Management of metformin-associated lactic acidosis by continuous renal replacement therapy

Metformin Toxicity Leading to Severe Refractory Hyperkalemia and Metabolic Acidosis: A Case Report

Metformin is a widely prescribed, oral, anti-diabetic agent for the treatment of type 2 diabetes mellitus (DM2). While generally well-tolerated, metformin can accumulate in patients with acute kidney injury (AKI) or chronic kidney disease (CKD), leading to potentially life-threatening complications such as metformin-associated lactic acidosis (MALA). Severe hyperkalemia is a rare but serious manifestation of metformin toxicity. We report a case of a 74-year-old African American man with DM2, hypertension, and CKD stage 3a, who presented with nausea, vomiting, lethargy, and diarrhea. Laboratory findings revealed severe AKI with a creatinine level of 8 mg/dL (baseline 1.7 mg/dL) and a potassium level of 7.8 mEq/L. The patient developed refractory hyperkalemia requiring multiple interventions and eventually continuous renal replacement therapy. Further evaluation revealed metformin-induced severe lactic acidosis with a metformin level of 21 mcg/mL (therapeutic range <5 mcg/mL). This case highlights the importance of recognizing metformin toxicity as a potential cause of severe, refractory hyperkalemia and metabolic acidosis in patients with AKI or CKD. Early recognition and prompt discontinuation of metformin, along with appropriate management of electrolyte disturbances and metabolic derangements, are crucial in preventing life-threatening complications.

Calcium-Citrate Anticoagulation during Continuous Renal Replacement Therapy in Patients with Metformin Intoxication: A Case Series, Mathematical Estimation of Citrate Accumulation, and Literature Review

INTRODUCTION

Metformin intoxication causes lactic acidosis by inhibiting Krebs' cycle and oxidative phosphorylation. Continuous renal replacement therapy (CRRT) is recommended for metformin removal in critically ill patients. According to current guidelines, regional citrate anticoagulation (RCA) is the first-line strategy. However, since metformin also inhibits citrate metabolism, a risk of citrate accumulation could be hypothesized. In the present study, we monitored the potential citrate accumulation in metformin-associated lactic acidosis (MALA) patients treated with CRRT and RCA using the physical-chemical approach to acid-base interpretation.

METHODS

We collected a case series of 3 patients with MALA. Patients were treated with continuous venovenous hemofiltration (CVVH), and RCA was performed with diluted citrate solution. Citrate accumulation was monitored through two methods: the ratio between total and ionized plasma calcium concentrations (T/I calcium ratio) above 2.5 and the strong ion gap (SIG) to identify an increased concentration of unmeasured anions. Lastly, a mathematical model was developed to estimate the expected citrate accumulation during CVVH and RCA.

RESULTS

All 3 patients showed a resolution of MALA after the treatment with CVVH. The T/I calcium ratio was consistently below 2.5, and SIG decreased, reaching values lower than 6 mEq/L after 48 h of CVVH treatment. According to the mathematical model, the estimated SIG without citrate metabolism should have been around 21 mEq/L due to citrate accumulation.

CONCLUSIONS

In our clinical management, no signs of citrate accumulation were recorded in MALA patients during treatment with CVVH and RCA. Our data support the safe use of diluted citrate to perform RCA during metformin intoxication.

Combined lactic acidosis and ketoacidosis in a female diabetic patient with severe heart failure

SGLT2i are now recommended in a wide spectrum of indications including type 2 diabetes (T2DM), heart failure, and chronic kidney disease. This medication class is now available in combination with metformin, which is still a fundamental treatment in patients with T2DM. Despite excellent proven safety profile for both drugs, the expanding use of these agents in clinical practice may lead to an increased incidence of rare side effects, like metformin-associated lactic acidosis (MALA) and euglycemic diabetic ketoacidosis (EDKA), which can be life-threatening. A 58-year-old woman with T2DM and severe heart failure treated by metformin and empagliflozin developed progressive EDKA triggered by fasting that was also complicated by severe acute renal failure and MALA. She was successfully treated with intermittent hemodialysis. This case report highlights the importance of the recognition of rare, but very serious adverse effects due to combined metformin and SGLT2i therapy.

Clinical presentation of Warburg effect in aggressive lymphoma: a case report

BACKGROUND

The Warburg effect is a rare condition in tumor biology, illustrated by significant lactate production in the presence of oxygen. The Warburg effect is associated with very poor prognosis in patients with malignancy.

CASE PRESENTATION

We report a 76-year-old Caucasian woman with double-expressor diffuse large B cell lymphoma who presented with severe lactic acidosis and extreme hypoglycemia with normal mentation. Her lactic acidosis was initially controlled with a bicarbonate infusion, and the patient was started promptly on steroids, followed by chemotherapy, but her clinical course was complicated by tumor lysis syndrome, acute renal failure requiring hemodialysis, and progressive liver failure. She manifested a temporary clinical response to chemotherapy but eventually died of complications.

CONCLUSIONS

This case demonstrates the importance of prompt recognition of the Warburg effect, aggressive supportive measures, and early initiation of chemotherapy. Future studies are needed to characterize the role of hemodialysis in this setting.

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.

Unusual Case of Metformin-Associated Lactic Acidosis in Patient with Type 2 Diabetes Mellitus

BACKGROUND Metformin is recommended as the first-line therapy for type 2 diabetes mellitus, according to the American Diabetes Association. It is considered a safe medication with minimal adverse effects, with the most common being gastrointestinal. Metformin-associated lactic acidosis (MALA) is a rare but life-threatening complication. MALA usually occurs in patients with kidney dysfunction. However, it can still occur with preserved kidney function with the ingestion of a large dose of metformin. CASE REPORT A 66-year-old man with a significant medical history of type 2 diabetes mellitus presented after an intentional ingestion of a high dose of metformin (3000 mg/day). He was admitted to our hospital with symptoms of fatigue, nausea, vomiting, abdominal pain, and watery diarrhea lasting for 3 days. His initial laboratory findings were remarkable, with a serum creatinine level of 819 µmol/L. Arterial blood gas revealed severe lactic acidosis, with a pH of 6.94, HCO₃⁻- of 3 mEq/L, anion gap of 48 mmol/L, and lactate level of 15 mmol/L. Emergent continuous renal replacement therapy was done. Two days later, his condition improved considerably, and the lactic acidosis was resolved entirely. He was discharged on day 11 of hospitalization. CONCLUSIONS MALA is rare but life-threatening complication of treatment with metformin. MALA should be considered when there is evidence of metformin ingestion and renal insufficiency in patients with lactic acidosis. The curative treatment of MALA is based on hemodialysis, but the main remedy is prevention, which requires patient compliance with taking metformin as prescribed.

Relationship between metformin use and lactic acidosis in advanced chronic kidney disease: The REMIND-TMU study

BACKGROUND

Evidence of metformin-associated lactic acidosis (MALA) in advanced chronic kidney disease (CKD) has been limited due to high mortality rate but rare incidence rate. The mechanism of increased MALA in advanced CKD is mainly based on the hypothesis of decreased drug elimination, which might also be confounded by increased comorbidities as CKD progresses. The goal of the study is to analyze the incidence and associated factors of lactic acidosis between metformin user and non-user with advanced CKD.

METHODS

This study used a three million population-based, propensity score-matched cohort from 2008 to 2016. The primary outcome was laboratory-defined lactic acidosis. Relationships between the probability of lactic acidosis and various estimated glomerular filtration rate (eGFR) values in advanced CKD patients were also presented in regression analysis.

RESULTS

Adults with type 2 diabetes whose eGFR was <30 mL/min/1.73 m² were enrolled in this study. After the process of propensity score matching, 7707 patients were divided into metformin and non-metformin groups. In linear regression model, metformin significantly increased the risk of lactic acidosis (p=0.0204) as the eGFR declined in advanced CKD over a mean follow up of over 600 days even after confounder adjustment with age, sex and comorbidities.

CONCLUSIONS

Metformin was associated with a significant increased risk of laboratory-defined lactic acidosis (p=0.0204) even after adjusting confounder such as age, sex and underlying comorbidities. This "REMIND" study reminds us that metformin-associated lactic acidosis is mainly caused by decreased drug renal elimination other than underlying comorbidities in advanced CKD patients.

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.

Continuous Renal Replacement Therapy (CRRT) for Nonrenal Indications among Critically Ill Children with Malignancy

The role of continuous renal replacement therapy (CRRT) has been expanding beyond support for acute kidney injury (AKI) in recent years. Children with malignancy are particularly at risk of developing conditions that may require CRRT. We reported three children with malignancy who received CRRT for non-AKI indications. Patient 1 was a 17-year-old teenage girl who developed refractory type B lactic acidosis due to relapse of acute lymphoblastic leukemia (ALL). Her peak lactate level was 18 mmol/L, and the lowest pH and bicarbonate level was 7.13 and 6.0 mmol/L, respectively. She received three sessions of high-volume hemodiafiltration to bring down the lactate level. Patient 2 was a 15-year-old male with T-cell ALL who developed cytokine storm requiring mechanical ventilatory and high-dose inotropic support due to necrotizing enterocolitis complicated by pneumoperitoneum and Klebsiella pneumoniae septicemia. He received two sessions of hemoperfusion using a specific filter capable of endotoxin absorption and cytokine removal and was successfully weaned off all inotropes after the treatment. Patient 3 was an 8-year-old boy who received bone marrow transplantation and developed worsening hyperbilirubinemia and deteriorating liver function. He received a session of single-pass albumin dialysis for bilirubin removal prior to liver biopsy. Except for mild electrolyte disturbances, no major CRRT complication was encountered. Our report demonstrated that CRRT is an effective and safe procedure for a wide spectrum of nonrenal conditions among children with oncological diagnoses in the pediatric intensive care unit. However, the optimal dose, regime, timing of initiation, and monitoring target for these indications remain to be determined.

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.

Metformin-associated lactic acidosis: reinforcing learning points

Metformin-associated lactic acidosis (MALA) carries a high mortality rate. It is seen in patients with type 2 diabetes on metformin or patients who attempt suicide with metformin overdose. We present the case of a man in his early 20s with type 2 diabetes, hypertension and hypothyroidism who presented with agitation, abdominal pain and vomiting after ingesting 50-60 g of metformin; he developed severe lactic acidosis (blood pH 6.93, bicarbonate 7.8 mEq/L, lactate 28.0 mEq/L). He was managed with intravenous 8.4% bicarbonate infusion and continuous venovenous haemodiafiltration. He also developed acute renal failure (ARF) requiring intermittent haemodialysis and continuous haemodiafiltration. MALA is uncommon and causes changes in different vital organs and even death. The primary goals of therapy are restoration of acid-base status and removal of metformin. Early renal replacement therapy for ARF can result in rapid reversal of the acidosis and good recovery, even with levels of lactate normally considered to be incompatible with survival.

The Association between Metformin Therapy and Lactic Acidosis

INTRODUCTION AND OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Do Patients Die with or from Metformin-Associated Lactic Acidosis (MALA)? Systematic Review and Meta-analysis of pH and Lactate as Predictors of Mortality in MALA

OBJECTIVES

Metformin-associated lactic acidosis (MALA) may occur after acute metformin overdose, or from therapeutic use in patients with renal compromise. The mortality is high, historically 50% and more recently 25%. In many disease states, lactate concentration is strongly associated with mortality. The aim of this systematic review and meta-analysis is to investigate the utility of pH and lactate concentration in predicting mortality in patients with MALA.

METHODS

We searched PubMed, EMBASE, and Web of Science from their inception to April 2019 for case reports, case series, prospective, and retrospective studies investigating mortality in patients with MALA. Cases and studies were reviewed by all authors and included if they reported data on pH, lactate, and outcome. Where necessary, authors of studies were contacted for patient-level data. Receiver operating characteristic (ROC) curves were generated for pH and lactate for predicting mortality in patients with MALA.

RESULTS

Forty-four studies were included encompassing 170 cases of MALA with median age of 68.5 years old. Median pH and lactate were 7.02 mmol/L and 14.45 mmol/L, respectively. Overall mortality was 36.2% (95% CI 29.6-43.94). Neither lactate nor pH was a good predictor of mortality among patients with MALA. The area under the ROC curve for lactate and pH were 0.59 (0.51-0.68) and 0.43 (0.34-0.52), respectively.

CONCLUSION

Our review found higher mortality from MALA than seen in recent studies. This may be due to variation in standard medical practice both geographically and across the study interval, sample size, misidentification of MALA for another disease process and vice versa, confounding by selection and reporting biases, and treatment intensity (e.g., hemodialysis) influenced by degree of pH and lactate derangement. The ROC curves showed poor predictive power of either lactate or pH for mortality in MALA. With the exception of patients with acute metformin overdose, patients with MALA usually have coexisting precipitating illnesses such as sepsis or renal failure, though lactate from MALA is generally higher than would be considered survivable for those disease states on their own. It is possible that mortality is more related to that coexisting illness than MALA itself, and many patients die with MALA rather than from MALA. Additional work looking solely at MALA in healthy patients with acute metformin overdose may show a closer relationship between lactate, pH, and mortality.

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.

Metformin-associated lactic acidosis precipitated by liraglutide use: adverse effects of aggressive antihyperglycaemic therapy

In conjunction with BMJ Case Reports, DTB will feature occasional drug-related cases that are likely to be of interest to readers. These will include cases that involve recently marketed drugs for which there is limited knowledge of adverse effects and cases that highlight unusual reactions to drugs that have been marketed for several years.

Metformin-associated lactic acidosis precipitated by liraglutide use: adverse effects of aggressive antihyperglycaemic therapy

Older patients with type 2 diabetes are prone to developing adverse events with aggressive antihyperglycaemic therapy. Metformin-associated lactic acidosis (MALA) is one such rare, life-threatening adverse drug effect. We report the case of a 70-year-old man with a glycated haemoglobin of 7.9% who was on a stable, maximally tolerated dose of metformin for managing his type 2 diabetes. He was initiated on liraglutide injections with hopes to achieve better glycaemic control, but developed unrelenting nausea and vomiting during the third week of treatment. He presented to the hospital with these symptoms and was noted to have severe MALA. He sustained an in-hospital cardiac arrest requiring emergent resuscitation along with vasopressor and mechanical ventilator support. He underwent continuous venovenous haemodiafiltration to remove metformin and correct the acidosis, following which he stabilised and supportive therapy was weaned off. He was discharged from the hospital on insulin therapy with incomplete renal recovery.

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.

Risk of lactic acidosis in type 2 diabetes patients using metformin: A case control study

BACKGROUND

Metformin constitutes first-line treatment of type 2 diabetes mellitus. It is presumed to have lactic acidosis as a dangerous, but rare, side effect.

OBJECTIVES

To estimate the incidence rate of lactic acidosis in patients with type 2 diabetes mellitus as well as to estimate the relative risk of lactic acidosis associated with metformin treatment.

METHODS

This is a population-based combined cohort and case-control study among patients with type 2 diabetes mellitus who were acutely admitted with lactic acidosis at Odense University Hospital, Denmark; in the period from 1st June 2009 to 1st October 2013. The patients included as cases were all acutely hospitalized with lactic acidosis (pH <7.35 and lactate ≥2.0 mmol/l). For each case, we identified 24 age- and sex-matched controls sampled from the same cohort with type 2 diabetes mellitus. The use of metformin identified by using a prescription database. Analyses included multivariable logistic regression and adjusting for predefined confounding: renal function, HbA1c, comorbidity and diabetes duration.

RESULTS

Our cohort included 10,652 patients with type 2 diabetes mellitus with a median age of 74 years, and 51.5% were male. During follow-up, 163 individuals were hospitalized with lactic acidosis, corresponding to an incidence rate of 391/100,000 person years. Use of metformin was not associated with lactic acidosis: adjusted odds ratio was 0.79 (95%CI 0.54-1.17).

CONCLUSION

Among patients with type 2 diabetes mellitus, the incidence rate of acute hospitalization with lactic acidosis was 391/100,000 person years. Use of metformin did not increase the risk of lactic acidosis. However, comorbidity seems to be an important risk factor.

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.

Inhibition of bioenergetic metabolism by the combination of metformin and 2-deoxyglucose highly decreases viability of feline mammary carcinoma cells

Feline mammary carcinoma (FMC) is a highly aggressive pathology that has been proposed as an interesting model of breast cancer disease, especially for the hormone refractory subgroup. Recently, cancer cell metabolism has been described as a hallmark of cancer cells. Here, we investigate the effects and mechanism of metabolic modulation by metformin (MET, anti-diabetic drug), 2-deoxyglucose (2DG, hexokinase inhibitor) or a combination of both drugs, MET/2DG on two established FMC cells lines: AlRB (HER2 (3+) and Ki67<5%) and AlRATN (HER2 (-) and Ki67>15%). We found that treatments significantly decreased both FMC cells viability by up to 80%. AlRB resulted more sensitive to 2DG than AlRATN (IC50: 3.15 vs 6.32mM, respectively). The combination of MET/2DG potentiated the effects of the individually added drugs on FMC cells. In addition, MET/2DG caused an increased in intracellular oxidants, autophagic vesicles and completely inhibited colony formation. Conversely, only MET significantly altered plasma membrane integrity, presented late apoptotic/necrotic cells and increased both glucose consumption and lactate concentration. Our results support further studies to investigate the potential use of this metabolic modulation approach in a clinical veterinary setting.

Metformin-Associated Lactic Acidosis Undergoing Renal Replacement Therapy in Intensive Care Units: A Five-Million Population-Based Study in the North-West of Italy

BACKGROUND

Metformin-associated lactic acidosis (MALA) is a severe complication of drug administration with significant morbidity and mortality. So far no study in large population areas have examined the incidence, clinical profile and outcome of acute kidney injury (AKI)-MALA patients admitted in intensive care units (ICUs) and treated by renal replacement therapy (MALA-RRT).

METHODS

Retrospective analysis over a 6-year period (2010-2015) in Piedmont and Aosta Valley regions (5,305,940 inhabitants, 141,174 diabetics treated with metformin) of all MALA-RRT cases.

RESULTS

One hundred and seventeen cases of AKI-MALA-RRT were observed (12.04/100,000 metformin treated diabetics, 1.45% of all RRT-ICU patients). Survival rate was 78.3%. The average duration of RRT was 4.0 days at mean dialysis effluent of 977 mL/kg/day. At admission most patients were dehydrated, and experienced shock and oliguria.

CONCLUSION

Our data showed that MALA-RRT is a common complication, needing more prevention. Adopted policy of early, extended, continuous and high efficiency dialysis could contribute to an observed high survival rate. Video Journal Club "Cappuccino with Claudio Ronco" at http://www.karger.com/?doi=471917.

A Case of Lactate Containing Peritoneal Dialysis Solution Induced Lactic Acidosis Corrected by Changing to Hemodialysis

Elevated lactate levels are associated with acute illnesses, and the mortality is high. Here, we report a case of lactate-containing peritoneal dialysis (PD) solution inducing lactic acidosis corrected by changing to hemodialysis (HD). This 70-year-old female patient was treated with PD 8 months previously for end-stage renal disease caused by diabetes mellitus. She was admitted complaining of general weakness. Initial lactate level was 22.1 mg/dL and increased to 62.4 mg/dL showing high anion gap metabolic acidosis and compensatory hyperventilation. There are no definite causes of lactic acidosis besides the use of PD solutions containing a lactate component. The patient's lactate level was decreased after temporarily changing the dialysis modality to HD. Her lactate level was increased again after restarting PD, and decreased to normal after restarting HD. We report this case because physicians should consider lactate-containing PD solution as a possible cause of lactic acidosis.

Metformin-associated lactic acidosis treated with continuous renal replacement therapy

Metformin-associated lactic acidosis (MALA) is a rare but life-threatening complication. We report a case of MALA in a man aged 71 years who was treated with continuous renal replacement therapy (CRRT). The patient was brought to the hospital for prolonged and gradual worsening gastrointestinal symptoms. Although he received intravenous treatment, he developed catecholamine-resistant shock, and blood gas analysis revealed lactic acidosis. Bicarbonate and antibiotics for possible sepsis were initiated, but with no clear benefit. Owing to haemodynamic instability with metabolic acidosis, urgent CRRT was given: it was immediately effective in reducing lactate levels; pH values completely normalised within 18 hours, and he was stabilised. MALA sometimes presents with non-specific symptoms, and is important to consider when treating unexplainable metabolic acidosis. In severe cases, CRRT has potential merit, particularly in haemodynamically unstable patients. It is important to be familiar with MALA as a medical emergency, even for emergency physicians.

Can an early diagnostic procedure of metformin-associated lactic acidosis in an emergency unit reduce mortality?

OBJECTIVE

Metformin-associated lactic acidosis (MALA) is a rare but serious adverse reaction with a mortality rate of up to 50%. Unfortunately, diagnosis and care management are often delayed. The objective was to assess the impact on the mortality rate and length of hospital stay of a MALA early diagnosis procedure in diabetic patients with metformin at emergency department (ED) admission.

METHOD

From 1/7/2012, a new MALA diagnosis procedure (pH, lactate, metformin) was implemented in all diabetic patients with metformin just after their admission to the ED. The pharmacovigilance staff confirmed the MALA cases (defined as pH≤7.35, lactate concentration>5mmol/L) in patients exposed to metformin and after a causality assessment to eliminate other common causes of lactic acidosis. To assess the impact of this new diagnosis procedure, a before-after study was conducted between two groups: a series of cases with intervention (IG; 1/7/2012-30/6/2013) and a control series of past cases without intervention (CG; 1/1/2011-30/6/2012). The main outcome was the relative reduction of mortality rate and length of hospital stay between the two groups.

RESULTS

Thirty-four MALA cases were confirmed in 745 subjects admitted with lactic acidosis, (IG: 12; CG: 22). A higher illness severity score in the IG vs. CG was observed: respectively arterial lactate (14.2±6.9 vs. 8.8±5.8mmol/L, P<0.05), arterial bicarbonate (7.8±4.3 vs. 14.3±6.3mmol/L, P<0.05). The median time up to MALA diagnosis was 20.5 (Q1-Q3: 11.3-38.5) minutes for IG and 55.0 (Q1-Q3: 33.0-132.0) minutes for CG. After procedure implementation, the mortality relative risk reduction was 26.7% (95% CI: -84.3%, 70.8%), and especially 54.2% (95% CI: -265.2%, 94.2%) in the ED. There was no difference in the hospital stay duration between the two groups.

CONCLUSION

While the results were not significant, the study suggests that the implementation of a MALA early diagnosis procedure in all patients with metformin admitted to an ED tends to decrease mortality, especially for serious MALA cases detected earlier.

Metformin-associated lactic acidosis: Current perspectives on causes and risk

Although metformin has become a drug of choice for the treatment of type 2 diabetes mellitus, some patients may not receive it owing to the risk of lactic acidosis. Metformin, along with other drugs in the biguanide class, increases plasma lactate levels in a plasma concentration-dependent manner by inhibiting mitochondrial respiration predominantly in the liver. Elevated plasma metformin concentrations (as occur in individuals with renal impairment) and a secondary event or condition that further disrupts lactate production or clearance (e.g., cirrhosis, sepsis, or hypoperfusion), are typically necessary to cause metformin-associated lactic acidosis (MALA). As these secondary events may be unpredictable and the mortality rate for MALA approaches 50%, metformin has been contraindicated in moderate and severe renal impairment since its FDA approval in patients with normal renal function or mild renal insufficiency to minimize the potential for toxic metformin levels and MALA. However, the reported incidence of lactic acidosis in clinical practice has proved to be very low (<10 cases per 100,000 patient-years). Several groups have suggested that current renal function cutoffs for metformin are too conservative, thus depriving a substantial number of type 2 diabetes patients from the potential benefit of metformin therapy. On the other hand, the success of metformin as the first-line diabetes therapy may be a direct consequence of conservative labeling, the absence of which could have led to excess patient risk and eventual withdrawal from the market, as happened with earlier biguanide therapies. An investigational delayed-release metformin currently under development could potentially provide a treatment option for patients with renal impairment pending the results of future studies. This literature-based review provides an update on the impact of renal function and other conditions on metformin plasma levels and the risk of MALA in patients with type 2 diabetes.

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.

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.

Metformin-associated lactic acidosis

: Metformin is the most commonly prescribed oral antidiabetic agent. Despite a good safety profile in most patients with diabetes, the risk of metformin-associated lactic acidosis is real if safety guidelines are ignored. Experience with 3 cases of metformin-associated lactic acidosis is reported. Two cases were caused by inappropriate use of metformin in the presence of renal, cardiac and hepatic failure and 1 case followed an intentional overdose. The literature was reviewed on the clinical presentation, prevalence, pathogenesis, prognosis and management of metformin-associated lactic acidosis. This report highlights the importance of proper patient selection, clinical and laboratory monitoring and recommendation on when to stop the drug in ambulatory and hospitalized patients to prevent this unusual but potentially lethal complication.

Long-term outcome of critically ill adult patients with acute epiglottitis

Background

Acute epiglottitis is a potentially life threatening disease, with a growing incidence in the adult population. Its long-term outcome after Intensive Care Unit (ICU) hospitalization has rarely been studied.

Methodology and Principal Findings

Thirty-four adult patients admitted for acute epiglottitis were included in this retrospective multicentric study. The mean age was 44±12 years (sex ratio: 5.8). Sixteen patients (47%) had a history of smoking while 8 (24%) had no previous medical history. The average time of disease progression before ICU was 2.6±3.6 days. The main reasons for hospitalization were continuous monitoring (17 cases, 50%) and acute respiratory distress (10 cases, 29%). Microbiological documentation could be made in 9 cases (26%), with Streptococcus spp. present in 7 cases (21%). Organ failure at ICU admission occurred in 8 cases (24%). Thirteen patients (38%) required respiratory assistance during ICU stay; 9 (26%) required surgery. Two patients (6%) died following hypoxemic cardiac arrest. Five patients (15%) had sequelae at 1 year. Patients requiring respiratory assistance had a longer duration of symptoms and more frequent anti inflammatory use before ICU admission and sequelae at 1 year (p<0.05 versus non-ventilated patients). After logistic regression analysis, only exposure to anti-inflammatory drugs before admission was independently associated with airway intervention (OR, 4.96; 95% CI, 1.06-23.16).

Conclusions and Significance

The profile of the cases consisted of young smoking men with little comorbidity. Streptococcus spp. infection represented the main etiology. Outcome was favorable if early respiratory tract protection could be performed in good conditions. Morbidity and sequelae were greater in patients requiring airway intervention.

[Metformin-induced lactic acidosis : Severe symptoms with difficult diagnostics]

Metformin-induced lactic acidosis is a rare but severe disease for the individual patients. A case of a 64-year-old patient with diabetes mellitus type 2 suffering from this disease is presented where metformin accumulation was caused by prerenal acute kidney failure. The clinical evaluation up to the final diagnosis, the pathophysiology and the appropriate therapy are presented in detail. Additionally, the current guidelines regarding the perioperative management of metformin administration are summarized. The case described aims to direct attention to the rare but, nevertheless, severe symptoms of metformin-induced lactic acidosis.

Metformin and its clinical use: new insights for an old drug in clinical practice

Metformin is generally recommended as first-line treatment in type 2 diabetes, especially in overweight patients, but in recent years new indications for its use have emerged. Metformin has been found to be safe and efficacious both as monotherapy and in combination with all oral antidiabetic agents and insulins. If metformin use during pregnancy and the lactation period is supported by few data, it could be indicated for women with polycystic ovary syndrome, since it could diminish circulating androgens and insulin resistance, thus ameliorating the ovulation rate. Metformin seems to reduce cancer risk, which appears to be increased in diabetics, and is a promising agent for oncoprevention and chemotherapy combinations. Moreover, metformin could find a place in the treatment of non-alcoholic fatty liver disease. Lactic acidosis could be decreased by avoiding metformin use in patients with hypovolemia, sepsis, renal impairment, hypoxic respiratory diseases and heart failure, in the preoperative period and before intravenous injection of contrast media.