function (eGFR <60 or ≥60 ml/min/1.73 m2, P-for-interaction=0.176) or left ventricular ejection fraction (<40 %, 40-49 %, or ≥50 %, P-for-interaction=0.224).

CONCLUSIONS

Metformin treatment at the time of admission was associated with a lower risk for 1-year mortality in patients with diabetes, hospitalized for acute HF.

Appraisal of guidelines for managing contrast medium in patients with metformin: consensuses, controversies, and gaps

OBJECTIVES

The current guidelines contain substantial inconsistency regarding the use of metformin concomitantly with contrast media. The objective of this study is to appraise the guidelines and summarize the agreements and differences among recommendations.

METHODS

Our search focused on English language guidelines published between 2018 and 2021. Guidelines for the management of contrast media in patients with continuous metformin were included. Guidelines were assessed using the Appraisal of Guidelines for Research and Evaluation II instrument.

RESULTS

Six guidelines out of 1134 fulfilled the inclusion criteria with an AGREE II score of 79.2% (IQR 72.7 to 85.1%). There was good overall quality of the guidelines, with six considered "strongly recommended." CPGs scored poorly in "Clarity of Presentation" and "Applicability," with scores of 75.9% and 76.4%, respectively. The intraclass correlation coefficients were excellent in each domain. There are some guidelines (33.3%) that recommend discontinuation of metformin in patients with an eGFR of < 30 mL/min/1.73 m2, while some guidelines (16.7%) suggest the threshold of renal function should be eGFR < 40 mL/min/1.73 m2.

CONCLUSIONS

Most guidelines recommend withdrawing metformin before using contrast agents in diabetic patients with severely impaired kidney function but disagree on the renal function thresholds. Furthermore, the gaps regarding discontinuing metformin with moderate renal impairment (30 mL/min/1.73 m2 < eGFR < 60 mL/min/1.73 m2) must be considered in future studies.

KEY POINTS

• Guidelines involving metformin and contrast agents are reliable and optimal. • Most guidelines advocate discontinuing metformin before using contrast agents in diabetic patients with advanced renal failure, but there are controversial suggestions regarding kidney function thresholds. • The gaps regarding the time of discontinuation of the metformin with moderate renal impairment (30 mL/min/1.73 m2 < eGFR < 60 mL/min/1.73 m2) must be considered in the extensive RCT studies.

Setd2 inactivation sensitizes lung adenocarcinoma to inhibitors of oxidative respiration and mTORC1 signaling

SETD2 is a tumor suppressor that is frequently inactivated in several cancer types. The mechanisms through which SETD2 inactivation promotes cancer are unclear, and whether targetable vulnerabilities exist in these tumors is unknown. Here we identify heightened mTORC1-associated gene expression programs and functionally higher levels of oxidative metabolism and protein synthesis as prominent consequences of Setd2 inactivation in KRAS-driven mouse models of lung adenocarcinoma. Blocking oxidative respiration and mTORC1 signaling abrogates the high rates of tumor cell proliferation and tumor growth specifically in SETD2-deficient tumors. Our data nominate SETD2 deficiency as a functional marker of sensitivity to clinically actionable therapeutics targeting oxidative respiration and mTORC1 signaling.

Metformin: new applications for an old drug

Metformin is a biguanide, evolved as one of the most widely used medicines. The applications of this component include but are not limited to reducing blood glucose, weight loss, and polycystic ovary syndrome. Studies about other probable indications have emerged, indicating that this agent can also be utilized for other purposes. In this review, applications of metformin are noticed based on the current evidence. Metformin commonly is used as an off-label drug in non-alcoholic fatty liver disease (NAFLD), but it worsens inflammation and should not be used for this purpose, according to the latest research. Metformin decreased the risk of death in patients with liver cirrhosis. It is an effective agent in the prevention and improvement of survival in patients suffering hepatocellular carcinoma. There is evidence of the beneficial effects of metformin in colorectal cancer, early-stage prostate cancer, breast cancer, urothelial cancer, blood cancer, melanoma, and bone cancer, suggesting metformin as a potent anti-tumor agent. Metformin shows neuroprotective effects and provides a potential therapeutic benefit for mild cognitive impairment and Alzheimer's disease (AD). It also has been shown to improve mental function and reduce the incidence of dementia. Another condition that metformin has been shown to slow the progression of is Duchenne muscular dystrophy. Regarding infectious diseases, tuberculosis (TB) and coronavirus disease (COVID-19) are among the conditions suggested to be affected by metformin. The beneficial effects of metformin in cardiovascular diseases were also reported in the literature. Concerning renal function, studies showed that daily oral administration of metformin could ameliorate kidney fibrosis and normalize kidney structure and function. This study reviewed the clinical and preclinical evidence about the possible benefits of metformin based on recent studies. Numerous questions like whether these probable indications of metformin can be observed in non-diabetics, need to be described by future basic experiments and clinical studies.

Lactic Acidosis Related to Pharmacotherapy and Human Diseases

Lactic acidosis represents one of the most common conditions that can compromise the health of intensive care unit (ICU) patients, increasing the mortality of patients with high levels of Lactate who do not receive a proper treatment within the first 6 h of hospitalization. There are two enantiomers of lactic acid: L-lactic acid (when the concentration increases, it can lead to a state of severe acidemia risking cardiovascular collapse, causing an increase in mortality in ICU patients) and D lactic acid (produced in the human organism by microbiota and its production increases during some pathological status). Generally, increased levels of serum lactic acid could be due to numerous factors, including hypoxia (caused for example by septic/cardiogenic/hypovolemic or obstructive shock), specific pathologies (e.g., liver disease), use of some drugs (e.g., metformin), presence of toxins, and trauma. Since the underlying cause could be fatal for the ICU patient, it is important to understand the root of this clinical status with a view to correct it and prevent the risk of a poor clinical outcome. Prevention and early treatment are the keys to control the negative clinical consequences. The aim of this review is to revise the scientific literature for further confirmation about the importance of early identification of acidotic statuses and to underline how an early diagnosis can prevent the worst clinical outcome, especially for ICU patients who are more fragile compared to the general population.

Quality and Characteristics of 4241 Case Reports of Lactic Acidosis in Metformin Users Reported to a Large Pharmacovigilance Database

Objective

Metformin-associated lactic acidosis (MaLA) occurs rarely and is thus difficult to study. We analysed 4241 individual case safety reports of lactic acidosis (LA) that implicated metformin as a suspected drug reported to the pharmacovigilance database of Merck KGaA, Darmstadt, Germany. The primary objective was to review reports for quality and completeness of data to support diagnoses of MaLA. We also explored the correlations between reported biomarkers, and associations between biomarkers and outcomes.

Research Design and Methods

Records were analysed for completeness in supporting diagnoses of LA or metformin-associated LA (MaLA), against commonly used diagnostic criteria. Correlations between indices of exposure to metformin and biomarkers of LA and mortality were investigated.

Results

Missing data was common, especially for plasma metformin. Clinical/biomarker evidence supported a diagnosis of LA in only 33% of cases (LA subpopulation) and of MaLA in only 9% (MaLA subpopulation). The metformin plasma level correlated weakly with plasma lactate (positive) and pH (negative). About one-fifth (21.9%) of cases reported a fatal outcome. Metformin exposure (plasma level or dose) was not associated with increased mortality risk (there was a suggestion of decreased risk at higher levels of exposure to metformin). Plasma lactate was the only variable associated with increased risk of mortality. Examination of concomitant risk factors for MaLA identified renal dysfunction (including of iatrogenic origin) as a potential driver of mortality in this population.

Conclusion

Despite the high frequency of missing data, this is the largest analysis of cases of MaLA supported by measurements of circulating metformin, and lactate, and pH, to date. Plasma lactate, and not metformin dose or plasma level, appeared to be the main driver of mortality in the setting of LA or MaLA. Further research with more complete case reports is required.

Cardiac Dysfunction Due to Thiamine Deficiency after Hemodialysis for Biguanide-related Lactic Acidosis

Biguanide is an ideal drug for the treatment of type 2 diabetes mellitus. When used appropriately, the incidence of lactic acidosis is reported to be very low. Risk factors associated with biguanide-related lactic acidosis include chronic kidney disease, congestive heart failure, alcohol use, severe dehydration, shock, hypoxic states, sepsis, and advanced age. We herein report a case of cardiac dysfunction due to thiamine deficiency after hemodialysis in a patient with suspected biguanide-related lactic acidosis. Patients who develop severe lactic acidosis while taking biguanides should be given a large dose of thiamine without delay, given the possibility of thiamine deficiency as a complication.

Continuous use of metformin in patients receiving contrast medium: what is the evidence? A systematic review and meta-analysis

OBJECTIVES

Substantial inconsistencies exist in current guidelines regarding recommendations of metformin usage with the administration of a contrast medium. We aimed to perform a meta-analysis to determine whether the risks of contrast-induced acute kidney injury (CI-AKI) and lactic acidosis increase with metformin use in diabetic patients receiving a contrast medium.

METHODS

Studies were retrieved from databases from inception to May 15, 2021. Studies that compared the outcomes of using metformin with not using metformin during contrast medium administration were included. The primary outcomes were incidence of CI-AKI and lactic acidosis. The secondary outcomes were renal function changes from baseline. Data analysis was using risk ratio (RR) for dichotomous outcomes and mean differences (MD) with 95% confidence intervals (CI) for continuous outcomes.

RESULTS

Analyses of two randomized controlled trials and four retrospective cohorts examining a total of 1459 patients revealed no significant differences in the incidence of CI-AKI (RR = 1.08; 95% CI, 0.72 to 1.63) and in changes in renal function measurements (serum creatinine: MD = 0.00 mg/dL, 95% CI, - 0.05 to 0.05; estimated glomerular filtration rate: MD = 0.22, 95% CI, - 2.47 to 2.91) after contrast medium administration between patients using and not using metformin.

CONCLUSIONS

There is no evidence that continuing metformin during contrast medium administration is associated with a higher risk of CI-AKI, lactic acidosis, or renal function deterioration compared to patients who discontinued metformin or who were not metformin users. The limited quality of the included studies may compromise the strength of evidence provided in this meta-analysis.

KEY POINTS

There is no need to discontinue metformin either before or after intravenous contrast medium exposure in patients with eGFR > 30 mL/min/1.73 m2. In patients receiving intra-arterial contrast medium with first-pass renal exposure, there is no need to withhold metformin if eGFR is above 60 mL/min/1.73 m2. For patients who have an eGFR level between 30 and 60 mL/min/1.73 m2 and are receiving intra-arterial contrast medium with first-pass renal exposure, no case of lactic acidosis was observed based on present data, but further evidence is needed to make a strong suggestion regarding its safety.

Effects of Metformin in Heart Failure: From Pathophysiological Rationale to Clinical Evidence

Type 2 diabetes mellitus (T2DM) is a worldwide major health burden and heart failure (HF) is the most common cardiovascular (CV) complication in affected patients. Therefore, identifying the best pharmacological approach for glycemic control, which is also useful to prevent and ameliorate the prognosis of HF, represents a crucial issue. Currently, the choice is between the new drugs sodium/glucose co-transporter 2 inhibitors that have consistently shown in large CV outcome trials (CVOTs) to reduce the risk of HF-related outcomes in T2DM, and metformin, an old medicament that might end up relegated to the background while exerting interesting protective effects on multiple organs among which include heart failure. When compared with other antihyperglycemic medications, metformin has been demonstrated to be safe and to lower morbidity and mortality for HF, even if these results are difficult to interpret as they emerged mainly from observational studies. Meta-analyses of randomized controlled clinical trials have not produced positive results on the risk or clinical course of HF and sadly, large CV outcome trials are lacking. The point of force of metformin with respect to new diabetic drugs is the amount of data from experimental investigations that, for more than twenty years, still continues to provide mechanistic explanations of the several favorable actions in heart failure such as, the improvement of the myocardial energy metabolic status by modulation of glucose and lipid metabolism, the attenuation of oxidative stress and inflammation, and the inhibition of myocardial cell apoptosis, leading to reduced cardiac remodeling and preserved left ventricular function. In the hope that specific large-scale trials will be carried out to definitively establish the metformin benefit in terms of HF failure outcomes, we reviewed the literature in this field, summarizing the available evidence from experimental and clinical studies reporting on effects in heart metabolism, function, and structure, and the prominent pathophysiological mechanisms involved.

Glucose-lowering therapy in patients undergoing percutaneous coronary intervention

The number of individuals with diabetes and pre-diabetes is constantly increasing. These conditions are overrepresented in patients undergoing percutaneous coronary intervention and are associated with adverse prognosis. Optimal glycaemic control during an acute coronary syndrome is a relevant factor for the improvement of longer-term outcomes. In addition, the implementation of newer glucose-lowering drugs with proven cardiovascular benefits has a remarkable impact on recurrence of events, hospitalisations for heart failure and mortality. In this narrative review, we outline the current state-of-the art recommendations for glucose-lowering therapy in patients with diabetes undergoing coronary intervention. In addition, we discuss the most recent evidence-based indications for revascularisation in patients with diabetes as well as the targets for glycaemic control post revascularisation. Current treatment goals for concomitant risk factor control are also addressed. Lastly, we acknowledge the presence of knowledge gaps in need of future research.

Management of Cardiometabolic Complications in Patients With Nonalcoholic Fatty Liver Disease: A Review of the Literature With Recommendations

Nonalcoholic fatty liver disease (NAFLD) comprises a spectrum of liver conditions characterized by significant lipid deposition within hepatocytes. As an overarching diagnosis, NAFLD contains a continuum of progressive liver diseases ranging from isolated liver steatosis to necroinflammatory states leading to end-stage liver disease. Nonalcoholic fatty liver and nonalcoholic steatohepatitis are distinguished by their histologic patterns, with the former exhibiting steatosis without fibrosis or inflammation. This important distinction provides clinicians a timeline within the NAFLD staging to target appropriate interventions against modifiable risk factors. NAFLD is likely formed in response to metabolic imbalances that damage the livers adaptive capacity. Metabolic conditions leading to steatosis mirror common cardiovascular risk factors, including dyslipidemia, diabetes mellitus, and obesity. Acknowledging the common risk factors for development and progression of NAFLD, it is unsurprising the first-line management focuses on the treatment of metabolic syndrome with an emphasis on weight reduction in obese populations. The purpose of this review is to provide a detailed summary of the literature as well as outline the current treatment recommendations for patients with NAFLD with a detailed focus on pharmacologic antiobesity interventions.

Effects of Metformin Exposure on Survival in a Large National Cohort of Patients With Diabetes and Cirrhosis

BACKGROUND & AIMS

Type II diabetes mellitus worsens the prognosis of cirrhosis. Multiple medications including metformin and statins often are co-administered to manage patients with diabetes. The aim of this study was to assess the impact of metformin exposure on mortality, hepatic decompensation, and hepatocellular carcinoma in individuals with diabetes and cirrhosis, controlling for multiple concomitant exposures.

METHODS

We performed a retrospective cohort study of patients with cirrhosis diagnosed between January 1, 2008, through June 30, 2016, in the Veterans Health administration. Marginal structural models and propensity-matching approaches were implemented to quantify the treatment effect of metformin in patients with pre-existing diabetes with or without prior metformin exposure.

RESULTS

Among 74,984 patients with cirrhosis, diabetes mellitus was present before the diagnosis of cirrhosis in 53.8%, and was diagnosed during follow-up evaluation in 4.8%. Before the diagnosis of cirrhosis, 11,114 patients had active utilization of metformin. In these patients, metformin, statin, and angiotensinogen-converting enzyme inhibitor/angiotensin-2-receptor blocker exposure were associated independently with reduced mortality (metformin hazard ratio, 0.68; 95% CI, 0.61-0.75); metformin was not associated with reduced hepatocellular carcinoma or hepatic decompensation after adjustment for concomitant statin exposure. For patients with diabetes before a diagnosis of cirrhosis but no prior metformin exposure, metformin similarly was associated with reduced mortality (hazard ratio, 0.72; 95% CI, 0.35-0.97), but not with reduced hepatocellular carcinoma or hepatic decompensation.

CONCLUSIONS

Metformin use in patients with cirrhosis and diabetes appears safe and is associated independently with reduced overall, but not liver-related, mortality, hepatocellular carcinoma, or decompensation after adjusting for concomitant statin and angiotensinogen-converting enzyme inhibitor/angiotensin-2-receptor blocker exposure.

Spontaneously Reported Adverse Drug Reactions and Their Description in Hospital Discharge Reports: A Retrospective Study

The inclusion of spontaneously reported adverse drug reactions (ADRs) in hospital discharge reports was examined, in addition to the factors associated with their inclusion, the resulting therapeutic decisions, and any recommendations made upon patient discharge regarding the suspected offending drugs. ADRs that were spontaneously reported during 2017 and 2018 to the pharmacovigilance program were retrospectively analyzed. Information regarding patient characteristics, drug treatments, and ADRs was collected from the ADR notifications and from patient electronic medical records. The dependent variable was the mentioning of ADRs in the discharge reports, while characteristics of the ADRs, pharmacovigilance causality algorithms, and some of the suspected drugs themselves were the independent variables during bivariant analysis. A total of 286 reports of suspected ADRs from 271 patients (50.2% female; 77% adults) were included. Information regarding the ADRs was present in the discharge reports for 238 reports (83.2%); the ADR seriousness and the lack of potential alternative causes were the only associated factors. Withdrawal or withdrawal and substitution by an alternative drug were the most common therapeutic decisions, although often no recommendation was made. Overall, there is still room for improvement in terms of including information related to ADRs in hospital discharge reports.

New Aspects of Diabetes Research and Therapeutic Development

Both type 1 and type 2 diabetes mellitus are advancing at exponential rates, placing significant burdens on health care networks worldwide. Although traditional pharmacologic therapies such as insulin and oral antidiabetic stalwarts like metformin and the sulfonylureas continue to be used, newer drugs are now on the market targeting novel blood glucose-lowering pathways. Furthermore, exciting new developments in the understanding of beta cell and islet biology are driving the potential for treatments targeting incretin action, islet transplantation with new methods for immunologic protection, and the generation of functional beta cells from stem cells. Here we discuss the mechanistic details underlying past, present, and future diabetes therapies and evaluate their potential to treat and possibly reverse type 1 and 2 diabetes in humans. SIGNIFICANCE STATEMENT: Diabetes mellitus has reached epidemic proportions in the developed and developing world alike. As the last several years have seen many new developments in the field, a new and up to date review of these advances and their careful evaluation will help both clinical and research diabetologists to better understand where the field is currently heading.

The Genetics of Adverse Drug Outcomes in Type 2 Diabetes: A Systematic Review

Background: Adverse drug reactions (ADR) are a major clinical problem accounting for significant hospital admission rates, morbidity, mortality, and health care costs. One-third of people with diabetes experience at least one ADR. However, there is notable interindividual heterogeneity resulting in patient harm and unnecessary medical costs. Genomics is at the forefront of research to understand interindividual variability, and there are many genotype-drug response associations in diabetes with inconsistent findings. Here, we conducted a systematic review to comprehensively examine and synthesize the effect of genetic polymorphisms on the incidence of ADRs of oral glucose-lowering drugs in people with type 2 diabetes.

Methods: A literature search was made to identify articles that included specific results of research on genetic polymorphism and adverse effects associated with oral glucose-lowering drugs. The electronic search was carried out on 3rd October 2020, through Cochrane Library, PubMed, and Web of Science using keywords and MeSH terms.

Result: Eighteen articles consisting of 10, 383 subjects were included in this review. Carriers of reduced-function alleles of organic cation transporter 1 (OCT 1, encoded by SLC22A1) or reduced expression alleles of plasma membrane monoamine transporter (PMAT, encoded by SLC29A4) or serotonin transporter (SERT, encoded by SLC6A4) were associated with increased incidence of metformin-related gastrointestinal (GI) adverse effects. These effects were shown to exacerbate by concomitant treatment with gut transporter inhibiting drugs. The CYP2C9 alleles, ^*2 (rs1799853C>T) and ^*3 (rs1057910A>C) that are predictive of low enzyme activity were more common in subjects who experienced hypoglycemia after treatment with sulfonylureas. However, there was no significant association between sulfonylurea-related hypoglycemia and genetic variants in the ATP-binding cassette transporter sub-family C member 8 (ABCC8)/Potassium Inwardly Rectifying Channel Subfamily J Member 11 (KCNJ11). Compared to the wild type, the low enzyme activity C allele at CYP2C8^*3 (rs1057910A>C) was associated with less weight gain whereas the C allele at rs6123045 in the NFATC2 gene was significantly associated with edema from rosiglitazone treatment.

Conclusion: In spite of limited studies investigating genetics and ADR in diabetes, some convincing results are emerging. Genetic variants in genes encoding drug transporters and metabolizing enzymes are implicated in metformin-related GI adverse effects, and sulfonylurea-induced hypoglycemia, respectively. Further studies to investigate newer antidiabetic drugs such as DPP-4i, GLP-1RA, and SGLT2i are warranted. In addition, pharmacogenetic studies that account for race and ethnic differences are required.

Validated spectrofluorometric determination of hypoglycemic combination, in pure form and pharmaceutical formulation using 9,10-phenanthraquinone reagent

The aim of this work is to develop and validate a simple, rapid, highly sensitive and selective spectrofluorometric method for determination of Metformin HCl (MFH) and Glibenclamide (GLB) in their binary mixture without prior separation. The proposed method based on measuring the native fluorescence intensity of GLB at λ_emission = 348 nm, after excitation at λ_excitation = 226 nm and measuring the fluorescence intensity of the fluorescent product produced from the derivatization of MFH using 9,10-phenanthraquinone in alkaline media at λ_emission = 416 nm after excitation at λ_excitation = 240 nm. The proposed spectrofluorometric method allowed sensitive determination of the studied drugs with a limit of quantitation of 0.04 and 0.01 μg mL^-1 for MFH and GLB, respectively, providing greater sensitivity than the reported one. Validation of the proposed method was carried out according to ICH guidelines with respect to linearity, accuracy, precision, and selectivity. The developed method was successfully applied for the determination of MFH and GLB in laboratory prepared mixtures and pharmaceutical formulation and the results obtained were statistically compared to those of the reported HPLC method with no significant difference between them.

Metformin dosage patterns in type 2 diabetes patients in a real-world setting in the United States

AIM

To examine metformin dosage patterns among adults with type 2 diabetes in an integrated healthcare system in the US.

METHODS

Using electronic medical records, the proportions of patients receiving different initial metformin doses were reported. Proportion of patients receiving ≥1500 mg metformin daily at initiation or within six months after initiation and the associated sociodemographic and clincal factors were examined.

RESULTS

The cohort included 715 patients (52.6% female, 64.1% white, and mean age = 57.0 ± 12.7 years). Of these, 31.3% received an initial daily metformin dose of <850 mg, 46.9% received 850-1499 mg, and 21.8% received ≥1500 mg and 244 (34.1%) patients received ≥1500 mg metformin daily at initiation or within six months after initiation. Patients aged 65-79 years (vs. those aged <50 years) and blacks (vs. whites) were less likely and Hispanics (vs. whites) and patients with higher HbA1c before metformin initiation were more likely to receive ≥1500 mg metformin daily at initiation or within six months after initiation.

CONCLUSIONS

Study findings suggest a need for efforts to maximize the proportion of eligible patients receiving a recommended metformin dose. Factors impacting metformin dosage identified in the study could be a useful guidance.

Biowaiver Monographs for Immediate Release Solid Oral Dosage Forms: Metformin Hydrochloride

Data are examined regarding possible waiver of in vivo bioequivalence testing (i.e. biowaiver) for approval of metformin hydrochloride (metformin) immediate-release solid oral dosage forms. Data include metformin's Biopharmaceutics Classification System (BCS) properties, including potential excipient interactions. Metformin is a prototypical transporter-mediated drug and is highly soluble, but only 50% of an orally administered dose is absorbed from the gut. Therefore, metformin is a BCS Class III substance. A BCS-based approval approach for major changes to marketed products and new generics is admissible if test and reference dosage forms have the identical active pharmaceutical ingredient and if in vitro dissolution from both are very rapid (i.e. at least 85% within 15 min at pH 1.2, 4.5, and 6.8). Recent International Council for Harmonisation BCS guidance indicates all excipients for Class III biowaivers are recommended to be qualitatively the same and quantitatively similar (except for preservatives, flavor agents, colorant, or capsule shell or film coating excipients). However, despite metformin being a prototypical transporter-mediated drug, there is no evidence that commonly used excipients impact metformin absorption, such that this restriction on excipients for BCS III drugs merits regulatory relief. Commonly used excipients in usual amounts are not likely to impact metformin absorption.

Lactic Acidosis in Diabetic Ketoacidosis: A Marker of Severity or Alternate Substrate for Metabolism

PURPOSE

The lactate level is being increasingly used as a marker of severity of illness and prognosis in multitude of critical conditions. However, its role in diabetic ketoacidosis (DKA) is not well defined.

AIM

To determine the prevalence and clinical importance along with the underlying role of metformin in lactic acidosis (LA) in patients admitted with DKA.

METHODS

A 2-year prospective and observational study involving 62 consenting in hospital DKA patients. Plasma lactate level on arrival, its clinical significance and relationship with morbidity and mortality in patients with DKA was evaluated.

RESULTS

The prevalence of LA (lactate ≥2.5 mmol/l) among the study cohort was found to be 55% with significant LA (≥5 mmol/l) documented in 16%. The median lactate level was 2.55 mmol/l (interquartile range, 1.70-3.20). No significant difference in the severity of LA was seen with metformin use. Lactate correlated positively with initial plasma glucose (IPG) (P = 0.001) and APACHE-II Score (P = 0.002); correlated negatively with systolic blood pressure (P = 0.003), pH (P = 0.002) and severity of DKA (P = 0.001). After controlling for AKI, APACHE II score and blood pressure, lactate continued to correlate positively with IPG (P = 0.002). No mortality or significant morbidity was documented in the entire cohort.

CONCLUSIONS

LA has a significant presence in patients with DKA; however, it is not associated with mortality or significant morbidity. Moreover, there was no significant difference in severity of LA with metformin use. Elevated lactate levels may be an adaptation to provide alternate substrate for metabolism in the presence of hypoinsulinemic state. The study results provide rationale for large well-designed studies evaluating in-depth clinical relationship of lactate in DKA.

Prevalence, severity, and nature of risk factors associated with drug-drug interactions in geriatric patients receiving cancer chemotherapy: A prospective study in a tertiary care teaching hospital

INTRODUCTION

Polypharmacy increases hazard of drug-drug interactions(DDIs), hospitalization, treatment toxicity, and mortality in elderly individuals with cancer. The present study explores and analyzes prevalence and severity of DDIs in geriatric cancer patients subjected to anticancer chemotherapy, their mechanisms, stratification of severity, and correlation between DDI risk and number of medications taken.

METHODS

This was a cross-sectional study conducted between January-July 2019 at the Medical Oncology/Hematology and Radiation-Oncology Departments, All India Institute of Medical Sciences(AIIMS) Rishikesh. The study included a convenience sampling of 126 geriatric cancer patients.

RESULTS

126 patients were enrolled in present study. DDIs were identified in 97.6% of elderly cancer patients, and 88.9% had at least one DDI with antineoplastic medications. Highest number of DDIs involving antineoplastic medications in any given patient was 12. DDIs involving medications used for treatment of non-cancerous diseases were observed in 83.3% of patients; highest number of interactions identified in any given patient was 15. Out of 473 interactions, 237(50.1%) DDIs were attributable to pharmacodynamic mechanisms of action. 126(27%) of DDIs involved pharmacokinetic mechanisms and 110(23.6%) involved unknown mechanisms. In this present study, total number of DDIs could be positively correlated with total number of medications and number of health problems.

CONCLUSIONS

Geriatric cancer patients are at high risk of DDIs ascribable to polypharmacy. Physicians may utilize online DDI checking softwares to alert themselves, characterize potential DDIs, and modify medications judiciously. An integrative and algorithmic approach with inclusion of geriatricians, oncologists, cardiologists, general practitioners, and clinical pharmacologists/ pharmacists is imperative to optimize drug therapy.

Metformin delays neurological symptom onset in a mouse model of neuronal complex I deficiency

Complex I (also known as NADH-ubiquinone oxidoreductase) deficiency is the most frequent mitochondrial disorder present in childhood. NADH-ubiquinone oxidoreductase iron-sulfur protein 3 (NDUFS3) is a catalytic subunit of the mitochondrial complex I; NDUFS3 is conserved from bacteria and essential for complex I function. Mutations affecting complex I, including in the Ndufs3 gene, cause fatal neurodegenerative diseases, such as Leigh syndrome. No treatment is available for these conditions. We developed and performed a detailed molecular characterization of a neuron-specific Ndufs3 conditional KO mouse model. We showed that deletion of Ndufs3 in forebrain neurons reduced complex I activity, altered brain energy metabolism, and increased locomotor activity with impaired motor coordination, balance, and stereotyped behavior. Metabolomics analyses showed an increase of glycolysis intermediates, suggesting an adaptive response to the complex I defect. Administration of metformin to these mice delayed the onset of the neurological symptoms but not of neuronal loss. This improvement was likely related to enhancement of glucose uptake and utilization, which are known effects of metformin in the brain. Despite reports that metformin inhibits complex I activity, our findings did not show worsening a complex I defect nor increases in lactic acid, suggesting that metformin should be further evaluated for use in patients with mitochondrial encephalopathies.

Metformin delays onset of mitochondrial encephalopathy in a CNS model of mitochondrial oxidative phosphorylation defect.

Metformin Biodistribution: A Key to Mechanisms of Action?

Metformin has undisputed glucose-lowering effects in diabetes and an impressive safety record. It has also shown promising effects beyond diabetes, and several hundred clinical trials involving metformin are currently planned or active. Metformin targets intracellular effectors, but exactly which remain to be established, and in an era of precision medicine, an incomplete understanding of mechanisms of action may limit the use of metformin. Distribution of metformin depends on specific organic cation transporter proteins that are organ- and species-specific. Therefore, target tissues of metformin can be identified by cellular uptake of the drug, and exploring the biodistribution of the drug in humans becomes an attractive strategy to assist the many investigations into the mechanisms of action of metformin performed in animals. In this review, we combine the emerging evidence from the use of 11C-labeled metformin in humans to discuss metformin action in liver, intestines, and kidney, which are the organs with the most avid uptake of the drug.

Repurposing Antidiabetic Drugs for Cardiovascular Disease

Metabolic diseases and diabetes represent an increasing global challenge for human health care. As associated with a strongly elevated risk of developing atherosclerosis, kidney failure and death from myocardial infarction or stroke, the treatment of diabetes requires a more effective approach than lowering blood glucose levels. This review summarizes the evidence for the cardioprotective benefits induced by antidiabetic agents, including sodium-glucose cotransporter 2 inhibitor (SGLT2i) and glucagon-like peptide-1 receptor agonist (GLP1-RA), along with sometimes conversely discussed effects of dipeptidyl peptidase-4 inhibitor (DPP4i) and metformin in patients with high cardiovascular risk with or without type 2 diabetes. Moreover, the proposed mechanisms of the different drugs are described based on the results of preclinical studies. Recent cardiovascular outcome trials unexpectedly confirmed a beneficial effect of GLP-1RA and SGLT2i in type 2 diabetes patients with high cardiovascular risk and with standard care, which was independent of glycaemic control. These results triggered a plethora of studies to clarify the underlying mechanisms and the relevance of these effects. Taken together, the available data strongly highlight the potential of repurposing the original antidiabetics GLP1-RA and SGLT2i to improve cardiovascular outcome even in non-diabetic patients with cardiovascular diseases.

The Association between Metformin Therapy and Lactic Acidosis

INTRODUCTION AND OBJECTIVES

There is increasing evidence to suggest that therapeutic doses of metformin are unlikely to cause lactic acidosis. The aims of this research were (1) to formally evaluate the association between metformin therapy and lactic acidosis in published case reports using two causality scoring systems, (2) to determine the frequency of pre-existing independent risk factors in published metformin-associated lactic acidosis cases, (3) to investigate the association between risk factors and mortality in metformin-associated lactic acidosis cases, and (4) to explore the relationship between prescribed metformin doses, elevated metformin plasma concentrations and the development of lactic acidosis in cases with chronic renal impairment.

METHODS

A systematic review was conducted to identify metformin-associated lactic acidosis cases. Causality was assessed using the World Health Organisation-Uppsala Monitoring Centre system and the Naranjo adverse drug reaction probability scale. Compliance to dosing guidelines was investigated for cases with chronic renal impairment as well as the association between steady-state plasma metformin concentrations prior to admission.

RESULTS

We identified 559 metformin-associated lactic acidosis cases. Almost all cases reviewed (97%) presented with independent risk factors for lactic acidosis. The prescribed metformin dose exceeded published guidelines in 60% of cases in patients with impaired kidney function. Metformin steady-state plasma concentrations prior to admission were predicted to be below the proposed upper limit of the therapeutic range of 5 mg/L.

CONCLUSIONS

Almost all cases of metformin-associated lactic acidosis reviewed presented with independent risk factors for lactic acidosis, supporting the suggestion that metformin plays a contributory role. The prescribed metformin dose, on average, exceeded the dosing recommendations by 1000 mg/day in patients with varying degrees of renal impairment but the predicted pre-admission plasma concentrations did not exceed the therapeutic range.

The Phantom of Metformin-Induced Lactic Acidosis in End-Stage Renal Disease Patients: Time to Reconsider with Peritoneal Dialysis Treatment

Objective

Metformin continues to be the safest and most widely used antidiabetic drug. In spite of its well-known benefits; metformin use in end-stage renal disease (ESRD) patients is still restricted. Little has been reported about the effect of peritoneal dialysis (PD) on metformin clearance and the phantom of lactic acidosis deprives ESRD patients from metformin therapeutic advantages. Peritoneal dialysis is probably a safeguard against lactic acidosis, and it is likely that using this drug would be feasible in this group of patients.

Material and methods

The study was conducted on 83 PD patients with type 2 diabetes mellitus. All patients were on automated PD (APD). Metformin was administered in a dose of 500 - 1,000 mg daily. Patients were monitored for glycemic control. Plasma lactic acid and plasma metformin levels were monitored on a scheduled basis. Peritoneal fluid metformin levels were measured. In addition, the relation between plasma metformin and plasma lactate was studied.

Results

Mean fasting blood sugar (FBS) was 10.9 ± 0.5 and 7.8 ± 0.7, and mean hemoglobin A1-C (HgA1C) was 8.2 ± 0.8 and 6.4 ± 1.1 at the beginning and end of the study, respectively (p < 0.001). The mean body mass index (BMI) was 29.1 ± 4.1 and 27.3 ± 4.5 at the beginning and at the end of the study, respectively (p < 0.001). The overall mean plasma lactate level across all blood samples was 1.44 ± 0.6. Plasma levels between 2 and 3 mmol/L were found in 11.8% and levels of 3 - 3.6 mmol/L in 2.4% plasma samples. Hyperlactemia (level > 2 and < 5 mmol/L) was not associated with overt acidemia. None of our patients had lactic acidosis (levels > 5 mmol/L). Age ≥ 60 was a predictor for hyperlactemia. No relationship was found between plasma metformin and lactate levels.

Conclusion

Metformin may be used with caution in a particular group of ESRD patients who are on APD. Metformin allows better diabetic control with significant reduction of BMI. Information on the relationship between metformin and plasma lactate levels is lacking. Peritoneal dialysis appears to be a safeguard against the development of lactic acidosis in this group of patients.

Updated guidelines for intravenous contrast use for CT and MRI

Intravenous (IV) contrast material is used extensively for CT and MRI scans done in emergency departments (ED). Its use is essential to make many critical diagnoses in ED patients. While adverse reactions can occur, newer research has added to our knowledge of IV contrast media tolerance and safety leading to improved and more liberal guidelines for intravenous contrast use. The updated information described in this review article indicates how intravenous contrast can be used safely in more patients, more expeditiously and with fewer precautions than with prior guidelines. This review article explains the basis for the new recommendations for intravenous contrast material use and describes indicated precautions and preparations to avoid adverse reactions for iodinated agents used for CT and gadolinium agents for MRI.

Drug-nutrient interactions: discovering prescription drug inhibitors of the thiamine transporter ThTR-2 (SLC19A3)

BACKGROUND

Transporter-mediated drug-nutrient interactions have the potential to cause serious adverse events. However, unlike drug-drug interactions, these drug-nutrient interactions receive little attention during drug development. The clinical importance of drug-nutrient interactions was highlighted when a phase III clinical trial was terminated due to severe adverse events resulting from potent inhibition of thiamine transporter 2 (ThTR-2; SLC19A3).

OBJECTIVE

In this study, we tested the hypothesis that therapeutic drugs inhibit the intestinal thiamine transporter ThTR-2, which may lead to thiamine deficiency.

METHODS

For this exploration, we took a multifaceted approach, starting with a high-throughput in vitro primary screen to identify inhibitors, building in silico models to characterize inhibitors, and leveraging real-world data from electronic health records to begin to understand the clinical relevance of these inhibitors.

RESULTS

Our high-throughput screen of 1360 compounds, including many clinically used drugs, identified 146 potential inhibitors at 200 μM. Inhibition kinetics were determined for 28 drugs with half-maximal inhibitory concentration (IC50) values ranging from 1.03 μM to >1 mM. Several oral drugs, including metformin, were predicted to have intestinal concentrations that may result in ThTR-2-mediated drug-nutrient interactions. Complementary analysis using electronic health records suggested that thiamine laboratory values are reduced in individuals receiving prescription drugs found to significantly inhibit ThTR-2, particularly in vulnerable populations (e.g., individuals with alcoholism).

CONCLUSIONS

Our comprehensive analysis of prescription drugs suggests that several marketed drugs inhibit ThTR-2, which may contribute to thiamine deficiency, especially in at-risk populations.

Metformin: The Answer to Cancer in a Flower? Current Knowledge and Future Prospects of Metformin as an Anti-Cancer Agent in Breast Cancer

Interest has grown in studying the possible use of well-known anti-diabetic drugs as anti-cancer agents individually or in combination with, frequently used, chemotherapeutic agents and/or radiation, owing to the fact that diabetes heightens the risk, incidence, and rapid progression of cancers, including breast cancer, in an individual. In this regard, metformin (1, 1-dimethylbiguanide), well known as 'Glucophage' among diabetics, was reported to be cancer preventive while also being a potent anti-proliferative and anti-cancer agent. While meta-analysis studies reported a lower risk and incidence of breast cancer among diabetic individuals on a metformin treatment regimen, several in vitro, pre-clinical, and clinical studies reported the efficacy of using metformin individually as an anti-cancer/anti-tumor agent or in combination with chemotherapeutic drugs or radiation in the treatment of different forms of breast cancer. However, unanswered questions remain with regards to areas such as cancer treatment specific therapeutic dosing of metformin, specificity to cancer cells at high concentrations, resistance to metformin therapy, efficacy of combinatory therapeutic approaches, post-therapeutic relapse of the disease, and efficacy in cancer prevention in non-diabetic individuals. In the current article, we discuss the biology of metformin and its molecular mechanism of action, the existing cellular, pre-clinical, and clinical studies that have tested the anti-tumor potential of metformin as a potential anti-cancer/anti-tumor agent in breast cancer therapy, and outline the future prospects and directions for a better understanding and re-purposing of metformin as an anti-cancer drug in the treatment of breast cancer.

BÜCHI nano spray dryer B-90: a promising technology for the production of metformin hydrochloride-loaded alginate-gelatin nanoparticles

The current study aimed to formulate gelatin/sodium alginate nanoparticles utilizing BÜCHI nano spray dryer B-90. Nanoparticles possess many of the advantages including new routes of drug administrations and sustained release properties. Utilizing B-90 technology, metformin hydrochloride (MET) nanoparticles were successfully developed. Preformulation studies such as atomization head mesh size, flow rate, head temperature, polymer viscosity, and surface tension, were adjusted. Additionally, post-formulation characters such as particle size, flowability, surface scan, and dissolution profiles, were evaluated. Spray head (7 µm hole), flow rate (3.5 ml/min) and head temperature (120 °C) were optimized. Polymer viscosity was less than 11.2 cP with a surface tension less than 70.1 dyne/cm. Moreover, anti-diabetic effects of MET formulations were evaluated in streptozotocin-induced diabetic rats. Here, discrete, non-aggregated free-flowing nanoparticle powders with a particle size less than 850 nm were generated. Gelatin/sodium-alginate (1:3) produced nanoparticles were successfully sustained by the in vitro release profile of the drug. In vivo evaluations of the previous formula showed a significant reduction of blood glucose level over 24 h. In conclusion, Nano Spray Dryer B-90 (Büchi Labortechnik AG, Flawil, Switzerland) offers a promising technology for nanoparticles formulation as controlled drug delivery systems enhancing compliance of type-II diabetic patients.

Metformin inhibits IL-6 signaling by decreasing IL-6R expression on multiple myeloma cells

IL-6 signaling plays a crucial role in the pathogenesis of a number of diseases, including multiple myeloma, primary amyloidosis, cytokine release syndrome and other inflammatory conditions. It is central for the growth and survival of malignant plasma cells. IL-6R and IL-6ST receptors transduce IL-6 signaling. Molecular mechanisms regulating expression of IL-6R are not well understood and current therapies are based on monoclonal antibody to target IL-6 signaling. Small molecule inhibitors targeting IL-6 signaling are highly desirable. Metformin specifically decreased IL-6R expression which is mediated via AMPK, mTOR, and miR34a. This is a novel finding and adds to existing therapies targeting IL-6 signaling.

The impact of oral anti-diabetic medications on heart failure: lessons learned from preclinical studies

The prevalence of heart failure (HF) in the diabetic population has rapidly increased over the past 2 decades, triggering research about the impact of oral anti-diabetic medications on it. Unfortunately, not all success at the bench in preclinical experiments has translated to success at the bedside. On the other hand, recent promising clinical data from oral SGLT2 inhibitors mainly lack mechanistic explanation from experimental studies. Hence, it is critical to understand the lessons learned from prior translational studies to gain a better knowledge of the mechanisms of oral anti-diabetic drugs in HF. This review aims to summarize the results from preclinical studies regarding the interaction between oral anti-diabetic medications and heart failure development and/or exacerbation. Although there is a wide spectrum of controversial results, the underlying hope is that the clinical success rate will improve and the adverse events during ineffective targeted therapy will be limited.

Cystatin C measurement leads to lower metformin dosage in elderly type 2 diabetic patients

The aim of this study was to provide evidence for the hypothesis that estimated glomerular filtration rate from serum Cystatin C (eGFRcys) is better to be determined for all elderly type 2 diabetes mellitus (T2DM) patients based on eGFRcys upward and downward reclassification rate for hypothetical metformin dose reduction by eGFRcys at the GFR decision point of 45 mL/min/1.73 m². A total of 265 consecutive T2DM elderly patients (age range 65‐91 years) from outpatient diabetic clinic were included in the study. The Kidney Disease Improving Global Outcomes (KDIGO) guidelines for metformin dosing were strictly followed. Estimated glomerular filtration rate from serum creatinine (eGFRcrea) led to results of metformin eligibility. Each of the results of eGFRcrea‐based eligibility was further compared to eGFRcys‐based eligibility. Creatinine was measured by enzymatic method standardized against international reference material SRM 967. Cystatin C was determined by method traceable to DA ERM 471 international standard. eGFRcrea and eGFRcys were calculated according to Chronic Kidney Disease Epidemiology Collaboration (CKD‐EPI) equations. A downward reclassification rate was higher than upward reclassification rate (31 vs 3, respectively; P < 0.0001). The median (IQR) eGFRcrea was higher than eGFRcys (73 (58‐85) vs 63 (50‐75) mL/min/1.73 m², respectively; P < 0.0001). eGFRcys reclassified significant proportion of patients with T2DM from metformin eligible CKD stages to less or non‐eligible stages. The downward reclassification was more frequent in patients older than 80 years (P < 0.01). Cystatin C‐based eGFR selects more complicated patients, where lower doses of metformin are possibly advisable. We recommend calculating both eGFRcrea and eGFRcys for metformin dosing in elderly patients with T2DM.

Review of Biguanide (Metformin) Toxicity

In the 1920s, guanidine, the active component of Galega officinalis, was shown to lower glucose levels and used to synthesize several antidiabetic compounds. Metformin (1,1 dimethylbiguanide) is the most well-known and currently the only marketed biguanide in the United States, United Kingdom, Canada, and Australia for the treatment of non-insulin-dependent diabetes mellitus. Although phenformin was removed from the US market in the 1970s, it is still available around the world and can be found in unregulated herbal supplements. Adverse events associated with therapeutic use of biguanides include gastrointestinal upset, vitamin B₁₂ deficiency, and hemolytic anemia. Although the incidence is low, metformin toxicity can lead to hyperlactatemia and metabolic acidosis. Since metformin is predominantly eliminated from the body by the kidneys, toxicity can occur when metformin accumulates due to poor clearance from renal insufficiency or in the overdose setting. The dominant source of metabolic acidosis associated with hyperlactatemia in metformin toxicity is the rapid cytosolic adenosine triphosphate (ATP) turnover when complex I is inhibited and oxidative phosphorylation cannot adequately recycle the vast quantity of H+ from ATP hydrolysis. Although metabolic acidosis and hyperlactatemia are markers of metformin toxicity, the degree of hyperlactatemia and severity of acidemia have not been shown to be of prognostic value. Regardless of the etiology of toxicity, treatment should include supportive care and consideration for adjunct therapies such as gastrointestinal decontamination, glucose and insulin, alkalinization, extracorporeal techniques to reduce metformin body burden, and metabolic rescue.

Cardioprotection by Metformin: Beneficial Effects Beyond Glucose Reduction

Metformin is a biguanide that is widely used as an insulin-sparing agent to treat diabetes. When compared with the general population, diabetics are twice as likely to die from fatal myocardial infarction and congestive heart failure (CHF). There has been a significant concern regarding the use of metformin in patients with CHF because of their higher tendency to develop lactic acidosis. However, large epidemiological trials have reported better cardiovascular prognosis with metformin compared to other glucose-lowering agents among diabetics. Additionally, metformin has reduced the risk of reinfarction and all-cause mortality in patients with coronary artery disease and CHF, respectively. The protection against cardiovascular diseases appears to be independent of the anti-hyperglycemic effects of metformin. These effects are mediated through an increase in 5' adenosine monophosphate-activated protein kinase (AMPK) phosphorylation and by increased phosphorylation of endothelial nitric oxide synthase (eNOS) in cardiomyocytes with an increased production of nitric oxide (NO). Metformin preconditions the heart against ischemia-reperfusion injury and may improve myocardial remodeling after an ischemic insult. The preponderance of evidence currently suggests that metformin is safe in patients with CHF, prompting the Food and Drug Administration to remove CHF as a contraindication from the package insert of all generic metformin preparations. In this narrative, along with a limited meta-analysis of available studies, we have reviewed the pleiotropic (non-glucose-lowering) effects of metformin that potentially contribute to its cardioprotective properties. Additionally, we have reviewed issues surrounding the safety of metformin in patients with cardiac diseases.

Ethical and Practical Considerations in Removing Black Box Warnings from Drug Labels

Boxed warnings-also known as "black box" warnings-can be a powerful tool in communicating drug risks to physicians and patients. The overall number of boxed warnings has grown in recent years as the US Food and Drug Administration (FDA) has approved more drugs on the basis of limited pre-marketing information and as new safety issues for marketed drugs have been identified. Two recent manufacturers' petitions to remove boxed warnings on the drugs rosiglitazone (Avandia) and varenicline (Chantix) have led to divergent FDA decisions and revealed different considerations involved in boxed warning imposition and removal. For ethical and practical reasons, the FDA is justified in applying a higher standard for boxed warning removal than for imposition, as removal of a boxed warning may have unintended effects on physician and patient behavior. However, no guidelines on boxed warning removal currently exist. To promote safe use of approved prescription drugs, the FDA should adopt a uniform and transparent process governing decisions to impose or remove boxed warnings.

Metformin and ageing: improving ageing outcomes beyond glycaemic control

In a world where the population is ageing, there is growing interest and demand for research evaluating strategies that address the ageing process. After 60 years of successful use of metformin in our pharmaceutical armamentarium, we are learning that, beyond improving glycaemic control, metformin may have additional mechanisms and pathways of action that need further study. Although, metformin's effect on clinical ageing outcomes may still be considered speculative, the findings from studies into cellular and animal models and from observational and pilot human studies support the existence of beneficial effects on ageing. At present, progress for human research, using randomised clinical trials to evaluate metformin's clinical impact, has just started. Here, we present a review on the ageing process and the mechanisms involved, and the role that metformin may have to counter these. We go on to discuss the upcoming large randomised clinical trials that may provide insight on the use of metformin for ageing outcomes beyond glycaemic control.

Metformin Use in Practice: Compliance With Guidelines for Patients With Diabetes and Preserved Renal Function

IN BRIEF Several contraindications limit the use of metformin, most notably the risk of lactic acidosis. This article reports on an examination of a population of patients with diabetes with preserved renal function to evaluate provider compliance with guidelines on metformin use and to identify factors that contributed when practice diverged from recommendations. It found that metformin was withheld from approximately one-third of these patients because of 1) an existent contraindication to metformin, 2) patient behavior or preference, or 3) provider preference or bias based on patient or personal factors. Although providers generally follow current recommendations for the use of metformin, deviations from guidelines in practice are common.

Effect of prescribing metformin according to eGFR instead of serum creatinine level: A study based on Korean National Health and Nutrition Examination Survey (KNHANES) 2009-2014

BACKGROUND

The metformin label has recently been changed from serum creatinine (sCr)-based to estimated glomerular filtration rate (eGFR)-based indication, which is expected to expand its use for patients with mild renal insufficiency. However, because the sCr level is lower in Asians than in Caucasians at the same level of renal function, this change might not expand metformin use in the Asian population. We investigated the effect of this change among Korean patients with diabetes.

METHODS

Data from the Korean National Health and Nutrition Examination Survey 2009 to 2014 were used and included 4,127 adult patients with diabetes. The metformin eligibility was assessed by the sCr level (1.4 mg/dL for women and 1.5 mg/dL for men) or by eGFR categories (contraindicated, <30; indeterminate, ≥30, <45; likely safe, ≥45 mL/min/1.73 m2) calculated by various eGFR equations including MDRD equation. We designated the 'expanding' and 'contracting' population as those who are likely safe according to eGFR among sCr-ineligible patients and those contraindicated according to eGFR among sCr-eligible patients, respectively. Results were weighted to the whole Korean adult population.

RESULTS

All eGFR equations showed expansion in the population for whom metformin is likely safe, ranging from 14.3% to 19.9% of the sCr-ineligible population. With the MDRD equation, the expanding population was 15,264 (15.8%) and the contracting population was 0 (0.0%). Male sex and younger age were significantly associated with the expanding population.

CONCLUSIONS

Contrary to our concern, prescribing metformin according to eGFR substantially expanded the indication of its use among the Korean diabetic patients.

Clinical Outcomes of Metformin Use in Populations With Chronic Kidney Disease, Congestive Heart Failure, or Chronic Liver Disease: A Systematic Review

BACKGROUND

Recent changes to the U.S. Food and Drug Administration boxed warning for metformin will increase its use in persons with historical contraindications or precautions. Prescribers must understand the clinical outcomes of metformin use in these populations.

PURPOSE

To synthesize data addressing outcomes of metformin use in populations with type 2 diabetes and moderate to severe chronic kidney disease (CKD), congestive heart failure (CHF), or chronic liver disease (CLD) with hepatic impairment.

DATA SOURCES

MEDLINE (via PubMed) from January 1994 to September 2016, and Cochrane Library, EMBASE, and International Pharmaceutical Abstracts from January 1994 to November 2015.

STUDY SELECTION

English-language studies that: 1) examined adults with type 2 diabetes and CKD (with estimated glomerular filtration rate less than 60 mL/min/1.73 m2), CHF, or CLD with hepatic impairment; 2) compared diabetes regimens that included metformin with those that did not; and 3) reported all-cause mortality, major adverse cardiovascular events, and other outcomes of interest.

DATA EXTRACTION

2 reviewers abstracted data and independently rated study quality and strength of evidence.

DATA SYNTHESIS

On the basis of quantitative and qualitative syntheses involving 17 observational studies, metformin use is associated with reduced all-cause mortality in patients with CKD, CHF, or CLD with hepatic impairment, and with fewer heart failure readmissions in patients with CKD or CHF.

LIMITATIONS

Strength of evidence was low, and data on multiple outcomes of interest were sparse. Available studies were observational and varied in follow-up duration.

CONCLUSION

Metformin use in patients with moderate CKD, CHF, or CLD with hepatic impairment is associated with improvements in key clinical outcomes. Our findings support the recent changes in metformin labeling.

PRIMARY FUNDING SOURCE

U.S. Department of Veterans Affairs. (PROSPERO: CRD42016027708).

Provider Decisions and Patient Outcomes After Premature Metformin Discontinuation

The purpose of this study was to evaluate the effects of alternative antihyperglycemic therapy after discontinuation of metformin due to documented declining renal function. This retrospective, single-site study evaluated patients who had metformin discontinued between 1 January 1999 and 30 September 2013. Medical records were evaluated for documented adverse events, subsequent glycemic control, and costs associated with the alternative therapy. Patients served as their own controls. A total of 179 patients met study entry criteria, and their peak A1C was significantly higher within the year after metformin discontinuation (P <0.001). After the provider added new medications to control patients' blood glucose, their A1C by the end of the first year after discontinuing metformin was similar to their A1C while taking metformin. Significant weight gain accompanied the use of the medications added to replace metformin, with an average increase of 3.81 kg (P <0.001). Additionally, after discontinuing metformin, more patients experienced hypoglycemia with the addition of other medications to control their blood glucose (P <0.001). As expected, the cost of therapy was significantly higher (P <0.0001) after metformin was discontinued because metformin was generically available, whereas the replacement medications frequently were not. Providers should consider the expanded recommendations for the use of metformin in patients with mild to moderate stable renal dysfunction to help such patients avoid weight gain, hypoglycemia, loss of blood glucose control, and increased costs.

Gene expression signature: a powerful approach for drug discovery in diabetes

Type 2 diabetes (T2D) is increasing in prevalence at an alarming rate around the world. Much effort has gone into the discovery and design of antidiabetic drugs; however, those already available are unable to combat the underlying causes of the disease and instead only moderate the symptoms. The reason for this is that T2D is a complex disease, and attempts to target one biological pathway are insufficient to combat the full extent of the disease. Additionally, the underlying pathophysiology of this disease is yet to be fully elucidated making it difficult to design drugs that target the mechanisms involved. Therefore, the approach of designing new drugs aimed at a specific molecular target is not optimal and a more expansive, unbiased approach is required. In this review, we will look at the current state of diabetes treatments and how these target the disease symptoms but are unable to combat the underlying causes. We will also review how the technique of gene expression signatures (GESs) has been used successfully for other complex diseases and how this may be applied as a powerful tool for the discovery of new drugs for T2D.

The Dramatic Recovery of a Patient with Biguanide-associated Severe Lactic Acidosis Following Thiamine Supplementation

Biguanides are a drug of choice for the treatment of type 2 diabetes mellitus. Although they can cause lactic acidosis in susceptible patients with predisposing risk factors, the incidence of lactic acidosis is reported to be very low when they are used properly. We herein present a case of biguanide-associated severe lactic acidosis complicated with thiamine deficiency that was provoked without predisposing factors for thiamine deficiency. Diabetic patients taking biguanide may be predisposed to thiamine deficiency, even when there is no evidence of risk factors, and the high-dose administration of thiamine may be essential in the treatment of this otherwise under-recognized disorder.