Lipid Emulsion to Treat Acute Poisonings: Mechanisms of Action, Indications, and Controversies

Environmental behavior, risks, and management of antidepressants in the aquatic environment

Antidepressants are increasingly detected in aquatic environments due to their incomplete removal in wastewater treatment, raising significant concerns about their ecological impacts. This review focuses on the three most widely used classes of antidepressants-tricyclic antidepressants (TCAs), selective serotonin reuptake inhibitors (SSRIs), and serotonin-norepinephrine reuptake inhibitors (SNRIs). It systematically explores their physicochemical properties and how these properties influence their environmental fate, including sorption, mobility, and bioaccumulation in aquatic ecosystems. The sublethal effects of these antidepressants on aquatic organisms, particularly their impacts on behavior, reproduction, and development, are critically analyzed, highlighting potential threats to biodiversity and ecological stability. Key knowledge gaps are identified, including the long-term impacts of chronic low-dose exposure, the role of bioactive metabolites, and the combined toxicity of antidepressants with other contaminants. The review underscores the importance of advanced wastewater treatment technologies, environmentally mindful prescribing practices, and public awareness campaigns as essential measures to mitigate these risks. By addressing these challenges, this study aims to inform future research and guide sustainable environmental management strategies.

Refractory Hyperkalemia With Type 4 Renal Tubular Acidosis Associated With Tubulointerstitial Nephritis and Renal Papillary Necrosis Following Intravenous Lipid Emulsion Therapy in a Cat

OBJECTIVE

To describe type 4 renal tubular acidosis (RTA) and acquired pseudohypoaldosteronism in a cat with acute kidney injury (AKI) presumably associated with lipid infusion therapy for permethrin toxicosis.

CASE SUMMARY

A 1-year-old neutered male cat presented with acute weakness, ataxia, fasciculations, tremors, hyperthermia, and seizures resulting from permethrin toxicosis. Upon admission, IV diazepam and 20% IV lipid emulsion were administered. Forty-eight hours after discharge, the patient was readmitted for lethargy, anorexia, polyuria, and vomiting. Upon admission, the patient exhibited signs of depression, dehydration, and moderate hypoperfusion. Initial assessments included CBC, serum biochemistry profile, and urinalysis. Further diagnostic workup and abdominal point-of-care ultrasound revealed clinical findings compatible with AKI. Laboratory analysis confirmed severe hyperkalemia, hyperchloremic normal anion gap metabolic acidosis, decreased fractional excretion of potassium, and decreased transtubular potassium gradient in the urine, all consistent with a diagnosis of secondary or acquired pseudohypoaldosteronism and type 4 RTA. Emergency medical treatment for hyperkalemia was initiated, but control of serum potassium concentration was unsuccessful. Peritoneal dialysis (PD) and general supportive care were initiated 24 h after admission. Mineralocorticoid support (continuous rate infusion of hydrocortisone) was initiated 4 days after admission due to suspected deficiency/resistance to aldosterone at the distal nephron. Unfortunately, despite PD, refractory hyperkalemia persisted, and the cat died 16 days after admission. Histopathological examination confirmed an acute and severe renal papillary necrosis.

NEW OR UNIQUE INFORMATION

To the authors' knowledge, this is the first description of type 4 RTA in a cat. Furthermore, we hypothesize that, according to the histopathological findings, this presentation of AKI may be secondary to the use of IV lipid emulsion for permethrin toxicosis, a complication not previously reported in the veterinary literature.

The preventive efficacy of lipid emulsion on the occurrence of local anesthetic systemic toxicity in patients receiving local infiltration analgesia for total joint arthroplasty

BACKGROUND

Motor-sparing local infiltration analgesia (LIA) enhances recovery after total hip arthroplasty (THA) and total knee arthroplasty (TKA). However, LIA can induce local anesthetic systemic toxicity (LAST), sometimes necessitating rescue lipid emulsion therapy. Our institute initiated a pilot study to pretreat patients with lipid emulsion (SMOFlipid®) to test its efficacy in mitigating LIA-induced LAST events.

METHODS

This retrospective study enrolled 1,621 adult patients who received LIA with bupivacaine (2-3 mg/kg, maximum 300 mg) for unilateral primary THA or TKA under general anesthesia between January 2020 and April 2022. A total of 439 patients received lipid pretreatment, while 1,182 did not. Demographics, surgical and anesthesia profiles, along with LAST events affecting the neurological, cardiovascular, and respiratory systems, were compared after propensity score matching for age, sex, body mass index (BMI), and surgery type.

RESULTS

The incidence of severe LAST events requiring rescue lipid emulsion slightly decreased after lipid pretreatment (from 2.54 to 2.28 per 1000). Lipid pretreatment significantly reduced the incidence of bradycardia and new-onset arrhythmia (odds ratio: 0.13, adjusted p-value: 0.024) but increased postoperative opioid requirement (odds ratio: 1.71, adjusted p-value: 0.032) after Benjamini-Hochberg correction for multiplicity.

CONCLUSIONS

The efficacy of lipid pretreatment (SMOFlipid® 1.5 ml/kg, maximum 100 ml) in mitigating LIA-induced LAST remains controversial. While lipid pretreatment reduced the incidence of new-onset arrhythmia, it showed no clear benefits for neurologic and respiratory outcomes. Additionally, lipid pretreatment might hinder postoperative recovery by increasing the need for rescue opioid analgesia. Further prospective pharmacokinetic studies are required to assess plasma bupivacaine concentrations following LIA and lipid pretreatment, examine their relationship to LAST events, and establish the efficacy and safety of lipid pretreatment.

A novel method in myocardial injury risk stratification using intravenous fat emulsion as sole rapid preparation for unfasted patients to suppress myocardial 18F-fluorodeoxyglucose uptake for optimal cardiac PET imaging: a proof-of-concept randomized-crossover trial

Objectives

Optimal imaging of ischemic or inflammed myocardium via 18F-FDG PET imaging requires suppression of background carbohydrate metabolism in normal myocardium. Sole administration of intravenous lipid emulsion has not previously been used to rapidly prepare unfasted patients, such as in emergent clinical situations. In this proof-of-concept pilot, we posited that intravenous fat emulsion suppresses physiological metabolic uptake of in non-ischemic, non-inflammatory myocardium in unprepared and unfasted setting for enhanced cardiac positron emission tomography (PET) imaging.

Methods

We conducted an ethics-approved, single-blind, prospective randomized crossover trial of 10 healthy volunteers from January 2020 to June 2021. Participants were unfasted and rendered hyperglycemic before being administered either high dose intravenous lipid emulsion-1.5 ml kg of 20% lipid emulsion, followed by 15 ml/kg/hr for 30mins-or saline prior to 18F-FDG injection and subsequent cardiac PET imaging. Assessors undertook image analysis for maximum standard uptake value (SUVmax), minimum standard uptake value (SUVmin) and qualitative assessment, and groups were compared using univariate analysis.

Results

The study population age was 44.5 years [IQR 32.5-56.5], with 50% male and a median BMI of 22.75 [IQR 25.0-28.5] kg/m2. The study was feasible and there were no adverse side effects from the interventions. In these participants with normal myocardium, 18F-FDG uptake was reduced by intravenous lipid emulsion as assessed by SUVmax and qualitative assessment (p = 0.042, r = 0.454 and p = 0.009, r = -0.581, respectively).

Conclusions

Intravenous lipid emulsion suppresses background metabolic uptake of 18F-FDG even in unprepared and unfasted patients. Our findings prove and expand the possible applications for cardiac 18F-FDG PET in various settings, including in emergent settings as a means of rapid preparation in place of current more time-consuming standard protocols, allowing time-critical management to be effected.

An in vitro evaluation of intravenous lipid emulsion on three common canine toxicants

Objective

To determine whether intravenous lipid emulsion (ILE) therapy significantly reduces the concentration of baclofen, ibuprofen, and/or bromethalin in canine whole blood over time.

Animals

Seven 500 mL bags of canine DEA 1.1 negative blood were divided into aliquots of 125 mL and randomly assigned to one of three treatment groups (baclofen, ibuprofen, bromethalin) or four control groups (a positive control for each treatment group and a negative control group).

Procedures

Injectable ibuprofen (200 mg/kg), baclofen (8 mg/kg), or bromethalin (3 mg/kg) was apportioned into 125 mL aliquots of canine whole blood and incubated for 30 min at 38.5°C. ILE (12.4 mL, Intralipid® ) was added to each sample and the solution vortexed [215 rpm for 15 min at 37°C (98.6°F)]. Samples were obtained at designated time points (0, 15, 30, 60, 180, 360 min), centrifuged, and separated into serum and RBC fractions. Serum samples were ultracentrifuged (22,000 g for 10 min at 37°C) to separate lipid rich and poor fractions. Samples were stored at -80°C prior to analysis.

Results

A significant decrease in total drug concentration was established for bromethalin and its metabolite desmethylbromethalin compared to positive controls. ILE significantly reduced desmethylbromethalin at the 30-and 360-min time points. The remainder of the desmethylbromethalin time points did not reach significance. Bromethalin concentration was significantly reduced at all time points compared to positive controls. Neither baclofen nor ibuprofen had significant changes in concentration.

Conclusion

ILE therapy was effective at reducing the total drug concentration of bromethalin and its metabolite desmethylbromethalin supporting the lipid sink theory. As a single compartment in vitro study, this study does not evaluate other proposed mechanisms of action of ILE therapy. ILE therapy may have other means of significantly decreasing lipophilic drug concentration in cases of toxicosis.

Lipid emulsion attenuates vasodilation by decreasing intracellular calcium and nitric oxide in vascular endothelial cells

Lipid emulsion (LE), a widely used parenteral nutrition, exhibits a well-documented ability to reverse the vasodilatory effects induced by acetylcholine in blood vessels. However, the specific mechanisms underlying this action are not yet fully understood. This study aimed to elucidate the mechanism by which LE reverses vasodilation in vitro through dose-response curve experiments, calcium imaging, and fluorescence assays. The results revealed a significant attenuation of acetylcholine (Ach)-induced vasodilation in rat thoracic aortic rings following LE exposure. In human aortic endothelial cells, pretreatment with LE significantly suppressed ATP-induced calcium elevation. This suppression persisted even after elimination of extracellular calcium with a calcium chelator. Moreover, LE pre-exposure reduced the intracellular calcium concentration ([Ca2+]i) elevation in endothelial cells following cyclopiazonic acid (CPA) treatment, suggesting enhanced endoplasmic reticulum (ER) calcium reuptake. Additionally, nitric oxide (NO) fluorescence assays showed a decrease in NO production upon ATP stimulation post-LE pretreatment of endothelial cells. Taken together, these results indicate that the reversal of vasodilation by LE may involve enhanced ER calcium uptake, leading to a reduction in intracellular calcium concentration and suppression of NO (key vasodilatory agent) synthesis.

A review of local anesthetic-induced heart toxicity using human induced pluripotent stem cell-derived cardiomyocytes

Local anesthetic (LA) cardiotoxicity is one of the main health problems in anesthesiology and pain management. This study reviewed the reported LA-induced cardiac toxicity types, risk factors, management, and mechanisms, with attention to the use of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in heart toxicity research. Important scientific databases were searched to find relevant articles. We briefly assessed the reported cardiotoxic effects of different types of LA drugs, including ester- and amide-linked LA agents. Furthermore, cardiotoxic effects and clinical manifestations, strategies for preventing and managing LA-induced cardiotoxic effects, pharmacokinetics, pharmacodynamics, and sodium channel dynamics regarding individual variability and genetic influences were discussed in this review. The applications and importance of hiPSC-CMs cellular model for evaluating the cardiotoxic effects of LA drugs were discussed in detail. This review also explored hiPSC-CMs' potential in risk assessment, drug screening, and developing targeted therapies. The main mechanisms underlying LA-induced cardiotoxicity included perturbation in sodium channels, ROS production, and disorders in the immune system response due to the presence of LA drugs. Furthermore, drug-specific characteristics including pharmacokinetics and pharmacodynamics are important determinants after LA drug injection. In addition, individual patient factors such as age, comorbidities, and genetic variability emphasize the need for a personalized approach to mitigate risks and enhance patient safety. The strategies outlined for the prevention and management of LA cardiotoxicity underscore the importance of careful dosing, continuous monitoring, and the immediate availability of resuscitation equipment. This comprehensive review can be used to guide future investigations into better understanding LA cardiac toxicities and improving patient safety.

Clinical features of seven patients poisoned with a tolfenpyrad-based insecticide in Thailand

INTRODUCTION

Tolfenpyrad, a novel insecticide originating from Japan and first approved in 2002, has been marketed in numerous countries. Data on tolfenpyrad exposure in humans are limited. This study aimed to characterize the clinical features and outcomes of acute poisoning from tolfenpyrad-based insecticides in Thailand.

METHODS

This retrospective study analyzed cases of tolfenpyrad exposure reported to the Ramathibodi Poison Center from 2012 to 2022.

RESULTS

A total of seven patients were identified, with the majority being male (n = 5). Deliberate tolfenpyrad exposure accounted for three cases. The median age was 33 (range 1-46) years. Severe systemic effects were evident at presentation in the four patients ingesting tolfenpyrad. These included altered mental status (n = 4), mydriasis (n = 2), cardiac arrest (n = 1), hypotension (n = 4), bradycardia (n = 2), and high anion gap metabolic acidosis (n = 4). The median time from exposure to hospital presentation was 30 (range 15-60) minutes. All four patients ingesting tolfenpyrad died, whereas the three patients exposed via inhalation and dermally developed only mild clinical effects, and all were discharged following supportive care.

DISCUSSION

We observed many of the clinical features reported previously, including vomiting, mydriasis, altered mental status, metabolic acidosis, and hypotension. We also noted a combination of bradycardia and hypotension while not observing respiratory depression.

CONCLUSIONS

Tolfenpyrad insecticide poisoning has been reported infrequently. Rapid systemic toxicity can follow ingestion, resulting in a high mortality. Larger-scale studies are essential to identify predictors of severity and determine the optimal treatment for tolfenpyrad-poisoned patients.

Local Anesthetic Systemic Toxicity (LAST): More Common Than You Think

The number of anesthetic body procedures in the United States is rapidly increasing, with many being performed on an outpatient basis. These procedures are advertised as being safe, and many times the serious complications may not be discussed. Although local anesthetic systemic toxicity is a rare complication, it is associated with an increase in morbidity. The emergency department staff should be aware of the possibility of this rare complication, as well as the variety of resulting symptoms (from minor to severe), potential sequelae, and appropriate management for patients who have undergone an outpatient anesthetic body procedure. Multiple factors contribute to the development of local anesthetic systemic toxicity, resulting in life-threatening effects on the neurologic and cardiovascular systems. Also, the site of administration, along with the local anesthetic agent used, can impact the risk of the development of local anesthetic systemic toxicity. To minimize the risk and ensure the best possible outcome for these patients, emergency department staff must be highly aware of the mechanisms, risk factors, prevention, and management/treatment of local anesthetic systemic toxicity.

Metabolic management of accidental intoxication

PURPOSE OF REVIEW

Unintentional intoxication comprises a major chunk of all intoxications. Most patients are in the pediatric age group with another set of patients being the elderly. Substances found to cause accidental intoxication vary from country to country and even within different regions of a country. Frequent reviews of current literature are needed to be abreast of trends.

RECENT FINDINGS

Prescription drugs and household chemicals are major culprits when it comes to accidental intoxication. Acetaminophen, digoxin and metformin are some of the prominent prescription drugs frequently associated with unintentional intoxications. Increasingly alcohol based hand sanitizers are becoming an important etiology of these events, following their increased usage during the COVID-19 pandemic. Pattern recognition to identify class of intoxicant and supportive care including prevention of further absorption and increased excretion are cornerstones of therapy. Antidote when available should be used promptly.

SUMMARY

Knowledge about current epidemiology of accidental intoxications, toxidrome pattern recognition and appropriate antidote usage beside adequate and timely supportive care help in successful management of the unfortunate victim of accidental intoxication.

Case report: Treatment of cyclobenzaprine ingestion in two dogs with intravenous intralipid therapy

Introduction

The objective of this case series is to describe the clinical signs and outcome of cyclobenzaprine ingestion in two dogs treated with intralipid emulsion (ILE) and supportive care.

Case or series summary

Two dogs presented for evaluation of cyclobenzaprine ingestion. A 4-year-old female spayed Rat Terrier (dog 1) presented within 4 h of ingestion of cyclobenzaprine (between 9.7 and 25.9 mg/kg). The dog experienced abnormal behavior, agitation, tremors, tachycardia, and hypertension. There were no significant clinicopathological abnormalities. The dog was treated with ILE, cyproheptadine, and activated charcoal. All clinical signs resolved after treatment. A 5-month-old female intact mixed-breed dog (dog 2) presented after ingestion of an unknown amount of cyclobenzaprine 2-3 h prior to presentation. The dog experienced dull mentation, tremors, loss of gag reflex, tachycardia, and hypertension. There were no significant clinicopathological abnormalities. Orogastric decontamination was performed via gastric lavage, and activated charcoal was given via orogastric tube, followed by ILE. All clinical signs resolved after therapeutic intervention.

Discussion

This is the first report documenting clinical signs of cyclobenzaprine toxicity in two dogs followed by successful treatment with gastric emptying, ILE, and supportive care.

Biodetoxification Using Intravenous Lipid Emulsion, a Rescue Therapy in Life-Threatening Quetiapine and Venlafaxine Poisoning: A Case Report

The administration of intravenous lipid emulsion (ILE) is a proven antidote used to reverse local anesthetic-related systemic toxicity. Although the capacity of ILE to generate blood tissue partitioning of lipophilic drugs has been previously demonstrated, a clear recommendation for its use as an antidote for other lipophilic drugs is still under debate. Venlafaxine (an antidepressant acting as a serotonin-norepinephrine reuptake inhibitor (SNRI)) and quetiapine (a second-generation atypical antipsychotic) are widely used in the treatment of psychotic disorders. Both are lipophilic drugs known to induce cardiotoxicity and central nervous depression. We report the case of a 33-year-old man with a medical history of schizoaffective disorder who was admitted to the emergency department (ED) after having been found unconscious due to a voluntary ingestion of 12 g of quetiapine and 4.5 g of venlafaxine. Initial assessment revealed a cardiorespiratory stable patient but unresponsive with a GCS of 4 (M2 E1 V1). In the ED, he was intubated, and gastric lavage was performed. Immediately after the admission to the intensive care unit (ICU), his condition quickly deteriorated, developing cardiovascular collapse refractory to crystalloids and vasopressor infusion. Junctional bradycardia occurred, followed by spontaneous conversion to sinus rhythm. Subsequently, frequent ventricular extrasystoles, as well as patterns of bigeminy, trigeminy, and even episodes of non-sustained ventricular tachycardia, occurred. Additionally, generalized tonic-clonic seizures were observed. Alongside supportive therapy, antiarrhythmic and anticonvulsant therapy, intravenous lipid emulsion bolus, and continuous infusion were administered. His condition progressively improved over the following hours, and 24 h later, he was tapered off the vasopressor. On day 2, the patient repeated the cardiovascular collapse and a second dose of ILE was administered. Over the next few days, the patient's clinical condition improved, and he was successfully weaned off ventilator and vasopressor support. ILE has the potential to become a form of rescue therapy in cases of severe lipophilic drug poisoning and should be considered a viable treatment for severe cardiovascular instability that is refractory to supportive therapy.