Metformin accumulation: Lactic acidosis and high plasmatic metformin levels in a retrospective case series of 66 patients on chronic therapy

Preadmission metformin use increased the incidence of hyperlactatemia at admission and 30-day in-hospital mortality among T2D patients with heart disease at high risk of hypoxia

BACKGROUND

Surprisingly, despite the high prevalence of metformin use in type 2 diabetes (T2D) patients with heart disease, limited safety data is available regarding metformin use in patients with acute and critical heart disease.

METHODS

In this single-center retrospective study, patients admitted to the cardiology department for heart failure (HF) or acute coronary syndrome (ACS) between December 2013 and December 2021 and who underwent arterial blood gas analysis at admission with an estimated glomerular clearance rate of ≥45 ml/min/1.73 m2 were identified. The incidences of hyperlactatemia, acidosis, and 30-day in-hospital mortality were compared between preadmission metformin users and nonusers.

RESULTS

Of 526 admissions, 193/193 metformin users/nonusers were selected in a propensity score-matched model. Metformin users had greater lactate levels (2.55 ± 2.07 mmol/l vs. 2.00 ± 1.80 mmol/l P < 0.01), a greater incidence of hyperlactatemia [odds ratio (OR) = 2.55; 95% confidence interval (CI), 1.63-3.98; P < 0.01] and acidosis (OR = 1.78; 95% CI, 1.00-3.16; P < 0.05) at admission and a greater incidence of in-hospital mortality (OR = 3.83; 95% CI, 1.05-13.94; P < 0.05), especially those with HF/acute myocardial infarction, elderly age, or without preadmission insulin use.

CONCLUSIONS

Our results suggest that, compared to metformin nonusers, preadmission use of metformin may be associated with a greater incidence of hyperlactatemia and acidosis at admission and greater 30-day in-hospital mortality among T2D patients with HF or ACS at high risk of hypoxia, particularly those without preadmission insulin use. The safety of metformin in this population needs to be confirmed in prospective controlled trials.

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.

A Case of Metformin-Associated Lactic Acidosis Complicated by Acute Liver Failure, Acute Renal Failure, and Shock

Metformin is an oral antihyperglycemic agent used for type 2 diabetes mellitus (T2DM) management and is considered to be the first-line treatment for diabetic patients. It works by improving insulin sensitivity, reducing intestinal absorption, and decreasing glucose production in the liver, leading to decreased blood glucose levels. It is generally considered a safe drug; however, it is associated with an uncommon but serious side effect known as metformin-associated lactic acidosis (MALA), a potentially life-threatening condition. Patients with renal failure and liver disease are at high risk of developing MALA; therefore, the medication should be used cautiously in these patients. The diagnosis of MALA requires high suspicion from the physician of this specific entity; otherwise, it may be easily missed. Herein, we report a case of a 63-year-old female with alcoholic liver disease on metformin who was found to have MALA complicated by acute decompensated liver failure, renal failure, and shock.

Chronic kidney disease progression in diabetic patients: Real world data in general practice

Aims

the aim of the study was to analyze glomerular filtration ratio (GFR) changes in diabetic patients assisted by General Practitioners (GPs) evaluating the risk factors related to glomerular function.

Methods

patients with diabetes with at least three recorded values of creatinine were recruited in the study and GFR values were estimated. The quarterly percentage change in GFR for each patient was estimated. Nephrotoxic drugs were identified, and glucose-lowering drugs use was described. Linear regression analyses were performed to identify eGFR changes predictors.

Results

a total of 545 patients with diabetes were selected. According to the last eGFR values 64 (11.7 %) patients were classified in G1 stage, 277 (50,8 %) in G2, 175 (32.1 %) in G3a, 25 (4.6 %) in G3b and only 4 (0.7 %) in G4. Patients treated with at least one glucose-lowering drugs were 479 (87.9 %), most of them with biguanides (67.0 %). At least one nephrotoxic drug prescription was recorded in 524 (96.1 %) patients; proton pump inhibitors (74.7 %) and NSAIDs (71.6 %) were the most prescription classes. Heart failure, diabetes duration and preserved GFR values were related to reduced eGFR values.

Conclusions

patients with diabetes should be more carefully observed regardless of kidney risk factors and GFR values in clinical practice.

Metformin-Associated Lactic Acidosis-Is This on Your Radar?

BACKGROUND

Metformin is a biguanide hyperglycemic agent used to manage non-insulin-dependent diabetes mellitus. Adverse reactions include mainly mild gastrointestinal adverse effects, but severe complications, such as metformin-associated lactic acidosis (MALA) can occur. Metformin is excreted renally and, therefore, not recommended in patients with renal impairment. The reported incidence of MALA is 3 cases per 100,000 patient-years.

CASE REPORT

A 79-year-old woman with a complex medical history, including end-stage renal disease on dialysis and type 2 diabetes, presented to the emergency department (ED) for altered mental status. Prior to arrival, she was found to be hypoglycemic. Her laboratory results were significant for creatinine of 6.56 mg/dL and an anion gap of 52 mmol/L. The venous blood gas revealed a venous pH of 6.857 [reference range (7.32-7.43)], pCO2 of 15.9 mm Hg (40.6-60 mm Hg), HCO3 of 2.7 mmol/L (21-30 mmol/L), lactate of 27 mmol/L (0.5-2 mmol/L), and ammonia of 233 µmol/L. The patient was dialyzed emergently in the ED; repeat laboratory test results showed blood urea nitrogen of 10 mg/dL, creatinine of 1.65 mg/dL, carbon dioxide of 26 mmol/L, and anion gap of 13 mmol/L. The repeat ammonia was 16 µmol/L. The patient's metabolic encephalopathy resolved, and she was discharged home on hospital day 3. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: MALA has a high mortality rate (36%). Laboratory markers have not been found to be a reliable predictor of mortality. Sodium bicarbonate is controversial, but a pH < 7.15 indicates consideration of its use. A pH < 7.1 and a lactate level > 20 mmol/L indicate the need for emergent hemodialysis. Prompt recognition and management in the ED with early hemodialysis can result in good patient outcomes, with a return to their baseline function despite severe laboratory findings.

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-Associated Lactic Acidosis in Individuals Without Chronic Kidney Disease on Therapeutic Dose: A Case Report

Metformin-associated lactic acidosis (MALA) is a severe side effect of metformin treatment. We encountered an exceedingly rare case of MALA in a patient taking metformin at recommended doses who had no risk factors except for advanced age. A 77-year-old male with a diagnosis of lactic acidosis was referred to our facility. He was taking 250 mg/day of metformin for diabetes. Although he had no pre-existing chronic kidney disease, he developed acute kidney injury upon admission, leading to the diagnosis of MALA based on the test results and history of metformin use. His lactic acidosis improved without extracorporeal treatment through metformin discontinuation and proper circulatory management. When encountering patients with unexplained lactic acidosis, it is important to consider MALA as part of the differential diagnosis and to confirm the patient's medication history. Specifically, when metformin use is identified, attention should be directed toward the potential for MALA.

Arterial Blood Gases and Acid-Base Regulation

Disorders of acid-base status are common in the critically ill and prompt recognition is central to clinical decision making. The bicarbonate/carbon dioxide buffer system plays a pivotal role in maintaining acid-base homeostasis, and measurements of pH, PCO2, and HCO3 - are routinely used in the estimation of metabolic and respiratory disturbance severity. Hypoventilation and hyperventilation cause primary respiratory acidosis and primary respiratory alkalosis, respectively. Metabolic acidosis and metabolic alkalosis have numerous origins, that include alterations in acid or base intake, body fluid losses, abnormalities of intermediary metabolism, and renal, hepatic, and gastrointestinal dysfunction. The concept of the anion gap is used to categorize metabolic acidoses, and urine chloride excretion helps define metabolic alkaloses. Both the lungs and kidneys employ compensatory mechanisms to minimize changes in pH caused by various physiologic and disease disturbances. Treatment of acid-base disorders should focus primarily on correcting the underlying cause and the hemodynamic and electrolyte derangements that ensue. Specific therapies under certain conditions include renal replacement therapy, mechanical ventilation, respiratory stimulants or depressants, and inhibition of specific enzymes in intermediary metabolism disorders.

Ultrafast Measurement of Metformin in the Clinical Setting Using Probe Electrospray Ionization Mass Spectrometry

Metformin (MtF) is a treatment used for type 2 diabetes. Lactic acidosis (LA) is a frequent complication that can be either induced by or associated with elevated MtF plasma concentrations. When coupled with a mass spectrometry (MS) system, the probe electrospray ionization (PESI) method allows direct and rapid analysis of different types of matrices without pretreatment. In this study, we developed a PESI-MS method for the determination of MtF in plasma. We used a tandem mass spectrometer equipped with a PESI source in the reaction monitoring mode for the quantitation of MtF. MtF-d6 was chosen as the internal standard (IS), following an isotope dilution (ID) approach. The method was fully validated with six concentration levels (0.5-50 mg/L). The matrix effect was evaluated for each level, and the specificity was tested with a mix of potential co-medications. Using patient samples, the performance was compared with two classical LC-MS-MS and LC-diode array detector (DAD) methods used in external labs. Sample preparation consisted in mixing 10 µL plasma in 1,000 µL ethanol/ammonium formate buffer including MtF-d6 at a fixed concentration of 5 mg/L. The total run time was 0.31 min. ID gave satisfactory results of accuracy and precision (min-max: -12.1 to 15.8% and 1.0-17.1%, respectively). The matrix effect was fully corrected by the internal standard (bias < 1%). The specificity study also reported satisfactory results. Finally, in a representative group of 29 patients (55% with a concentration <5 mg/L, 38% with a concentration >5 mg/L and 7% not detected), we observed almost identical results when comparing LC-DAD and LC-MS-MS to PESI-MS (r2 > 0.99). We propose a specific, sensitive, accurate and ultrafast solution for the measurement of MtF in patient plasma, with no sample preparation or calibration curve building. This could be helpful in a core lab when rapid diagnosis of LA is needed.

Metformin-NSAIDs Molecular Salts: A Path towards Enhanced Oral Bioavailability and Stability

According to the World Health Organization, more than 422 million people worldwide have diabetes. The most common oral treatment for type 2 diabetes is the drug metformin (MTF), which is usually formulated as a hydrochloride to achieve higher water solubility. However, this drug is also highly hygroscopic, thus showing stability problems. Another kind of worldwide prescribed drug is the non-steroidal anti-inflammatory drug (NSAID). These latter, on the contrary, show a low solubility profile; therefore, they must be administered at high doses, which increases the probability of secondary effects. In this work, novel drug-drug pharmaceutical solids combining MTF-NSAIDs have been synthesized in solution or by mechanochemical methods. The aim of this concomitant treatment is to improve the physicochemical properties of the parent active pharmaceutical ingredients. After a careful solid-state characterization along with solubility and stability studies, it can be concluded that the new molecular salt formulations enhance not only the stability of MTF but also the solubility of NSAIDs, thus giving promising results regarding the development of these novel pharmaceutical multicomponent solids.

Mechanisms of cancer cell killing by metformin: a review on different cell death pathways

Cancer resistance to anti-tumour agents has been one of the serious challenges in different types of cancer treatment. Usually, an increase in the cell death markers can predict a higher rate of survival among patients diagnosed with cancer. By increasing the regulation of survival genes, cancer cells can display a higher resistance to therapy through the suppression of anti-tumour immunity and inhibition of cell death signalling pathways. Administration of certain adjuvants may be useful in order to increase the therapeutic efficiency of anti-cancer therapy through the stimulation of different cell death pathways. Several studies have demonstrated that metformin, an antidiabetic drug with anti-cancer properties, amplifies cell death mechanisms, especially apoptosis in a broad-spectrum of cancer cells. Stimulation of the immune system by metformin has been shown to play a key role in the induction of cell death. It seems that the induction or suppression of different cell death mechanisms has a pivotal role in either sensitization or resistance of cancer cells to therapy. This review explains the cellular and molecular mechanisms of cell death following anticancer therapy. Then, we discuss the modulatory roles of metformin on different cancer cell death pathways including apoptosis, mitotic catastrophe, senescence, autophagy, ferroptosis and pyroptosis.

Relationship Between Plasmatic Metformin Concentration and Renal Replacement Therapy: A Multicenter Cohort Study

BACKGROUND

Metformin is the first-line treatment used for type 2 diabetes mellitus for more than 60 years. Metformin-associated lactic acidosis is the most serious adverse effect of metformin and is most widely defined as metabolic acidosis with elevated lactate levels in the presence of metformin. However, there is no consensus regarding the role of metformin in metformin-associated lactic acidosis onset. This study aimed to determine the metformin toxicity threshold (the metformin plasma concentration that predicts the occurrence of lactic acidosis) and the metformin dialysis threshold (the metformin plasma concentration strongly correlated with dialysis introduction).

METHODS

This was a retrospective multicenter cohort study conducted from January 1, 2013, to December 31, 2020. All consecutive adult patients with at least one metformin-detectable blood concentration measurement were included.

RESULTS

In total, 169 patients (92 men; mean age, 70 ± 11 years) were included in this study. A receiver operating characteristic analysis using Youden index showed that a metformin plasma concentration threshold of 17.9 mg/L was associated with lactic acidosis (sensitivity: 43.8%; specificity: 90.5%). Another receiver operating characteristic analysis using Youden index showed that a metformin plasma concentration threshold of 17.5 mg/L was associated with dialysis (sensitivity, 53.0%; specificity: 94.2%).

CONCLUSIONS

The retrospective study design, lack of clinical data, and selection bias (patients in whom metformin was prescribed owing to pathological conditions) were major limitations, resulting in only preliminary findings. However, this study could serve as a basis for future prospective clinical studies to evaluate the use of these clinical threshold values as therapeutic guides.

Three Cases of Lactic Acidosis Caused by Biguanides

Biguanides may cause lactic acidosis (LA) in elderly patients. We report three cases of LA after the administration of biguanides. Case 1 was an 85-year-old man with no hepatic dysfunction who was discharged, case 2 was a 67-year-old man with no hepatic dysfunction who was discharged, and case 3 was a 77-year-old woman with hepatic dysfunction who died. Therefore, caution should be exercised in administering biguanides to elderly patients with hepatic dysfunction.

Continuous extracorporeal clearance in metformin-associated lactic acidosis and metformin-induced lactic acidosis: a systematic review

INTRODUCTION

Metformin poisoning with lactic acidosis is an uncommon yet clinically serious condition related to the inhibition of normal aerobic metabolism. Toxicity may occur after an acute overdose although it is much more common after a systemic insult, such as acute kidney injury, in the setting of chronic use. Hemodialysis is currently the preferred extracorporeal treatment modality (Grade 1D evidence) although some patients may be too hemodynamically unstable to tolerate it. Continuous renal replacement therapy is considered an alternative if hemodialysis is unavailable but an evaluation of survival amongst this specific treatment class is lacking.

OBJECTIVES

To assess overall survival and provide an updated review of the toxicokinetic elimination parameters of patients receiving continuous renal replacement therapy for metformin poisoning.

METHODS

A comprehensive search was performed using the EMBASE and MEDLINE libraries from inception until November 30, 2021. Data was extracted and findings were summarized. Toxicokinetic parameters were analyzed and confirmed for accuracy when data permitted.

RESULTS

Eighty-three reports met inclusion criteria. These consisted of only low-quality evidence including 75 case reports, four case series, and four descriptive retrospective reviews. Overall survival among patients suffering from metformin toxicity who received continuous extracorporeal treatment was 85.8%. When stratified between metformin-induced lactic acidosis and metformin-associated lactic acidosis, survival was 75.0% and 87.4%, respectively. Available continuous renal replacement therapy toxicokinetic parameters were quite heterogeneous. Errors in previously published toxicokinetic calculations were noted in only two instances. The overall average and median peak metformin concentrations were 70.5 mg/L and 41.9 mg/L, respectively. The average and median extracorporeal clearance rates were 39.0 mL/min and 42.1 mL/min (range 9.0-58.7 mL/min). The average and median elimination half-life parameters were 27.5 h and median 23.0 h. Elimination half-life ranged from seven to 74 h. There was no meaningful relationship between peak metformin concentration and continuous extracorporeal treatment half-life at lower concentrations, though at very high concentrations (over 200 mg/L), there was a trend towards a half-life below 20 h. There is insufficient data to robustly evaluate overall survival in relation to the extracorporeal clearance rate. Finally, there was no relevant relationship between maximal lactate concentration and survival, nor nadir pH and survival, for patients with either type of metformin toxicity.

CONCLUSIONS

This retrospective systematic analysis of published cases treating metformin related lactic acidosis with continuous renal replacement therapy notes an overall slightly greater survival percentage compared to previous publications of individuals requiring any modality of renal replacement therapy. Because of publication bias, these results should be interpreted with caution and serve as hypothesis generating for future research. Prospective study focusing on the most clinically meaningful endpoint - survival - will help elucidate if continuous modalities are non-inferior to intermittent hemodialysis in metformin toxicity.

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.

Metformin-associated lactic acidosis and factors associated with 30-day mortality

Background

Metformin-associated lactic acidosis (MALA) is a rare event but underrecognition may lead to unfavorable outcomes in type 2 diabetes patients. While many risk factors of MALA have been identified, how to reduce mortality from MALA is a matter of debate. This study aimed to explore the factors associated with 30-day mortality amongst MALA patients.

Methods

An observational study enrolled patients diagnosed with MALA between January 2014 and December 2017. MALA was defined by a history of metformin administration, metabolic acidosis (arterial blood gas pH <7.35 or HCO₃ <15 mmol/L), and elevated plasma lactate level (>5 mmol/L). We examined risk factors including age, sex, underlying diseases, current medications, blood tests, disease severity, and dialysis data. Mortality status was identified from medical records or report on telephone.

Results

We included 105 MALA patients. Most patients (95.2%) were diagnosed acute kidney injury stage 3 according to KDIGO 2012 definition. The 30-day mortality rate was 36.2% and dialysis rate was 85.7%. The survivors had higher proportions of underlying chronic kidney disease, presence of metabolic acidosis, receiving renal replacement therapy within 6 hours, and haemodialysis, whereas the non-survivors had higher percentage of hypertension and disease severity. Lower APACHE II score (HR = 0.95; 95%CI, 0.91–0.99; p = 0.038), time to dialysis < 6 hours (0.31; 0.14–0.69; 0.004), and haemodialysis (0.20;0.06–0.67; 0.010) were associated with lower 30-day mortality, using multivariate Cox-regression analysis.

Conclusions

Mortality rate amongst patients with MALA was high. Early dialysis treatment within 6 hours after admission and haemodialysis were independently associated with lower 30-day mortality. The large scale, well-designed studies need to confirm these encouraging results.

Clinical presentations and prognosis of metformin-associated lactic acidosis patients in the intensive care unit: A 20-year survey

METHODS

We retrospectively analyzed 82 adult patients with MALA admitted to the ICU over 20 years. The association between the clinical parameters and mortality post-MALA was estimated using logistic regression analysis.

RESULTS

Patients with MALA admitted to the ICU presented with clinical symptoms mainly associated with the head (40.24%), chest (41.46%), and abdomen (35.37%). Additionally, the PLL distribution significantly varied with age, APACHE II = Acute Physiology and Chronic Health Evaluation II (APACHE II) score, various laboratory parameters like nadir arterial bicarbonate level, multiple treatment modalities such as renal replacement therapy, and mortality. The overall mortality rate was 17.07%. After adjustment of age and gender, the significant predictors of mortality were APACHE II score, PLL, vasoactive support, ventilator support, and cardiopulmonary resuscitation.

CONCLUSIONS

Despite MALA being a rare event, it is necessary to evaluate its clinical characteristics, especially the associated PLL and mortality. In the current study, higher levels of APACHE II score and PLL show a greater likelihood of mortality in MALA patients.

Case Report: A Case of Encephalopathy Presenting the Lentiform Fork Sign on MRI in a Diabetic Dialysis Patient

Basal ganglia lesions showing an expansile high signal intensity on T2-weighted MRI are termed the lentiform fork sign. This specific finding is mainly observed in diabetic patients with uremic encephalopathy with metabolic acidosis, although there are also reports in patients with ketoacidosis, dialysis disequilibrium syndrome, intoxication, and following drug treatment (e.g., metformin). A 57-year-old Japanese man on chronic hemodialysis for 4 years because of diabetic nephropathy was admitted to our hospital for relatively rapid-onset gait disturbance, severe dysarthria, and consciousness disturbance. Brain T2-weighted MRI showed the lentiform fork sign. Hemodialysis was performed the day before admission, and laboratory tests showed mild metabolic (lactic) acidosis, but no uremia. Surprisingly, metformin, which is contraindicated for patients with end-stage kidney disease, had been prescribed for 6 months in his medication record, and his sluggish speaking and dysarthria appeared gradually after metformin treatment was started. Thus, the encephalopathy was considered to be related to metformin treatment. He received hemodialysis treatment for 6 consecutive days, and his consciousness disturbance and dysarthria improved in 1 week. At the 8-month follow-up, the size of the hyperintensity area on MRI had decreased, while the mild gait disturbance remained. Considering the rapid onset of gait and consciousness disturbance immediately before admission, diabetic uremic syndrome may also have occurred with metformin-related encephalopathy, and resulted in the lentiform fork sign, despite the patient showing no evidence of severe uremia on laboratory data.

A randomized, double-blind clinical trial of a herbal formulation (GlycaCare-II) for the management of type 2 diabetes in comparison with metformin

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a major public health concern with growing prevalence with multiple debilitating complications. GlycaCare-II is a proprietary herbal formulation supplement for T2DM containing extracts of Cinnamomum cassia, Momordica charantia, Pterocarpus marsupium, Gymnema sylvestre, Salacia reticulata, Eugenia jambolana, and a bioavailability enhancer piperine from Piper nigrum.

OBJECTIVE

The antihyperglycemic potential of GlycaCare-II was compared against metformin in a double-blind study.

DESIGN

It was a randomized, two-arm design on prediabetic (N = 29; 12 in metformin and 17 in GlycaCare-II arm, respectively) and newly diagnosed diabetic (N = 40; 16 in metformin and 24 in GlycaCare-II) patients for 120 days.

OUTCOME MEASURES

Changes in diabetic panel glycosylated hemoglobin (HbA1c), fasting blood sugar (FBS), and postprandial blood sugar (PBS) were the primary endpoints. Lipid profile, liver profile, thyroid-stimulating hormone, bilirubin and creatinine were the secondary endpoints.

RESULT

Twice a day treatment for 120 days with GlycaCare-II led to a statistically significant change in HbA1c (p < 0.001), FBS (p < 0.001), PBS (p < 0.001) on both prediabetic and newly diagnosed diabetic patients. GlycaCare-II showed a similar potential as metformin in the treatment of T2DM. In the prediabetic group, both GlycaCare-II and metformin were comparable for all the hyperglycemic index parameters. In the case of newly diagnosed diabetic patients, GlycaCare-II showed a significantly better reduction for PBS (p = 0.026) as compared to metformin, while all other parameters in the diabetic panel were comparable. No adverse events were reported throughout the trial period.

CONCLUSION

These results suggest that GlycaCare-II is effective in managing T2DM in both newly diagnosed diabetic and prediabetic patients.

Drug-Related Problems in Hospitalised Patients with Chronic Kidney Disease: A Systematic Review

INTRODUCTION

Globally, chronic kidney disease (CKD) is one of the leading causes of mortality. Impaired renal function makes CKD patients vulnerable to drug-related problems (DRPs).

AIM

The aim of this systematic review was to investigate the prevalence and nature of DRPs among hospital in-patients with CKD.

METHODS

A systematic review of the literature was conducted using Medline, EMBASE, PsycINFO, Web of Science (Core Collection), CINAHL plus (EBSCO), Cochrane Library (Wiley), Scopus (ELSEVIER) and PubMed (U.S.NLM) from index inception to January 2020. Studies investigating DRPs in hospitalised CKD patients published in the English language were included. Two independent reviewers extracted the data and undertook quality assessment using the Joanna Briggs Institute (JBI) tool.

RESULTS

A total of 2895 unique titles were identified; with 20 meeting the inclusion criteria. DRPs prevalence in CKD was reported between 12 and 87%. The most common DRPs included ineffective treatment, inappropriate drug choice and dosing problems. Antibiotics, H2-antihistamines and oral antidiabetics (metformin) were common drug classes involved in DRPs. Factors associated with DRPs included severity of CKD, the number of medications taken, age, length of hospital stay, and gender.

CONCLUSION

This systematic review provides evidence that DRPs are a frequent occurrence and burden for hospitalised patients with stage 1-4 CKD. Heterogeneity in study design, case detection and definitions are common, and future studies should use clearer definitions and study designs. Protocol Registration: PROSPERO: CRD42018096364.

The Gut Microbiome, Metformin, and Aging

Metformin has been extensively used for the treatment of type 2 diabetes, and it may also promote healthy aging. Despite its widespread use and versatility, metformin's mechanisms of action remain elusive. The gut typically harbors thousands of bacterial species, and as the concentration of metformin is much higher in the gut as compared to plasma, it is plausible that microbiome-drug-host interactions may influence the functions of metformin. Detrimental perturbations in the aging gut microbiome lead to the activation of the innate immune response concomitant with chronic low-grade inflammation. With the effectiveness of metformin in diabetes and antiaging varying among individuals, there is reason to believe that the gut microbiome plays a role in the efficacy of metformin. Metformin has been implicated in the promotion and maintenance of a healthy gut microbiome and reduces many age-related degenerative pathologies. Mechanistic understanding of metformin in the promotion of a healthy gut microbiome and aging will require a systems-level approach. Expected final online publication date for the Annual Review of Pharmacology and Toxicology, Volume 62 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Cholinergic and metabolic effects of metformin in mouse brain

Metformin is widely used as a first-line treatment for type 2 diabetes, but central effects of metformin have received little attention. When metformin (200 mg/kg i.p.) was administered to C57Bl6 mice, metformin concentration in cerebrospinal fluid peaked at 29 μM after 30 min but dropped quickly and was low at 90 min. In mouse hypothalamus sampled by microdialysis, systemically administered metformin caused minor and transient increases of acetylcholine, glucose and lactate while choline levels decreased. When metformin (0.2-10 mM) was locally infused via retrodialysis, there was a short-lasting increase of acetylcholine in the hypothalamus. Extracellular lactate levels in hypothalamus showed a massive increase upon metformin infusion while glucose levels decreased. In isolated mitochondria of mouse brain, metformin inhibited oxygen consumption and the activity of complex I. Inhibition of mitochondrial respiration likely explains lactate formation in the brain during metformin infusion which may cause lactic acidosis during metformin intoxication. The changes of cholinergic activity in the hypothalamus may be associated with appetite suppression observed during metformin treatment.

Counterfeit formulations: analytical perspective on anorectics

Purpose

This paper examines the scope of anorectics in counterfeit weight-reducing formulations and provides insight into the present state of research in determining such adulterants. Analytical techniques utilised in profiling adulterants found in slimming products, including limitations and mitigation steps of these conventional methods are also discussed. The current legal status of the anorectics and analogues routinely encountered in non-prescription slimming formulations is also explored.

Methods

All reviewed literature was extracted from Scopus, Web of Science, PubMed, and Google Scholar databases using relevant search terms, such as, ‘counterfeit drugs’, ‘weight loss drugs’, ‘weight-reducing drugs’, ‘slimming drugs’, ‘anorectic agents’, and ‘counterfeit anorexics’. Legislation related to anorectics was obtained from the portals of various government and international agencies.

Results

Anorectics frequently profiled in counterfeit slimming formulations are mostly amphetamine derivatives or its analogues. Five routinely reported pharmacological classes of adulterants, namely anxiolytics, diuretics, antidepressants, laxatives, and stimulants, are mainly utilised as coadjuvants in fake weigh-reducing formulations to increase bioavailability or to minimise anticipated side effects. Liquid and gas chromatography coupled with mass spectrometric detectors are predominantly used techniques for anorectic analysis due to the possibility of obtaining detailed information of adulterants. However, interference from the complex sample matrices of these fake products limits the accuracy of these methods and requires robust sample preparation methods for enhanced sensitivity and selectivity. The most common anorectics found in counterfeit slimming medicines are either completely banned or available by prescription only, in many countries.

Conclusions

Slimming formulations doped with anorectic cocktails to boost their weight-reducing efficacy are not uncommon. Liquid chromatography combined with mass spectrometry remains the gold standard for counterfeit drug analysis, and requires improved preconcentration methods for rapid and quantitative identification of specific chemical constituents. Extensive method development and validation, targeted at refining existing techniques while developing new ones, is expected to improve the analytical profiling of counterfeit anorectics significantly.

Metformin, chronic nephropathy and lactic acidosis: a multi-faceted issue for the nephrologist

Metformin is currently considered a first-line therapy in type 2 diabetic patients. After issuing warnings for decades about the risks of lactic acidosis in patients with chronic nephropathy, metformin is now being re-evaluated. The most recent evidence from the literature has demonstrated both a low, acceptable risk of lactic acidosis and a series of favorable effects, which go beyond its hypoglycemic activity. Patients treated with metformin show a significant mortality reduction and lower progression towards end-stage renal disease in comparison with those treated with other hypoglycemic drugs. Concerning lactic acidosis, in the last few years it has been shown how lactic acidosis almost always developed when patients kept taking the drug in the face of a concomitant disease or situation such as sepsis, fever, diarrhea, vomiting, which reduced metformin renal clearance. Actually, clearance of metformin is mainly renal, both by glomerular filtration and tubular secretion (apparent clearance 933–1317 ml/min, half-life < 3 h). As regards treatment, in cases of lactic acidosis complicated by acute kidney injury, continuous renal replacement therapy (CRRT) plays a crucial role. Besides the elimination of metformin, CRRT  improves survival by correcting acidosis, electrolyte alterations, and maintaining fluid balance. Lactic acidosis almost always develops because of preventable drug accumulation. Therefore, prevention is a key factor. Patients should be aware that discontinuation for a limited time does not affect their health, even when it may be inappropriate, but it may avoid a serious, potentially fatal adverse event.

Inhibition of EZH2 Enhances the Antitumor Efficacy of Metformin in Prostate Cancer

Upregulation of EZH2 is associated with advanced stage and poor prognosis of prostate cancer; therefore, it is likely to be a promising therapeutic target. Metformin, a drug that has been used to treat type 2 diabetes, was found to have antineoplastic activity in different cancers. Herein, we report that the combination of metformin and the EZH2 inhibitor GSK126 exerts synergistic inhibition on prostate cancer cell growth, both in vitro and in vivo Mechanistically, we identify that metformin can reduce EZH2 expression through upregulating miR-26a-5p, which is antagonized by androgen receptor (AR). Furthermore, we show that AR binds to the promoter of miR-26a-5p and suppresses its transcription. Although metformin can remove AR from the miR-26a-5p promoter, the interaction between AR and EZH2, which usually exists in androgen-refractory prostate cancer cells, strongly impedes the removal. However, GSK126 can inhibit the methyltransferase-dependent interaction between AR and EZH2, thus restoring metformin's efficacy in androgen-refractory prostate cancer cells. Collectively, our finding suggests that the combination of metformin and GSK126 would be an effective approach for future prostate cancer therapy, and particularly effective for AR-positive castration-resistant prostate cancer.

Identifying patients with metformin associated lactic acidosis in the emergency department

Background Metformin associated lactic acidosis (MALA) is a serious adverse event with a high mortality rate of 30-50%. Early recognition of MALA and timely starting treatment may reduce its morbidity and mortality. Objective The aim of this study was to explore clinical parameters to identify patients with MALA in patients with suspected sepsis induced lactic acidosis in the emergency department ED. Setting A retrospective single centre study was conducted at the Deventer Teaching Hospital in the Netherlands. Method Patients with lactate concentration > 4.0 mmol/l admitted at the ED between 2010 and 2017 with suspected sepsis or confirmed MALA and referred to the Intensive Care Unit were included. Baseline characteristics (pH, lactate, creatinine and CRP) of MALA patients were compared with patients with suspected sepsis induced lactic acidosis. Creatinine and lactate concentration were selected as potential relevant parameters. Main outcome measure Sensitivity and specificity of the highest tertiles of the creatinine and the lactate concentrations separately, in combination, and both combined with metformin use, were calculated. Results Thirteen MALA and 90 suspected sepsis induced lactic acidosis patients were included. Lactate (14.7 vs 5.9 mmol/l, p < 0.01) and creatinine concentration (642 vs 174 μmol/l, p < 0.01) were significantly higher in the MALA group and arterial pH (7.04 vs 7.38, p < 0.01) and CRP (90 vs 185 mg/l, p < 0.01) were significantly lower. The combined parameters lactate ≥ 8.4 mmol/l, creatinine ≥ 256 μmol/l had a sensitivity of 85% and a specificity of 95% for identifying MALA in suspected sepsis induced lactic acidosis patients in the ED. When combined with metformin use the specificity increased to 99%. Conclusion When managing lactic acidosis in the ED the diagnosis MALA should be considered in patients with a creatinine concentration ≥ 256 μmol/l and lactate concentration ≥ 8.4 mmol/l.

Is metformin associated with acute kidney injury? A case-control study of patients with type 2 diabetes admitted with acute infection

INTRODUCTION

Despite the long-term renoprotective effects of Metformin, a recent study on data from the U.S. Food and Drug Administration reported a possible nephrotoxic effect, contributing to the development of acute kidney injury (AKI). We investigated the association between metformin and AKI in patients admitted with the AKI-prone condition of acute infection and compared results with corresponding results of other antidiabetics.

METHODS

In a nationwide register-based case-control study, we identified Danish patients with type 2 diabetes hospitalized with acute infection between 2008 and 2018. Cases of AKI had an increase in plasma creatinine ≥  × 1.5 during admission, controls did not. Antidiabetics were identified up to 6 months before admission. Odds ratio (OR) of each antidiabetic was computed in separate multiple logistic regression models adjusted for relevant medication and comorbidities and results compared.

RESULTS

We included 46,811 patients, hereof 9454 AKIs (20%) and 2186 (4.7%) severe AKIs. Overall, 56% were males, median age (IQR) was 73 (65-81). Sixty percent received metformin, 13% sulfonylurea, 31% insulin and 8% dipeptidyl peptidase-4 inhibitors (DPP-4i), with equal distribution between cases and controls. Metformin was associated with increased OR (CI) for AKI, 1.07 (1.02-1.12), equally to sulfonylurea, 1.10 (1.03-1.18) and DPP-4i, 1.11 (1.02-1.20), but not insulin, 0.99 (0.93-1.05). In severe AKI, results for metformin were 1.27 (1.25-1.40) but increased equivalently to other antidiabetics.

CONCLUSIONS

In patients with type 2 diabetes hospitalized with acute infection, metformin was not independently associated with AKI, since other antidiabetics were also significantly associated, indicating confounding by indication.

Case Report: A Case of Encephalopathy Presenting the Lentiform Fork Sign on MRI in a Diabetic Dialysis Patient

Basal ganglia lesions showing an expansile high signal intensity on T2-weighted MRI are termed the lentiform fork sign. This specific finding is mainly observed in diabetic patients with uremic encephalopathy with metabolic acidosis, although there are also reports in patients with ketoacidosis, dialysis disequilibrium syndrome, intoxication, and following drug treatment (e.g., metformin). A 57-year-old Japanese man on chronic hemodialysis for 4 years because of diabetic nephropathy was admitted to our hospital for relatively rapid-onset gait disturbance, severe dysarthria, and consciousness disturbance. Brain T2-weighted MRI showed the lentiform fork sign. Hemodialysis was performed the day before admission, and laboratory tests showed mild metabolic (lactic) acidosis, but no uremia. Surprisingly, metformin, which is contraindicated for patients with end-stage kidney disease, had been prescribed for 6 months in his medication record, and his sluggish speaking and dysarthria appeared gradually after metformin treatment was started. Thus, the encephalopathy was considered to be related to metformin treatment. He received hemodialysis treatment for 6 consecutive days, and his consciousness disturbance and dysarthria improved in 1 week. At the 8-month follow-up, the size of the hyperintensity area on MRI had decreased, while the mild gait disturbance remained. Considering the rapid onset of gait and consciousness disturbance immediately before admission, diabetic uremic syndrome may also have occurred with metformin-related encephalopathy, and resulted in the lentiform fork sign, despite the patient showing no evidence of severe uremia on laboratory data.

A Case Report on Metformin-Associated Lactic Acidosis and Transient Blindness

Metformin is the first-line treatment for any patient with type 2 diabetes. Metformin-associated lactic acidosis and transient blindness have only been reported in some case series and case reports. It is rare and presents especially in patients with underlying chronic kidney disease (CKD) Stage III and above and on high doses of metformin or with a normal dose of metformin and an associated renal injury. We present here a rare and interesting case of something similar. A 77-year-old woman with a past medical history of type 2 diabetes on metformin, obesity status post gastric bypass, CKD Stage III, presented with complaints of nausea, vomiting, confusion, abdominal pain, diarrhea, decreased urine output, sudden visual loss, and a hypoglycemic episode at home. She was hemodynamically stable. Lab work was suggestive of leukocytosis, hyperkalemia, severe high anion gap metabolic and lactic acidosis, acute-on-chronic kidney injury. Findings on the computed tomography (CT) brain, chest radiograph, and CT abdomen and pelvis could not explain the current scenario. She received Ringer’s lactate, a bicarbonate push, and an infusion. Acidosis continued to worsen, she became hypotensive requiring pressor support, and she was immediately taken for hemodialysis. All her symptoms, including vision loss, had improved with a single session of hemodialysis, even before the acidosis had corrected. Work-up for other causes of renal dysfunction came back negative. Metformin was discontinued. She was placed on insulin for her diabetes control.

Discovery of AdipoRon analogues as novel AMPK activators without inhibiting mitochondrial complex I

Activation of AMPK emerges as a potential therapeutic approach to metabolic diseases. AdipoRon is claimed to be an adiponectin receptor agonist that activates AMPK through adiponectin receptor 1 (AdipoR1). However, AdipoRon also exhibits moderate inhibition of mitochondrial complex I, leading to increased risk of lactic acidosis. In order to find novel AdipoRon analogues that activate AMPK without inhibition of complex I, 27 analogues of AdipoRon were designed, synthesized and biologically evaluated. As results, benzyloxy arylamide B10 was identified as a potent AMPK activator without inhibition of complex I. B10 dose-dependently improved glucose tolerance in normal mice, and significantly lowered fasting blood glucose level and ameliorated insulin resistance in db/db diabetic mice. More importantly, unlike the pan-AMPK activator MK-8722, B10 did not cause cardiac hypertrophy, probably owing to its selective activation of AMPK in the muscle tissue but not in the heart tissue. Together, B10 represents a novel class of AMPK activators with promising therapeutic potential against metabolic disease.

Feasibility of Intermittent Hemodialysis in Metformin Toxicity With Shock

BACKGROUND

Metformin toxicity can lead to profound shock and has a high mortality rate. Supportive care and enhanced elimination are the mainstays of therapy. Intermittent hemodialysis (HD) produces a higher clearance of metformin than continuous veno-venous hemofiltration or hemodiafiltration (CVVH/HDF). Nevertheless, CVVH/HDF has been proposed as an alternative in critically ill patients with the suggestion that hypotension may limit the use of HD.

OBJECTIVE

This study sought to analyze the feasibility of performing hemodialysis in patients with persistent shock from metformin toxicity.

METHODS

We performed a 6-year (2012-2017) retrospective chart review of patients with metformin toxicity managed at a large academic institution with a toxicology service. We included patients with persistent shock on vasopressor support who were treated with HD. Baseline characteristics, complications from treatment, timing of dialysis, and differences between mean arterial pressures before, during, and at the end of dialysis were recorded and analyzed.

RESULTS

Despite critical mean peak lactate (23.9 mMol/L [range 17.6-27.9]), pH (6.91 [range 6.78-7.01]), and metformin levels (range 25-58 μg/mL], 6 of 7 patients recovered. All patients required prolonged HD (mean 19 h). Upon completion of HD, hemodynamics had improved (45 mm Hg [95% confidence interval 35-55 mm Hg] vs. 80 mm Hg [95% confidence interval 74-86 mm Hg]) and vasopressor support decreased. Mortality in this patient cohort was 14.3% (1/7).

CONCLUSION

Intermittent HD is feasible in metformin toxicity despite persistent shock and high-dose vasopressor support. Mean arterial pressures improved during the course of HD and high blood flow rates were tolerated.

A Unique Case of Metformin-associated Severe Lactic Acidosis Without Preexisting Renal Disease: Perspectives on Prolonged Dialysis and Education for Prevention

Metabolic acidosis is a common disorder defined by an imbalance in the body's acid-base balance. Identifying the cause of acidosis is critical for its management. We describe a case of acute renal failure with lactic acidosis in a 69-year-old man who was taking metformin for type 2 diabetes. The patient presented with decreased urine output after two weeks of intermittent nausea and vomiting. During this time, the patient had continued to take limited fluids and medication, including lisinopril and metformin. Physical exam on initial evaluation was remarkable only for hypertension and minimal abdominal tenderness. However, laboratory tests revealed a severe lactic acidosis and renal failure with hyperkalemia. The patient had normal renal function and a normal urine albumin level three weeks prior. Broad-spectrum antibiotics and sodium bicarbonate were administered, followed by hemodialysis. During hemodialysis, the patient became hemodynamically unstable, requiring vasopressors. Post-dialysis, the lactic acidosis worsened, prompting the initiation of additional prolonged dialysis during the first hospital day. After the second lengthy dialysis, the patient's condition improved significantly and he was discharged on hospital day 12, with the diagnosis of metformin-associated lactic acidosis (MALA) in the setting of acute tubular necrosis from gastrointestinal fluid loss accompanied by the continued use of an angiotensin-converting enzyme inhibitor. After discharge, his renal function returned to normal. Severe lactic acidosis from metformin is relatively rare. Metformin has a large volume of distribution and accumulates in erythrocytes and intestinal cells, resulting in less efficient removal with dialysis and rebound lactic acidosis. Prolonged dialysis may be necessary for MALA to improve outcomes. Identifying metformin levels may help in diagnosis and management. However, the means to Identify metformin levels are not widely available. Patients receiving metformin should be counseled to stop metformin and seek medical care in the setting of illnesses. This is particularly important given the frequency of metformin prescription and the common use of renin-angiotensin system blockade in patients with type 2 diabetes, which increases the risk of kidney dysfunction.

Extracorporeal treatment of metforminassociated lactic acidosis in clinical practice: a retrospective cohort study

Purpose

To assess whether extracorporeal treatment (ECTR) improves outcome of patients with metformin-associated lactic acidosis (MALA) and to evaluate the clinical applicability of the Extracorporeal Treatments in Poisoning Workgroup (EXTRIP) criteria for starting ECTR in metformin poisoning.

Methods

Patients with metformin serum concentrations above 2 mg/l who were admitted in the Deventer Teaching Hospital between January 2000 and July 2019 and complied with the definition of MALA (pH < 7.35 and lactate concentration > 5 mmol/l) were included. Mortality and clinical parameters of patients treated with ECTR or not were compared. In addition, treatment of MALA in clinical practice was verified against the criteria of EXTRIP.

Results

Forty-two patients were included. Lactate (13.8 versus 10.5 mmol/l, p = 0.01), creatinine (575 versus 254 umol/l, p < 0.01)), metformin (29.4 versus 8.6 mg/l, p < 0.01) concentrations, and vasopressor requirement (72% versus 23%, p < 0.01) were significantly higher in the ECTR-group. Blood pH (7.05 versus 7.19, p = 0.03) and bicarbonate (6 versus 11 mmol/l, p < 0.01) were significantly lower. Mortality, length of hospital stay, and mechanical ventilation requirement were not statistically different. In 83% of patients, treatment of MALA was in accordance with the EXTRIP criteria.

Conclusions

Although there was no statistical benefit in mortality shown from ECTR, ECTR might be lifesaving in MALA, considering the ECTR-group was significantly sicker than the non-ECTR-group.

The majority of patients were treated in line with the EXTRIP criteria. Severity of lactic acidosis and renal impairment were the main indications for initiating ECTR.

Electronic supplementary material

The online version of this article (10.1007/s00228-020-02857-5) contains supplementary material, which is available to authorized users.

A patient with metformin-associated lactic acidosis successfully treated with continuous renal replacement therapy: a case report

BACKGROUND

Metformin has been widely used as a first-line agent to treat type 2 diabetes mellitus. Lactic acidosis is a rare but serious adverse effect in patients treated with metformin. Recent studies noted a correlation between metformin accumulation and lactic acidosis. Continuous renal replacement therapy for the treatment of metformin-associated lactic acidosis has been documented in some case reports; however, there is currently no specific treatment for metformin-associated lactic acidosis.

CASE PRESENTATION

A 70-year-old Japanese woman with type 2 diabetes mellitus presented to an emergency room with metformin-associated lactic acidosis. She was found to be hypotensive and laboratory examinations revealed severe lactic acidosis: pH 6.618, partial pressure of carbon dioxide in arterial blood 17.3 mmHg, bicarbonate 1.7 mmol/L, and lactate 18 mmol/L. Severe acidemia persisted despite supportive care including intravenously administered fluids, sodium bicarbonate, antibiotics, and vasopressors. Continuous renal replacement therapy was initiated in our intensive care unit. After dialysis for 3 days, her lactate level and pH value completely normalized. The concentration of metformin detected was 77.5 mg/L, which is one of the highest in metformin-associated lactic acidosis successfully treated without overdose.

CONCLUSIONS

The present case had one of the highest metformin concentrations in metformin-associated lactic acidosis successfully treated with continuous renal replacement therapy, and serum metformin concentrations may be useful for the diagnosis of metformin-associated lactic acidosis. Metformin-associated lactic acidosis is a rare but important etiology of lactic acidosis. Continuous renal replacement therapy is advantageous for the treatment of hemodynamically unstable patients with metformin-associated lactic acidosis.

Intoxication à la metformine

La metformine, seul représentant disponible en France de la classe des biguanides, est un médicament antidiabétique largement prescrit. L’effet thérapeutique bénéfique du contrôle glycémique obtenu par inhibition de la néoglucogenèse est objectivé par une réduction de la morbimortalité chez les patients diabétiques de type 2. Néanmoins, la metformine affecte aussi le métabolisme du lactate en augmentant sa production par la cellule. Ainsi, l’effet secondaire le plus redouté est l’acidose lactique associée à la metformine (metformin-associated lactic acidosis [MALA]). Celle-ci est liée à une augmentation brutale de la concentration en metformine dans le sang et dans les tissus, que ce soit après ingestion d’une grande quantité de médicament ou plus souvent dans les suites d’une insuffisance rénale aiguë chez un patient traité au long cours. Dans ce contexte d’acidose métabolique majeure avec hyperlactatémie, la sévérité des défaillances d’organes conditionne le pronostic. La prise en charge thérapeutique est symptomatique avec recours précoce à une épuration extrarénale dans les formes sévères ou ne répondant pas au traitement initial. La prévention de la MALA repose avant tout sur le respect des contreindications de la metformine chez les patients diabétiques.

Transient Blindness in a Patient with Severe Metformin-Associated Lactic Acidosis (MALA)

A 68-year-old man presented at the emergency room with sudden blindness. The day before, he had eaten sashimi and eel and drank alcohol for dinner. He experienced nausea, vomiting, and dizziness afterward. His medical history included hypertension and diabetes, and the latter was treated with metformin. Initial laboratory tests revealed severe metabolic acidosis (lactic acidosis). Massive hydration and intravenous sodium bicarbonate replacement therapies were initiated, but severe metabolic acidosis (lactic acidosis) did not resolve, in turn, leading to hemodialysis, which decreased metabolic acidosis. The patient's blindness improved, and his vision gradually recovered. As it is not easy to distinguish between blindness related to metformin-associated lactic acidosis (MALA) and blindness related to other causes, rapid correction of metabolic acidosis through hemodialysis might be helpful in differentiating this from of blindness from blindness related to other causes.

The Biguanides Metformin and Buformin in Combination with 2-Deoxy-glucose or WZB-117 Inhibit the Viability of Highly Resistant Human Lung Cancer Cells

The biguanides metformin (MET) and to a lesser extent buformin (BUF) have recently been shown to exert anticancer effects. In particular, MET targets cancer stem cells (CSCs) in a variety of cancer types but these compounds have not been extensively tested for combination therapy. In this study, we investigated in vitro the anticancer activity of MET and BUF alone or in combination with 2-deoxy-D-glucose (2-DG) and WZB-117 (WZB), which are a glycolysis and a GLUT-1 inhibitor, respectively, in H460 human lung cancer cells growing under three different culture conditions with varying degrees of stemness: (1) routine culture conditions (RCCs), (2) floating lung tumorspheres (LTSs) that are enriched for stem-like cancer cells, and (3) adherent cells under prolonged periods (8-12 days) of serum starvation (PPSS). These cells are highly resistant to conventional anticancer drugs such as paclitaxel, hydroxyurea, and colchicine and display an increased level of stemness markers. As single agents, MET, BUF, 2-DG, and WZB-117 potently inhibited the viability of cells growing under RCCs. Both MET and BUF showed a strong synergistic effect when used in combination with 2-DG. A weak potentiation was observed when used with WZB-117. Under RCCs, H460 cells were more sensitive to MET and BUF and WZB-117 compared to nontumorigenic Beas-2B cells. While LTSs were less sensitive to each single drug, both MET and BUF in combination with 2-DG showed a strong synergistic effect and reduced cell viability to similar levels compared to the parental H460 cells. Adherent cells growing under PPSS were also less sensitive to each single drug, and MET and BUF showed a strong synergistic effect on cell viability in combination with 2-DG. Overall, our data demonstrates that the combination of BGs with either 2-DG or WZB-117 has “broad-spectrum” anticancer activities targeting cells growing under a variety of cell culture conditions with varying degrees of stemness. These properties may be useful to overcome the chemoresistance due to intratumoral heterogeneity found in lung cancer.

Metformin-associated Severe Lactic Acidosis in the Setting of Acute Kidney Injury

Metformin is a first-line biguanide agent for the treatment of diabetes mellitus. It has been known to be associated with lactic acidosis. This side effect especially worsens when being used with other medications affecting the kidney such as angiotensin-converting enzyme inhibitors (ACEi) and loop diuretics. This is a case of a 63-year-old male who suffered from metformin-induced lactic acidosis and underwent hemodialysis for treatment.

Succinate and the shortcut to the cure of metformin-induced lactic acidosis

Inhibition of the respiratory chain complex I plays a key role in the pathogenesis of metformin-induced lactic acidosis. In a work recently published in this journal, a novel cell-permeable succinate prodrug (NV118) increased in vitro mitochondrial oxygen consumption coupled with energy production and decreased lactate production in intact human platelets intoxicated with metformin. This result was interpreted in light of a "bypass" strategy. NV118 entered platelets and released succinate in their cytoplasm; succinate in turn donated electrons to complex II and thus reactivated the flow of electrons to the distal part of the respiratory chain independent of complex I. Herein, I will (1) comment on these findings; (2) highlight the potential therapeutic application of succinate in other critical conditions accompanied by complex I inhibition, including sepsis, traumatic brain injury, and inherited neurological disorders; and (3) examine the most important issues that remain to be solved to transfer these observations to the bedside.

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.

Combination Therapies Using Metformin and/or Valproic Acid in Prostate Cancer: Possible Mechanistic Interactions

Prostate cancer (PCa) is the most frequent cancer in men. The evolution from local PCa to castration-resistant PCa, an end-stage of disease, is often associated with changes in genes such as p53, androgen receptor, PTEN, and ETS gene fusion products. Evidence is accumulating that repurposing of metformin (MET) and valproic acid (VPA) either when used alone, or in combination, with another therapy, could potentially play a role in slowing down PCa progression. This review provides an overview of the application of MET and VPA, both alone and in combination with other drugs for PCa treatment, correlates the responses to these drugs with common molecular changes in PCa, and then describes the potential for combined MET and VPA as a systemic therapy for prostate cancer, based on potential interacting mechanisms.

Lactate Levels with Chronic Metformin Use: A Narrative Review

Metformin has been associated with lactic acidosis. Lactate levels are not commonly tested in clinical practice, and it is unclear to what extent metformin would typically increase lactate levels with chronic use. The aim of this review was to determine whether regular monitoring of the plasma lactate level would be beneficial in avoiding lactate accumulation and, ultimately, minimising the incidence of lactic acidosis in metformin-treated patients.A comprehensive search of PubMed, Embase, Web of Science, Cochrane and International Pharmaceutical Abstracts databases covering the period up to 30 May 2017 was performed. Search terms included combinations of terms and keywords, including "metformin", "lactate", "lactic acid" and "lactic acidosis". Cases series of lactic acidosis or metformin-associated lactic acidosis were excluded.Of 1539 potentially relevant articles, a total of 52 reported lactate levels from routine/regular pathological tests in metformin users. The studies were subdivided into four themes, regarding metformin usage and the reported lactate levels in patients who: (1) did not have contraindications to the use of metformin; (2) had contraindications, or renal impairment but without other contraindications; (3) exercised; or (4) also received any nucleoside reverse transcriptase inhibitor. Studies have reported that metformin treatment could increase lactate level of users. However, most results showed that the lactate level remained in the normal range.No definitive conclusions on the benefits of regular lactate monitoring in patients taking metformin can be made. Future research on larger populations focusing on the measurement of lactate levels with continuous metformin use is warranted.

Metformin associated lactic acidosis: a case series of 28 patients treated with sustained low-efficiency dialysis (SLED) and long-term follow-up

BACKGROUND

Metformin associated lactic acidosis (MALA) is a well-known serious side effect of biguanides. However, the best treatment strategy remains a matter of debate. In the last 14 years, we observed a significant increase in hospitalizations for MALA to our Center. We report the outcomes of our clinical and therapeutic approach.

METHODS

This is a single-center case series. Twenty-eight patients affected with MALA and acute kidney failure admitted between January 2000 and September 2014 were included. We analyzed comorbidities, laboratory tests and clinical parameters at admission, at 36 h and at discharge. All patients were treated with sustained low-efficiency dialysis (SLED) until normalization of serum lactate (≤ 3 mmol/L), bicarbonate (between 20 and 25 mmol/L) and potassium (between 4.0 and 5.1 mmol/L).

RESULTS

The mortality rate was 21.4%, with all of the events occurring within 24 h from admission, and before or during the first hemodialysis treatment. Precipitating causes included; acute dehydration (86.4%), systemic inflammatory response syndrome (SIRS) (57.1%), sepsis (10.7%), nephrolithiasis (14.6%) and exposure to iodinated contrast (7.1%). No further episodes of lactic acidosis were described after discontinuing the drug over a mean follow-up of 27.2 months. Furthermore, while in 2010, we had a peak incidence of MALA of 76.8 cases per 100,000 patients on metformin, this rate fell after an education campaign conducted by specialists on the proper usage of metformin in patients at risk of MALA. Although the fall in incidence after the educational program was not necessarily causal, in 2014 the incidence was 32.9/100,000.

CONCLUSIONS

We report an improved mortality rate in patients affected with MALA and acute kidney injury treated with SLED compared with other series published in literature. Rapid introduction of effective hemodialysis is critical in improving outcomes.