Mortality rate in so-called “metformin-associated lactic acidosis”: a review of the data since the 1960s

[Lactic acidosis associated with metformin: A case series from the Saint-Denis hospital]

INTRODUCTION

Metformin is a first line treatment for type II diabetes. Cases of metformin-associated lactic acidosis are regularly reported. A direct causal link between metformin overdose and lactic acidosis is not clearly established. The aim of this study is to describe cases of metformin-associated lactic acidosis, to assess their vital et renal prognosis, and to analyze the correlations between metforminemia, lactacidemia, pH and death.

METHODS

Cases of metformin-associated lactic acidosis from a single hospital center in Saint-Denis, France, between 2010 and 2022 were analyzed. Inclusion criteria were patients aged 18 or older, treated with metformin, metabolic acidosis with a pH inferior to 7.35 and lactacidemia superior to 5mmol/l.

RESULTS

Twenty-eight patients were included. Median age was 65 years old. Voluntary intoxication was present in 17% of cases. Metformin was contraindicated in 39% of cases. All patients presented with acute kidney injury at admission. Mortality rate was 7%. No factor was associated with death in the univariate analysis. Correlation between pH, lactacidemia, creatininemia and glycated hemoglobin was found. There was no correlation between metforminemia and lactacidemia.

CONCLUSION

Metformin-associated lactic acidosis is a rare complication. Its prognosis is inconstant, varying with the presence or absence of a severe disease causing the overdose. No association was found between clinical data, biological data and death.

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.

Current status and frontier tracking of clinical trials on Metformin for cancer treatment

PURPOSE

Metformin has been used clinically for more than six decades. Over time, numerous remarkable effects of metformin beyond the clinic have been discovered and discussed. Metformin has been shown to have a favorable impact on cancer therapy in addition to its clinically recognized hypoglycemic effect. However, the antitumor efficacy of metformin in humans has not been clearly demonstrated yet. Hence, a systematic analysis of the existing trials is necessary.

METHODS

Here, we retrieved clinical trials from the Clinical Trials.gov database to overview the clinical development of metformin for the treatment of cancer, analyze existing clinical results, and summarize some promising applications for specific cancer therapies.

RESULTS

The potential application of metformin contains three directions: Firstly, improvement of metabolic factors associated with treatment effects, such as insulin resistance and peripheral neuropathy. Secondly, in combination with immune checkpoint blockade effects. Finally, use it for the endocrine treatment of hormone-dependent cancers.

CONCLUSION

Although the outcomes of metformin as a repurposed agent in some trials have been unsatisfactory, it still has the potential to be used in select cancer therapy settings.

Metformin-Induced Eosinophilic Interstitial Lung Disease

Metformin, a mainstay treatment for type two diabetes mellitus has several side effects, ranging from mild to life-threatening ones. One report has found the combination of metformin/glibenclamide a culprit for interstitial lung disease. Other studies have shown that metformin has a protective effect on the lungs. We report a rare case of a 64-year-old male who presented with progressive dyspnea while he was on metformin alone. He was diagnosed with eosinophilic interstitial lung disease (ILD). This was confirmed by a pulmonary function test (PFT), high-resolution chest computed tomography scan (HRCT), and bronchoscopy with bronchoalveolar lavage (BAL). Known causes for eosinophilic pneumonia were excluded, and the patient's condition improved significantly after withdrawing metformin. We report this case due to the rarity of the condition. In fact, this is the only case in the literature, of metformin as the sole agent causing eosinophilic pneumonitis.

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.

A rare case report of combined metformin-associated lactic acidosis and diabetic ketoacidosis

Background

Triad of diabetic ketoacidosis (DKA) comprises of hyperglycemia with serum glucose > 11 mmol/L, high anion gap metabolic acidosis and ketonemia. Hyperlactemia is often noted in patients with DKA. Metformin use is one of the risk factors of hyperlactemia, resulting in high anion gap metabolic acidosis, known as metformin associated lactic acidosis (MALA). This report is of a 60-year-old woman with type 2 diabetes mellitus who presented with combined metformin-associated lactic acidosis MALA and DKA.

Case presentation

A 60-year-old diabetic female presented to the emergency department with complaints of abdominal pain, vomiting and diarrhea. She was on metformin for the last 10 years, but despite compliance to medications, her HbA1c was 14.1. With an aim to improve her glycemic control, linagliptin 5 mg once a day was added 1 month ago. Initial investigations in ED including arterial blood gas analysis revealed metabolic acidosis, ketosis, hyperlactemia, and acute kidney injury. In view of metabolic acidosis and ketosis with elevated blood glucose level, she was diagnosed to have DKA. Compared to isolated DKA, patients with combined MALA and DKA have severe metabolic acidosis, a greater degree of hyperlactatemia but less extensive ketoacidosis. Hence, she was diagnosed to have combined MALA and DKA. She was admitted to intensive care unit and treated with intravenous fluids, insulin infusion, and continuous renal replacement therapy. Her metabolic acidosis, hyperlactemia, and kidney injury resolved and she was discharged well.

Conclusion

This report has shown the importance of rapid diagnosis and management of the rare and challenging diagnosis of combined MALA and DKA. The main goal of therapy is preventing hyperglycemia and ketosis, resolution of metabolic acidosis, and removal of accumulated metformin using intensive therapies like aggressive fluid resuscitation and early initiation of renal replacement therapy. Adjustment of dose of medications is needed to avoid this complication.

Metformin toxicity: A meta-summary of case reports

BACKGROUND

Metformin is arguably the most commonly prescribed oral hypoglycemic agent for the management of diabetes. Due to the lack of randomized control trials, most of the data pertaining to the clinical course, therapeutic interventions and outcomes of patients with metformin induced toxicity has come from case reports or series.

AIM

To analyse the symptomology, clinical interventions and outcomes of patients presenting with severe metformin toxicity by reviewing the published case reports and series.

METHODS

We performed a systematic search from PubMed, Science Direct, Reference Citation Analysis (https://www.referencecitationanalysis.com/) and Google Scholar databases using the terms “metformin” AND “toxicity” OR “overdose” OR “lactic acidosis” OR “hyperlactatemia”. The inclusion criteria were: (1) Case reports or case series with individual patient details; and (2) Reported toxicity or overdose of metformin in adults, published in the English language. Data regarding baseline demographics, clinical presentation, therapeutic interventions, intensive care unit course and overall outcome were collected.

RESULTS

Two hundred forty-two individual cases were analysed, from 158 case reports and 26 case series, with a cumulative mortality of 19.8%. 214 (88.4%) patients were diabetics on metformin. 57 (23.6%) had acute ingestion, but a great majority (76.4%) were on metformin in therapeutic doses when they developed toxicity. Metformin associated lactic acidosis (MALA) was the most commonly reported adverse effect present in 224 (92.6%) patients. Most of the patients presented with gastrointestinal and neurological symptoms and a significant number of patients had severe metabolic acidosis and hyperlactatemia. The organ support used was renal replacement therapy (RRT) (68.6%), vaso-pressors (58.7%) and invasive mechanical ventilation (52.9%). A majority of patients (68.6%) received RRT for toxin removal, renal dysfunction and correction of MALA. Patients with lowest pH and highest serum lactate and metformin levels also had favourable outcomes with use of RRT.

CONCLUSION

Most of the reported cases were on therapeutic doses of metformin but developed toxicity after an acute deterioration in renal functions. These patients may develop severe lactic acidosis, leading to significant morbidity and need for organ support. Despite severe MALA and the need for multiple organ support, they may have good outcomes, especially when RRT is used. The dose of metformin, serum pH, lactate and metformin levels may indicate the severity of toxicity and the need for aggressive therapeutic measures but may not necessarily indicate poor outcomes.

Lactic acid induces fibroblast growth factor 23 (FGF23) production in UMR106 osteoblast-like cells

Endocrine and paracrine fibroblast growth factor 23 (FGF23) is a protein predominantly produced by bone cells with strong impact on phosphate and vitamin D metabolism by targeting the kidney. Plasma FGF23 concentration early rises in kidney and cardiovascular diseases correlating with progression and outcome. Lactic acid is generated in anaerobic glycolysis. Lactic acidosis is the consequence of various physiological and pathological conditions and may be fatal. Since FGF23 production is stimulated by inflammation and lactic acid induces pro-inflammatory signaling, we investigated whether and how lactic acid influences FGF23. Experiments were performed in UMR106 osteoblast-like cells, Fgf23 mRNA levels estimated from quantitative real-time polymerase chain reaction, and FGF23 protein determined by enzyme-linked immunosorbent assay. Lactic acid dose-dependently induced Fgf23 gene expression and up-regulated FGF23 synthesis. Also, Na+-lactate as well as formic acid and acetic acid up-regulated Fgf23. The lactic acid effect was significantly attenuated by nuclear factor kappa-light-chain enhancer of activated B-cells (NFκB) inhibitors wogonin and withaferin A. Lactic acid induces FGF23 production, an effect at least in part mediated by NFκB. Lactic acidosis may, therefore, be paralleled by a surge in plasma FGF23.

The usefulness of measuring the anion gap in diagnosing metformin-associated lactic acidosis: a case series

BACKGROUND

Metformin-associated lactic acidosis (MALA) is a widely documented adverse event of metformin. Despite being considered one of the main causes of metabolic acidosis, the association between an anion gap and MALA diagnosis is still uncertain.

CASE PRESENTATION

Cases involving six Caucasian patients with suspected MALA who were admitted to the emergency department were analysed. All these patients presented with pH values < 7.35, lactate levels > 2 mmol/L, and estimated glomerular filtration < 30 mL/min. Metformin plasma concentrations were > 2.5 mg/L in all the patients. The highest metformin concentrations were not found in the patients with the highest lactate levels. The anion gap values ranged from 12.3 to 39.3, with only two patients exhibiting values > 14.

CONCLUSIONS

In patients with MALA, there is a significant variability in the anion gap values, which is not related to the level of metformin accumulation, and therefore, it is doubtful whether measuring anion gaps is useful as an approach for MALA diagnosis.

Osmolar-gap in the setting of metformin-associated lactic acidosis: Case report and a literature review highlighting an apparently unusual association

RATIONALE

Metformin-associated lactic acidosis (MALA) is a rare adverse effect that has significant morbidity and mortality. MALA is a high anion gap (AG), nonosmolar acidosis. Associated osmolar-gap (OG) is rarely reported, so finding an OG may make the diagnosis of MALA challenging.

PATIENT CONCERNS

Forty-five years' old type II diabetic patient on metformin presented to emergency with a two-day history of vomiting, watery diarrhea, and mild abdominal discomfort. On examinations, he looked dehydrated. Investigation revealed acute kidney injury (AKI) with a high lactic acid (LA) level of 24 mmol/L, pH of 6.8, AG of 40, and an OG of 20 mOsm/kg DIAGNOSES:: The presence of an OG made the diagnosis challenging; the history was negative for alcohol, osmolar substance, or illicit drug ingestion or use. The toxicology screen was negative. After ruling out plausible causes of AG and OG, MALA was deemed the likely reason for his presentation likely precipitated by dehydration and AKI.

INTERVENTIONS

He underwent two sessions of hemodialysis, afterward managed with fluid hydration.

OUTCOMES

On day 3, he was in the polyuric phase suggestive of acute tubular necrosis. His serum creatinine improved afterward with improved acidosis; after 8 days, he was discharged in stable condition.

LESSONS

MALA is a rare side effect of metformin therapy. Acute kidney injury is a known precipitant of MALA. In our review, we highlight the association of MALA and the presence of an OG. We believe that treating physicians should be aware of this relationship to avoid delaying or overlooking such an important diagnosis.

Mortality and renal prognosis in isolated metformin-associated lactic acidosis treated with continuous renal replacement therapy and citrate-calcium-anticoagulation

INTRODUCTION

Use of metformin increases plasma lactate concentration and may lead to metformin-associated lactic acidosis (MALA). Previous studies have suggested severe MALA to have a mortality of 17%-21%, but have included patients with other coincident conditions such as sepsis. The treatment of choice is continuous renal replacement therapy (CRRT), which has been performed using heparin analogues or no anticoagulation in former studies.

MATERIALS AND METHODS

Patients admitted to the Intensive Care Unit of Turku University Hospital Finland with lactic acidosis without any other recognizable etiology than concomitant metformin treatment who required CRRT between years 2010 and 2019 were included. CRRT was performed using regional citrate-calcium-anticoagulation. Data extracted included patient demographics, comorbidities, and clinical parameters at 6-hour intervals about 72 hours from admission. Creatinine and estimated glomerular filtration rate (eGFR) were measured at 1 year after MALA.

RESULTS

A total of 23 patients with isolated MALA were included in the study. Median (IQR) pH was 6.88 (6.81-7.07) and lactate 16.1 (11.9-23.0) mmol/L on admission. Median (IQR) duration of CRRT was 62 (41-70) hours. Seven patients (30%) required mechanical ventilation with a mean duration of 6.0 ± 3.0 days. 90-day mortality was 4.3% and 1-year mortality 13.0%. Creatinine (P = .02) and eGFR (P = .03) remained significantly altered at 1 year of follow-up compared to baseline.

CONCLUSIONS

MALA can be treated effectively and safely with CRRT and citrate-calcium-anticoagulation, usually required for 2-3 days. Mortality of patients with MALA treated with CRRT is low when other conditions inducing lactic acidosis are excluded. MALA episode may be associated with long-lasting kidney injury.

[Lactic Acidosis and Other Misunderstandings]

Lactic Acidosis and Other Misunderstandings Abstract. Lactic acidosis is a frequently encountered clinical problem in intensive care medicine. Nevertheless, many of the underlying biochemical processes are insufficiently understood, which leads to various misconceptions. Physiologically, lactate is an important, continuously produced carrier of energy and by no means a metabolic 'waste product'. Lactate is the corresponding base to lactic acid and is produced directly from pyruvate. In this reaction H⁺ is consumed and therefore lactate production itself cannot be directly responsible for the simultaneously arising acidosis. An elevated lactate level allows no conclusions about the underlying pathophysiological process, and, more importantly, it is not an appropriate marker for tissue oxygenation.

Perioperative Management of Oral Glucose-lowering Drugs in the Patient with Type 2 Diabetes

The right management of oral glucose-lowering drugs aims to identify, assess, and follow patients with diabetes and avoid unnecessary interruptions of the chronic treatment.

Metformin: the updated protective property in kidney disease

Metformin is a frontline hypoglycemic agent, which is mainly prescribed to manage type 2 diabetes mellitus with obesity. Emerging evidence suggests that metformin also exerts protective effects against various kidney diseases. Some postulate that kidney disease is actually a metabolic disease, accompanied by nonresolving pathophysiologic pathways controlling oxidative stress, endoplasmic reticulum stress, inflammation, lipotoxicity, fibrosis, and senescence, as well as insufficient host defense mechanisms such as AMP-activated protein kinase (AMPK) signaling and autophagy. Metformin may interfere with these pathways by orchestrating AMPK signaling and AMPK-independent pathways to protect the kidneys from injury. Furthermore, the United States Food and Drug Administration declared metformin is safe for patients with mild or moderate kidney impairment in 2016, assuaging some conservative attitudes about metformin management in patients with renal insufficiency and broadening the scope of research on the renal protective effects of metformin. This review focuses on the molecular mechanisms by which metformin imparts renal protection and its potential in the treatment of various kidney diseases.

Synthesis and evaluation of novel peptidomimetics bearing p-aminobenzoic acid moiety as potential antidiabetic agents

Aim: Search for a new class of potential antidiabetic agents. Methodology: A series of novel peptidomimetics bearing the p-aminobenzoic acid moiety (TM3-TM6) were designed and synthesized. For all synthetic target molecules, the peroxisome proliferator response element (PPRE) activated activities have been evaluated and the toxicity were computed. Results & discussion: 46 new p-aminobenzoic acid derivatives have been characterized by ¹H NMR, ¹³C NMR and high-resolution mass spectrometry (HRMS). The results of in vitro PPRE-activated activity, molecular docking study and toxicity prediction revealed that these compounds had potential antidiabetic activities and low toxicity. In particular compound 3b had up to 87% PPRE-activated activity compared with pioglitazone. This discovery may provide new insights for finding novel PPRE lead compound.

Is the use of metformin in patients undergoing dialysis hazardous for life? A systematic review of the safety of metformin in patients undergoing dialysis

AIMS

Metformin may have clinical benefits in dialysis patients; however, its safety in this population is unknown. This systematic review evaluated the safety of metformin in dialysis patients.

METHODS

MEDLINE, Embase, CENTRAL, PsycINFO and the Cochrane Library were searched for randomised controlled trials and observational studies evaluating metformin use in dialysis patients. Three authors reviewed the studies and extracted data. The primary outcomes were mortality, occurrence of lactic acidosis and myocardial infarction (MI) in patients taking metformin during dialysis treatment for ≥12 months (long term). Risk of bias was assessed using Risk Of Bias In Nonrandomised Studies of Interventions (ROBINS-1). Overall quality of evidence was assessed using Grading of Recommendations Assessment, Development and Evaluation (GRADE).

RESULTS

Fifteen observational studies were eligible; 7 were prospective observational studies and 8 were case reports/case series. No randomised controlled trials were identified. The 7 prospective observational studies (n = 194) reported on cautious metformin use in patients undergoing maintenance dialysis. Only 3 provided long-term follow-up data. In 2 long-term studies of metformin therapy (≤1000 mg/d) in patients undergoing peritoneal dialysis (PD), 1 reported 6 deaths (6/83; 7%) due to major cardiovascular events (3 MI) and the other reported no deaths (0/35). One long-term study of metformin therapy (250 mg to 500 mg thrice weekly) in patients undergoing haemodialysis reported 4 deaths (4/61; 7%) due to major cardiovascular events (2 MI). These findings provide very low-quality evidence as they come from small observational studies.

CONCLUSION

The evidence regarding the safety of metformin in people undergoing dialysis is inconclusive. Appropriately designed randomised controlled trials are needed to resolve this uncertainty.

Incidence and risk factors for hyperlactatemia in ED patients with acute metformin overdose

INTRODUCTION

The goals of this study are to describe clinical characteristics and risk factors for metabolic acidosis with hyperlactatemia in emergency department (ED) patients with acute metformin overdose.

METHODS

This was a secondary analysis of data from a retrospective observational cohort of adult ED patients presenting with acute drug overdose at two tertiary care hospitals over 5 years. The primary outcomes were: (1) hyperlactatemia, defined as a lactate concentration ≥ 2 mmol/L at any point during hospital admission and, (2) metformin associated lactic acidosis (MALA), defined as a lactate concentration ≥ 5 mmol/L and pH <7.35 at any point during hospital admission.

RESULTS

We screened 3739 acute overdoses; 2872 met eligibility, 56 self-reported metformin overdose (57% female, mean age 55.8). Of these, 39 had measured lactate values. There was a high incidence of hyperlactatemia (56.4%); MALA was less frequent (17.9%). There were no deaths. Low serum bicarbonate was an independent clinical risk factor for hyperlactatemia (adjusted p < 0.05). Acetaminophen co-exposure was an independent clinical risk factor for MALA (OR 24.40, 95% CI 1.6-376.4).

CONCLUSIONS

In ED patients with acute metformin overdose, initial hyperlactatemia is common but MALA is unusual. Acetaminophen co-exposure is a novel independent risk factor for the occurrence of MALA that deserves further investigation.

Effect of high-flow high-volume-intermittent hemodiafiltration on metformin-associated lactic acidosis with circulatory failure: a case report

Background

Metformin-associated lactic acidosis is a well-known life-threatening complication of metformin. We here report the case of a patient who developed metformin-associated lactic acidosis without organ manifestations, due to the simultaneous ingestion of an overdose of metformin and alcohol, and who recovered with high-flow high-volume intermittent hemodiafiltration.

Case presentation

A 44-year-old Asian woman with type 2 diabetes attempted suicide by ingesting 10 tablets of metformin 500 mg and drinking approximately 600 mL of Japanese sake containing 15% alcohol. She was transferred to our emergency department because of disturbed consciousness. Continuous intravenous administration of noradrenalin (0.13 μg/kg per minute) was given because she was in shock. Laboratory findings included a lactate level of 119 mg/dL (13.2 mmol/L), bicarbonate of 14.5 mmol/L, and serum metformin concentration of 1138 ng/mL. She was diagnosed as having metformin-associated lactic acidosis worsened by alcohol. After 4560 mL of bicarbonate ringer (Na⁺ 135 mEq/L, K⁺ 4 mEq/L, Cl⁻ 113 mEq/L, HCO₃⁻ 25 mEq/L) was administered, high-flow high-volume intermittent hemodiafiltration.

(dialysate flow rate: 500 mL/min, substitution flow rate: 3.6 L/h) was carried out for 6 h to treat metabolic acidosis and remove lactic acid and metformin. Consequently, serum metformin concentration decreased to 136 ng/mL and noradrenalin administration became unnecessary to maintain normal vital signs. On hospital day 12, she was moved to the psychiatry ward.

Conclusions

HFHV-iHDF may be able to remove metformin and lactic acid efficiently and may improve the condition of hemodynamically unstable patients with metformin-associated lactic acidosis.

Antidiabetics' usage in type 2 diabetes mellitus: Are prescribing guidelines adhered to? A single centre study

AIM

The primary aim of this study was to examine the prescribing patterns of antidiabetic agents (AA) in this hospital according to current prescribing contraindications (PCI). The secondary aims are to assess factors affecting the prescribing of AA and to evaluate the pharmacist impact on their prescribing.

METHOD

A retrospective cross sectional study was performed to review all prescribed AA over a 3 month period. Data extracted from medical records included: patients' demographics, management and pharmacists' interventions. Appropriateness of prescribing was determined according to the AA prescribing information of the Medical Index of Medical Specialities (MIMS).

RESULTS

A total of 314 AA were examined, of which 74(23%) orders were prescribed despite contraindications. Metformin was the AA to have the most PCI in dosage adjustments in renal impairment (RI). Logistic regression analysis showed patients with severe RI were less likely to be prescribed metformin (OR = 0.115 95%CI(0.048-0.274) P < 0.01), instead insulin was preferred (OR = 2.210 95%CI (1.028-4.751) P < 0.05). Insulin was also more likely to be prescribed in patients with hypertension and hyperglycaemia (OR=2.005 95%CI(1.005-4.001) P < 0.05, OR = 3.535 95%CI(1.756-7.113) P < 0.01) respectively. Sulphonylureas were less likely to be prescribed in patients with cardiovascular disease (OR = 0.339 95%CI(0.163-0.708), P < 0.01. There was low PCI in the other AA. Pharmacists reviewed 89% of AA. PCI was lower in this group compared to those with no pharmacist input (23% vs 28%).

CONCLUSION

The audit showed good adherence to PCI. Pharmacist involvement has a positive impact on AP. Prescriber education is required in relation to dosage adjustments of AA in RI.

Recurrent lactic acidosis and hypoglycemia with inadvertent metformin use: a case of look-alike pills

Metformin is recommended as the first-line agent for the treatment of type 2 diabetes. Although this drug has a generally good safety profile, rare but potentially serious adverse effects may occur. Metformin-associated lactic acidosis, although very uncommon, carries a significant risk of mortality. The relationship between metformin accumulation and lactic acidosis is complex and is affected by the presence of comorbid conditions such as renal and hepatic disease. Plasma metformin levels do not reliably correlate with the severity of lactic acidosis. We present a case of inadvertent metformin overdose in a patient with both renal failure and hepatic cirrhosis, leading to two episodes of lactic acidosis and hypoglycemia. The patient was successfully treated with hemodialysis both times and did not develop any further lactic acidosis or hypoglycemia, after the identification of metformin tablets accidentally mixed in with his supply of sevelamer tablets. Early initiation of renal replacement therapy is key in decreasing lactic acidosis-associated mortality.

LEARNING POINTS

When a toxic ingestion is suspected, direct visualization of the patient's pills is advised in order to rule out the possibility of patient- or pharmacist-related medication errors.Though sending a specimen for determination of the plasma metformin concentration is important when a metformin-treated patient with diabetes presents with lactic acidosis, complex relationships exist between metformin accumulation, hyperlactatemia and acidosis, and the drug may not always be the precipitating factor.Intermittent hemodialysis is recommended as the first-line treatment for metformin-associated lactic acidosis (MALA).An investigational delayed-release form of metformin with reduced systemic absorption may carry a lower risk for MALA in patients with renal insufficiency, in whom metformin therapy may presently be contraindicated.

Hypoglycemia and severe lactic acidosis in a dog following metformin exposure

Hypoglycemia and lactic acidosis are rare complications with metformin use in humans. As metformin is not commonly used in veterinary medicine, severe adverse effects secondary to exposure are not known. Awareness of potentially life-threatening complications with metformin exposure is an important addition to the veterinary literature.

Metformin-associated lactic acidosis (MALA): Moving towards a new paradigm

Although metformin has been used for over 60 years, the balance between the drug's beneficial and adverse effects is still subject to debate. Following an analysis of how cases of so-called "metformin-associated lactic acidosis" (MALA) are reported in the literature, the present article reviews the pitfalls to be avoided when assessing the purported association between metformin and lactic acidosis. By starting from pathophysiological considerations, we propose a new paradigm for lactic acidosis in metformin-treated patients. Metformin therapy does not necessarily induce metformin accumulation, just as metformin accumulation does not necessarily induce hyperlactatemia, and hyperlactatemia does not necessarily induce lactic acidosis. In contrast to the conventional view, MALA probably accounts for a smaller proportion of cases than either metformin-unrelated lactic acidosis or metformin-induced lactic acidosis. Lastly, this review highlights the need for substantial improvements in the reporting of cases of lactic acidosis in metformin-treated patients. Accordingly, we propose a check-list as a guide to clinical practice.

Serum lactate level and mortality in metformin-associated lactic acidosis requiring renal replacement therapy: a systematic review of case reports and case series

Background

The current practice concerning timing, mode, and dose of renal replacement therapy (RRT) in patients with metformin-associated lactic acidosis (MALA) with renal failure remains unknown. To investigate whether serum lactate level and prescription pattern of RRT are associated with mortality in patients with MALA requiring RRT.

Methods

We searched PubMed/Medline and EMBASE from inception to Sep 2014 and applied predetermined exclusion criteria. Case-level data including case’s demographics and clinical information related to MALA were abstracted. Multiple logistic regression modeling was used to examine the predictors of mortality.

Results

A total of 253 unique cases were identified with cumulative mortality of 17.2%. Eighty-seven percent of patients had acute kidney injury. Serum lactate level was significantly higher in non-survivors (median 22.5 mmol/L) than in survivors (17.0 mmol/L, p-value <0.01) and so did the median blood metformin concentrations (58.5 vs. 43.9 mg/L, p-value = 0.05). The survival advantage was not significantly different between the modalities of RRT. The adjusted odds ratio of mortality for every one mmol/L increase in serum lactate level was 1.09 (95% CI 1.02–1.17, p-value = 0.01). The dose-response curve indicated a lactate threshold greater than 20 mmol/L was significantly associated with mortality.

Conclusions

Our study suggests that predialysis level of serum lactate level is an important marker of mortality in MALA patients requiring RRT with a linear dose-response relationship. To better evaluate the optimal prescription of RRT in MALA, we recommend fostering an international consortium to support prospective research and large-scale standardized case collection.

Electronic supplementary material

The online version of this article (doi:10.1186/s12882-017-0640-4) contains supplementary material, which is available to authorized users.

Changes in metformin use in chronic kidney disease

Metformin is one of the oldest and most widely prescribed antidiabetic medicines worldwide. It is the only such medicine that has shown a reduction of cardiovascular mortality in diabetes mellitus type 2. Since many diabetic patients have chronic kidney disease, its use is often curtailed by practitioners due to fear of lactic acidosis and the US Food and Drug Administration (FDA) warnings that, until recently, had been in place for decades. Current guidelines, though somewhat vague regarding dosages, clearly pave the way for spreading the use of metformin in patients with lower glomerular filtration rates. These guidelines also suggest moving away from just looking at serum creatinine to create a cut-off. Metformin’s costs are lower, and in many underdeveloped countries this is the only medicine available for poor patients. More widespread use of metformin will further help with health care costs, as well as obesity. It will simplify the use of diabetes mellitus type 2 management with lower incidences of hypoglycemia. With all the mounting evidence, the FDA is finally requiring labeling changes regarding recommendations, to allow the use of metformin in patients with much reduced kidney function.

The antidiabetic drug metformin decreases mitochondrial respiration and tricarboxylic acid cycle activity in cultured primary rat astrocytes

Metformin is an antidiabetic drug that is used daily by millions of patients worldwide. Metformin is able to cross the blood-brain barrier and has recently been shown to increase glucose consumption and lactate release in cultured astrocytes. However, potential effects of metformin on mitochondrial tricarboxylic acid (TCA) cycle metabolism in astrocytes are unknown. We investigated this by mapping ¹³ C labeling in TCA cycle intermediates and corresponding amino acids after incubation of primary rat astrocytes with [U-¹³ C]glucose. The presence of metformin did not compromise the viability of cultured astrocytes during 4 hr of incubation, but almost doubled cellular glucose consumption and lactate release. Compared with control cells, the presence of metformin dramatically lowered the molecular ¹³ C carbon labeling (MCL) of the cellular TCA cycle intermediates citrate, α-ketoglutarate, succinate, fumarate, and malate, as well as the MCL of the TCA cycle intermediate-derived amino acids glutamate, glutamine, and aspartate. In addition to the total molecular ¹³ C labeling, analysis of the individual isotopomers of TCA cycle intermediates confirmed a severe decline in labeling and a significant lowering in TCA cycling ratio in metformin-treated astrocytes. Finally, the oxygen consumption of mitochondria isolated from metformin-treated astrocytes was drastically reduced in the presence of complex I substrates, but not of complex II substrates. These data demonstrate that exposure to metformin strongly impairs complex I-mediated mitochondrial respiration in astrocytes, which is likely to cause the observed decrease in labeling of mitochondrial TCA cycle intermediates and the stimulation of glycolytic lactate production. © 2017 Wiley Periodicals, Inc.

Metformin: From Research to Clinical Practice

Metformin is the recommended first-line oral glucose-lowering drug initiated to control hyperglycemia in type 2 diabetes mellitus. It acts in the liver, small intestines, and skeletal muscles with its major effect on decreasing hepatic gluconeogenesis. It is safe, inexpensive, and weight neutral and can be associated with weight loss. It can reduce microvascular complication risk and its use is associated with a lower cardiovascular mortality compared with sulfonylurea therapy. It is also used to delay the onset of type 2 diabetes mellitus, in treating gestational diabetes, and in women with polycystic ovary syndrome.

Lactic acidosis and the relationship with metformin usage: Case reports

AIMS

The principal objective of this study was to retrospectively review a series of cases of lactic acidosis (LA) in patients with type 2 diabetes mellitus (T2DM) and examine the relationship with the use of metformin. More generally, the study enabled an investigation of the profiles of patients diagnosed with LA and clinical variables associated with in-hospital mortality.

METHODS

All patients admitted to the Royal Hobart Hospital in Tasmania with LA (lactate >5.0 mmol/L and pH <7.35) over a 4-year period were included. Data extracted included patient demographics, medical history, medications, acute and chronic conditions associated with LA, and relevant pathology results. Multivariate logistic regression analysis was used to identify predictors for in-hospital mortality in patients with LA.

RESULTS

A total of 139 patients with LA were included in this study. Of these, 23 patients had T2DM and 11 patients were taking metformin. All metformin-treated patients had at least 1 additional medical condition (either chronic or acute) associated with an increased risk for LA. More than half (n = 72, 51.8%) of the patients with LA died during hospitalization. Multivariate logistic regression revealed older age and lower pH as the significant independent predictors (P < 0.05) for in-hospital mortality.

CONCLUSION

LA was associated with high in-hospital mortality, with older age and lower pH as the significant risk factors for mortality. In patients with LA, approximately half of the patients with T2DM were receiving metformin. All the patients treated with metformin had other medical conditions that were risk factors for developing LA. The role of LA in patients treated with metformin is seemingly overemphasized.

Polytherapy and the risk of potentially inappropriate prescriptions (PIPs) among elderly and very elderly patients in three different settings (hospital, community, long-term care facilities) of the Friuli Venezia Giulia region, Italy: are the very elderly at higher risk of PIPs?

PURPOSE

The aim of this point-prevalence study was to assess the occurrence of polypharmacy and hyperpolypharmacy and the risk of potentially inappropriate prescriptions (PIPs) among elderly and very elderly patients in different health-care settings of the Friuli-Venezia Giulia region in the North-East of Italy.

METHODS

Prescription pattern of elderly (65-79 years) and very elderly (>79 years) patients in three different health-care settings [hospitals, general practitioners, and long-term care facilities (LTCFs)] was assessed in March 2014, and PIPs were assessed according to the Beers criteria. Other situations at potentially high risk were checked.

RESULTS

A total of 1582 patients (hospital, n = 528; outpatients, n = 527; nursing homes, n = 527) were included. Very elderly were more represented in hospitals (60.4%) and LTCFs (77.1%) than among general practitioners (37.6%). Polypharmacy and hyperpolypharmacy rates ranged 57.7-73.7% and 9.7-15.6%, respectively. The most frequently prescribed drugs were the proton pump inhibitors, whereas the most common PIPs resulted the benzodiazepines. Multinomial regression analysis showed that female sex, age > 79 years, hyperpolypharmacy, and chronic kidney disease were associated with the risk of having ≥2 PIPs. Two situations at high risk of PIPs not contemplated by the Beers criteria were recurrent in the study population and concerned the statins and metformin.

CONCLUSIONS

Polypharmacy and hyperpolypharmacy among elderly and very elderly are strictly associated with the risk of multiple PIPs. The findings offer the opportunity to remark that improvement of the knowledge of safe drug use is generally needed in aging societies and may become of utmost relevance among health-care workers operating in LTCFs. Copyright © 2016 John Wiley & Sons, Ltd.

Skeletal muscle lactate overproduction during metformin intoxication: An animal study with reverse microdialysis

Lactic acidosis during metformin intoxication is classically mainly attributed to diminished lactate clearance through liver gluconeogenesis. Here we studied 6 healthy, sedated and mechanically ventilated pigs to clarify whether high dose of metformin also increases skeletal muscle lactate production. Each animal had two microdialysis catheters inserted in gluteus muscles, one per side. One catheter was infused with saline (control) while the other one was infused with metformin diluted in saline (1M), both at a rate of 0.3μl/min. Dialysate lactate concentration and lactate-to-pyruvate ratio, a marker of the balance between anaerobic glycolysis and aerobic (mitochondrial) metabolism, were measured every 3h, for 12h. Continuous infusion of metformin caused a progressive rise in dialysate lactate level (p=0.007) and lactate-to-pyruvate ratio (p<0.001) compared to that of saline, as for mitochondrial "poisoning". These findings suggest that skeletal muscle lactate overproduction contributes to the development of metformin-induced lactic acidosis.

Metformin associated lactic acidosis (MALA): clinical profiling and management

Metformin (MF) accumulation during acute kidney injury is associated with high anion gap lactic acidosis type B (MF-associated lactic acidosis, MALA), a serious medical condition leading to high mortality. Despite dose adjustment for renal failure, diabetic patients with chronic kidney disease (CKD) stage III-IV are at risk for rapid decline in renal function by whatever reason, so that MF toxicity might arise if the drug is not timely withdrawn. Sixteen consecutive patients were admitted to our Hospital's Emergency Department with clinical findings consistent with MALA. Fifteen had prior history of CKD, 60 % of them with GFR between 30 and 60 ml/min. Of these, 5 required mechanical ventilation and cardiovascular support; 3 promptly recovered renal function after rehydration, whereas 10 (62 %) required continuous veno-venous renal replacement treatment. SOFA and SAPS II scores were significantly related to the degree of lactic acidosis. In addition, lactate levels were relevant to therapeutic choices, since they were higher in dialyzed patients than in those on conservative treatment (11.92 mmol/l vs 5.7 mmol/l, p = 0.03). The overall death rate has been 31 %, with poorer prognosis for worse acidemia, as serum pH was significantly lower in non-survivors (pH 6.96 vs 7.16, p > 0.04). Our own data and a review of the literature suggest that aged, hemodynamically frail patients, with several comorbidities and CKD, are at greater risk of MALA, despite MF dosage adjustment. Moreover, renal replacement therapy rather than simple acidosis correction by administration of alkali seems the treatment of choice, based on eventual renal recovery and overall outcome.

Drug-Induced Metabolic Acidosis

Metabolic acidosis could emerge from diseases disrupting acid-base equilibrium or from drugs that induce similar derangements. Occurrences are usually accompanied by comorbid conditions of drug-induced metabolic acidosis, and clinical outcomes may range from mild to fatal. It is imperative that clinicians not only are fully aware of the list of drugs that may lead to metabolic acidosis but also understand the underlying pathogenic mechanisms. In this review, we categorized drug-induced metabolic acidosis in terms of pathophysiological mechanisms, as well as individual drugs’ characteristics.

Adverse event notifications implicating metformin with lactic acidosis in Australia

OBJECTIVE

To summarise the reported lactic acidosis cases associated with metformin from the Australian Therapeutic Goods Administration (TGA) and estimate the incidence of metformin-associated lactic acidosis (MALA) in Australia.

METHOD

All "lactic acidosis" cases associated with metformin and reported to the TGA between January 1971 and October 2014 were included. Data extracted included patient demographics, medical history and co-existing conditions, metformin dosage and relevant pathology results.

RESULT

A total of 152 cases of suspected MALA were included in this study. For 20 patients the outcome was unknown. There were 23 patients (n=132, 17.4%) reported as deceased. Plasma lactate levels were higher in non-survivors (p=0.02). Thirty-five patients (n=132, 26.5%) were reported to have at least one pre-existing contraindication to the use of metformin; this proportion was not different between patients who died or survived. Renal impairment was the most common contraindication. Approximately 75% of patients were reported to have at least one clinical condition which might cause acidosis. Metformin dosage, plasma lactate and serum creatinine were not correlated. Based on the cases reported to the TGA, the incidence of MALA in Australia was estimated to be 2.3 (95% CI, 1.5-3.1) cases per 100,000 patient-years between 1997 and 2011.

CONCLUSION

Pre-existing clinical conditions, such as renal impairment, and acute illnesses associated with lactic acidosis were frequently reported in the cases of MALA. The estimated incidence of MALA was lower than in most previous studies in other countries, probably due to the nature of spontaneous reports to the TGA.

The Antidiabetic Drug Metformin Stimulates Glycolytic Lactate Production in Cultured Primary Rat Astrocytes

Metformin is the most frequently used drug for the treatment of type 2 diabetes in humans. However, only little is known about effects of metformin on brain metabolism. To investigate potential metabolic consequences of an exposure of brain cells to metformin, we incubated rat astrocyte-rich primary cultures with this compound. Metformin in concentrations of up to 30 mM did not acutely compromise the viability of astrocytes, but caused a time- and concentration-dependent increase in cellular glucose consumption and lactate production. For acute incubations in the hour range, the presence of 10 mM metformin doubled the glycolytic flux, while already 1 mM metformin doubled glycolytic flux during incubation for 24 h. In addition to metformin, also other guanidino compounds increased astrocytic lactate production. After 4 h of incubation, half-maximal stimulation of glycolysis was observed for metformin, guanidine and phenformin at concentrations of around 3 mM, 3 mM and 30 µM, respectively. The acute stimulation of glycolytic lactate production by metformin was persistent after removal of extracellular metformin and was also observed, if glucose was absent from the incubation medium or replaced by other hexoses. The metformin-induced stimulation of glycolytic flux was not prevented by compound C, an inhibitor of AMP-dependent protein kinase, nor was it additive to the stimulation of glycolytic flux caused by respiratory chain inhibitors. These data demonstrate that the antidiabetic drug metformin has the potential to strongly activate glycolytic lactate production in brain astrocytes.

Extracorporeal Treatment for Metformin Poisoning: Systematic Review and Recommendations From the Extracorporeal Treatments in Poisoning Workgroup

BACKGROUND

Metformin toxicity, a challenging clinical entity, is associated with a mortality of 30%. The role of extracorporeal treatments such as hemodialysis is poorly defined at present. Here, the Extracorporeal Treatments In Poisoning workgroup, comprising international experts representing diverse professions, presents its systematic review and clinical recommendations for extracorporeal treatment in metformin poisoning.

METHODS

A systematic literature search was performed, data extracted, findings summarized, and structured voting statements developed. A two-round modified Delphi method was used to achieve consensus on voting statements and RAND/UCLA Appropriateness Method to quantify disagreement. Anonymized votes and opinions were compiled and discussed. A second vote determined the final recommendations.

RESULTS

One hundred seventy-five articles were identified, including 63 deaths: one observational study, 160 case reports or series, 11 studies of descriptive cohorts, and three pharmacokinetic studies in end-stage renal disease, yielding a very low quality of evidence for all recommendations. The workgroup concluded that metformin is moderately dialyzable (level of evidence C) and made the following recommendations: extracorporeal treatment is recommended in severe metformin poisoning (1D). Indications for extracorporeal treatment include lactate concentration greater than 20 mmol/L (1D), pH less than or equal to 7.0 (1D), shock (1D), failure of standard supportive measures (1D), and decreased level of consciousness (2D). Extracorporeal treatment should be continued until the lactate concentration is less than 3 mmol/L (1D) and pH greater than 7.35 (1D), at which time close monitoring is warranted to determine the need for additional courses of extracorporeal treatment. Intermittent hemodialysis is preferred initially (1D), but continuous renal replacement therapies may be considered if hemodialysis is unavailable (2D). Repeat extracorporeal treatment sessions may use hemodialysis (1D) or continuous renal replacement therapy (1D).

CONCLUSION

Metformin poisoning with lactic acidosis appears to be amenable to extracorporeal treatments. Despite clinical evidence comprised mostly of case reports and suboptimal toxicokinetic data, the workgroup recommended extracorporeal removal in the case of severe metformin poisoning.

Lactic Acidosis in a Patient with Type 2 Diabetes Mellitus

Lactic acidosis occurs when lactate production exceeds its metabolism. There are many possible causes of lactic acidosis, and in any given patient, several causes may coexist. This Attending Rounds presents a case in point. Metformin's role in the pathogenesis of lactic acidosis in patients with diabetes mellitus is complex, as the present case illustrates. The treatment of lactic acidosis is controversial, except for the imperative to remedy its underlying cause. The use of sodium bicarbonate to treat the often alarming metabolic derangements may be quite efficacious in that regard but is of questionable benefit to patients. Renal replacement therapies (RRTs) have particular appeal in this setting for a variety of reasons, but their effect on clinical outcomes is untested.

Hemodynamic consequences of severe lactic acidosis in shock states: from bench to bedside

Lactic acidosis is a very common biological issue for shock patients. Experimental data clearly demonstrate that metabolic acidosis, including lactic acidosis, participates in the reduction of cardiac contractility and in the vascular hyporesponsiveness to vasopressors through various mechanisms. However, the contributions of each mechanism responsible for these deleterious effects have not been fully determined and their respective consequences on organ failure are still poorly defined, particularly in humans. Despite some convincing experimental data, no clinical trial has established the level at which pH becomes deleterious for hemodynamics. Consequently, the essential treatment for lactic acidosis in shock patients is to correct the cause. It is unknown, however, whether symptomatic pH correction is beneficial in shock patients. The latest Surviving Sepsis Campaign guidelines recommend against the use of buffer therapy with pH ≥7.15 and issue no recommendation for pH levels <7.15. Furthermore, based on strong experimental and clinical evidence, sodium bicarbonate infusion alone is not recommended for restoring pH. Indeed, bicarbonate induces carbon dioxide generation and hypocalcemia, both cardiovascular depressant factors. This review addresses the principal hemodynamic consequences of shock-associated lactic acidosis. Despite the lack of formal evidence, this review also highlights the various adapted supportive therapy options that could be putatively added to causal treatment in attempting to reverse the hemodynamic consequences of shock-associated lactic acidosis.

Antidiabetic therapy in post kidney transplantation diabetes mellitus

Post-transplantation diabetes mellitus (PTDM) is a common complication after kidney transplantation that affects up to 40% of kidney transplant recipients. By pathogenesis, PTDM is a diabetes form of its own, and may be characterised by a sudden, drug-induced deficiency in insulin secretion rather than worsening of insulin resistance over time. In the context of deteriorating allograft function leading to a re-occurrence of chronic kidney disease after transplantation, pharmacological interventions in PTDM patients deserve special attention. In the present review, we aim at presenting the current evidence regarding efficacy and safety of the modern antidiabetic armamentarium. Specifically, we focus on incretin-based therapies and insulin treatment, besides metformin and glitazones, and discuss their respective advantages and pitfalls. Although recent pilot trials are available in both prediabetes and PTDM, further studies are warranted to elucidate the ideal timing of various antidiabetics as well as its long-term impact on safety, glucose metabolism and cardiovascular outcomes in kidney transplant recipients.