Treatment of severe metformin-associated lactic acidosis with renal replacement therapy and tris-hydroxymethyl aminomethane: a case report

BACKGROUND

Type B lactic acidosis is a rare but serious side effect of metformin use. The risk of metformin-associated lactic acidosis is elevated in renal or liver impairment, heart failure and in metformin overdose. Metformin-associated lactic acidosis is treated with renal replacement therapy although this can be limited by metformin's large volume of distribution and a patient's hemodynamic instability. Tris-hydroxymethyl aminomethane is a buffer that rapidly equilibrates in liver cells and increases the intracellular pH of hepatocytes. Intracellular alkalosis increases lactate uptake by the liver and can promote gluconeogenesis which results in increased lactate metabolism and decreased lactate production. Unlike intravenous bicarbonate which can worsen acidosis due to carbon dioxide retention and hypocalcemia, tris-hydroxymethyl aminomethane does not generate large amounts of carbon dioxide and can improve cardiac contractility in experimental models.

CASE PRESENTATION

We present a case of a 43-year-old African American male who intentionally ingested 480,000 g of metformin. He developed severe metformin-associated lactic acidosis that was refractory to 21 hours of high flux hemodialysis. This was followed by an additional 12 hours of high flux hemodialysis augmented by continuous intravenous infusion of tris-hydroxymethyl aminomethane. After initiating tris-hydroxymethyl aminomethane, the patient had rapid reversal of lactic acidosis and was weaned off vasopressors and mechanical ventilation.

CONCLUSIONS

While metformin-associated lactic acidosis can be treated with renal replacement therapy, severe cases of lactic acidosis may not be amenable to renal replacement therapy alone. Through its unique buffer mechanisms, tris-hydroxymethyl aminomethane can be used in conjunction with dialysis to rapidly improve acidosis associated with metformin.

High risk and low prevalence diseases: Metformin toxicities

INTRODUCTION

Metformin toxicity is a rare but serious condition that carries with it a high rate of morbidity and mortality.

OBJECTIVE

This review highlights the pearls and pitfalls of metformin toxicity, including diagnosis, initial resuscitation, and management in the emergency department (ED) based on current evidence.

DISCUSSION

Metformin is a common medication used for treatment of diabetes mellitus. Metformin toxicity is a spectrum of conditions that may be differentiated into three subgroups: metformin-associated lactic acidosis (MALA), metformin-induced lactic acidosis (MILA), and metformin-unrelated lactic acidosis (MULA). MILA is a condition found predominantly in patients chronically taking metformin or those with large acute overdoses. Conversely, MULA occurs in patients on metformin but with a critical illness stemming from a separate cause. MALA is rare but the most severe form, with mortality rates that reach 50%. Differentiating these entities is difficult in the ED setting without obtaining metformin levels. Patients with metformin toxicity present with nonspecific gastrointestinal symptoms and vital sign abnormalities. Laboratory analysis will reveal a high lactate with anion gap metabolic acidosis. Patients presenting with elevated lactate levels in the setting of metformin use should be considered at risk for the most severe form, MALA. Patients with MALA require aggressive treatment with intravenous fluids, treatment of any concomitant condition, and early consideration of hemodialysis, along with specialist consultation such as nephrology and toxicology.

CONCLUSIONS

An understanding of metformin toxicity can assist emergency clinicians in diagnosing and managing this potentially deadly disease.

Safety of metformin continuation in diabetic patients undergoing invasive coronary angiography: the NO-STOP single arm trial

BACKGROUND

Despite paucity of data, it is common practice to discontinue metformin before invasive coronary angiography due to an alleged risk of Metformin-Associated Lactic Acidosis (M-ALA). We aimed at assessing the safety of metformin continuation in diabetic patients undergoing coronary angiography in terms of significant increase in lactate levels.

METHODS

In this open-label, prospective, multicentre, single-arm trial, all diabetic patients undergoing coronary angiography with or without percutaneous coronary intervention at 3 European centers were screened for enrolment. The primary endpoint was the increase in lactate levels from preprocedural levels at 72-h after the procedure. Secondary endpoints included contrast associated-acute kidney injury (CA-AKI), M-ALA, and all-cause mortality.

RESULTS

142 diabetic patients on metformin therapy were included. Median preprocedural lactate level was 1.8 mmol/l [interquartile range (IQR) 1.3-2.3]. Lactate levels at 72 h after coronary angiography were 1.7 mmol/l (IQR 1.3-2.3), with no significant differences as compared to preprocedural levels (p = 0.91; median difference = 0; IQR - 0.5 to 0.4 mmol/l). One patient had 72-h levels ≥ 5 mmol/l (5.3 mmol/l), but no cases of M-ALA were reported. CA-AKI occurred in 9 patients (6.1%) and median serum creatinine and estimated glomerular filtration rate remained similar throughout the periprocedural period. At a median follow-up of 90 days (43-150), no patients required hemodialysis and 2 patients died due to non-cardiac causes.

CONCLUSIONS

In diabetic patients undergoing invasive coronary angiography, metformin continuation throughout the periprocedural period does not increase lactate levels and was not associated with any decline in renal function.

TRIAL REGISTRATION

The study was registered at Clinicaltrials.gov (NCT04766008).

Metformin-associated lactic acidosis and acute kidney injury in the era of COVID-19

COVID-19, provoked by SARS-CoV-2, constitutes a global health issue with high rates of mortality. The presence of diabetes mellitus is associated with severe coronavirus COVID-19 as it is related to increased death rates in patients admitted to the intensive care unit. Acute kidney injury is a frequent complication among patients hospitalized for COVID-19 and is met with high morbidity and mortality. Here, we present a case of a diabetic patient with acute kidney injury, metformin-associated lactic acidosis, and COVID-19. Lactic acidosis is a relatively rare but noteworthy complication of metformin use. However, the combination of those life-threatening situations could prove fatal for the patients despite optimal medical care.

Mechanism and application of metformin in kidney diseases: An update

Metformin is an oral antihyperglycemic drug widely used to treat type 2 diabetes mellitus (T2DM), acting via indirect activation of 5' Adenosine monophosphate-activated Protein Kinase (AMPK). Beyond the anti-diabetic effect, accumulative pieces of evidence have revealed that metformin also everts a beneficial effect in diverse kidney diseases. In various acute kidney diseases (AKI) animal models, metformin protects renal tubular cells from inflammation, apoptosis, reactive oxygen stress (ROS), endoplasmic reticulum (ER) stress, epithelial-mesenchymal transition (EMT) via AMPK activation. In diabetic kidney disease (DKD), metformin also alleviates podocyte loss, mesangial cells apoptosis, and tubular cells senescence through AMPK-mediated signaling pathways. Besides, metformin inhibits cystic fibrosis transmembrane conductance regulator (CFTR)-mediated fluids secretion and the mammalian target of rapamycin (mTOR)-involved cyst formation negatively regulated by AMPK in autosomal dominant polycystic kidney disease (APDKD). Furthermore, metformin also contributes to the alleviation of urolithiasis and renal cell carcinoma (RCC). As the common pathway for chronic kidney disease (CKD) progressing towards end-stage renal disease (ESRD), renal fibrosis is ameliorated by metformin, to a great extent dependent on AMPK activation. However, clinical data are not always consistent with preclinical data, some clinical investigations showed the unmeaningful even detrimental effect of metformin on T2DM patients with kidney diseases. Most importantly, metformin-associated lactic acidosis (MALA) is a vital issue restricting the application of metformin. Thus, we conclude the application of metformin in kidney diseases and uncover the underlying molecular mechanisms in this review.

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.

Application of a Pharmacokinetic Model of Metformin Clearance in a Population with Acute Myeloid Leukemia

OBJECTIVE

We aimed to estimate the metformin-associated lactic acidosis (MALA) risk by assessing retrospectively the renal clearance variability and applying a pharmacokinetic (PK) model of metformin clearance in a population diagnosed with acute myeloid leukemia (AML) and diabetes mellitus (DM).

METHODS

All adults with preexisting DM and newly diagnosed AML at Roswell Park Cancer Institute were reviewed (January 2003-December 2010, n = 78). Creatinine clearance (CrCl) and total body weight distributions were used in a two-compartment PK model adapted for multiple dosing and modified to account for actual intra- and inter-individual variability. Based on this renal function variability evidence, 1000 PK profiles were simulated for multiple metformin regimens with the resultant PK profiles being assessed for safe CrCl thresholds.

FINDINGS

Metformin 500 mg up to three times daily was safe for all simulated profiles with CrCl ≥25 mL/min. Furthermore, the estimated overall MALA risk was below 10%, remaining under 5% for 500 mg given once daily. CrCl ≥65.25 mL/min was safe for administration in any of the tested regimens (500 mg or 850 mg up to three times daily or 1000 mg up to twice daily).

CONCLUSION

PK simulation-guided prescribing can maximize metformin's beneficial effects on cancer outcomes while minimizing MALA risk.