Lipid emulsion for acute organophosphate insecticide poisoning – a pilot observational safety study

The possible therapeutic role of intravenous lipid emulsion in acute aluminium phosphide poisoning: a randomized controlled clinical trial

Introduction

Aluminum phosphide (ALP) is a highly toxic rodenticide and the mortality rates caused by it have been demonstrated up to 70-100% in various studies. Unfortunately, there is no specific antidote to manage its toxic effects. This study aimed to assess the biochemical and clinical efficacy and safety of intravenous lipid emulsion as an adjuvant therapy in acute aluminum phosphide poisoning.

Patients and methods

Sixty-four cases with acute ALP poisoning were stratified according to severity by the Poison Severity Score into severe and moderate groups (32 patients each). Patients were then randomly allocated into either receiving intravenous lipid emulsion in addition to the conventional treatment or receiving the conventional treatment only by using block randomization.

Results

Treatment by ILE resulted in a significant improvement in the survival time, the mean arterial blood pressure, arterial blood gases, and a significant reduction in serum lactate levels. The need for intubation and mechanical ventilation was insignificantly lower in the intervention groups compared to control groups. However, the reduction in mortality rate in the patients of intervention groups compared with control groups was found to be non-significant. Intravenous lipid emulsion use in acute ALP poisoning significantly prolonged the survival time, improved the metabolic acidosis, decreased the serum lactate levels and increased the mean arterial blood pressure and hospital stay in the intervention groups. And insignificantly decreased the mortality rate, need of intubation and mechanical ventilation, and the total dose of vasopressors.

An in vitro study to determine the impact of lipid emulsion on partitioning of a broad spectrum of drugs associated with overdose

Background

Intravenous lipid emulsion is recognised as a therapy for rescue in cases of local anaesthetic toxicity, but its use in reversing overdose or toxicity related to other drugs remains the subject of debate. This in vitro study sought to expand our understanding of the importance of partitioning in determining the impact of intravenous lipid emulsion on aqueous free drug concentrations.

Methods

Twenty-seven drugs and associated metabolites were screened for the ability of intravenous lipid emulsion to reduce the amount of free drug in the aqueous phase, using specialised cassettes designed for this purpose. The relative amount of drug equilibrating across the membrane from plasma to phosphate-buffered saline was measured, using liquid chromatography-mass spectrometry, at a 6 h timepoint in plasma samples treated with intravenous lipid emulsion and paired, untreated controls.

Results

The data obtained were plotted against measures of partition (LogP and cLogD7.4) and with log-transformed non-protein bound drug. There were significant inverse correlations between the capacity for intravenous lipid emulsion to reduce drug detected in the phosphate-buffered saline compartment and LogP and cLogD7.4, and a direct association with log [non-protein-bound drug]. However, a number of drugs showed substantial variance between different plasma samples.

Conclusions

Modulation of free drug in the aqueous compartment is broadly predictable by the partition coefficient, although ramipril was identified to be an outlier in this regard. Further mechanistic and clinical exploration is merited to establish a standardised protocol for lipid emulsion therapy.

Albuterol as an adjuvant in acute anticholinesterase pesticide poisoning: a randomized, placebo-controlled clinical trial

Acute anticholinesterase pesticide poisoning is a serious clinical problem, particularly in developing countries. Atropine is the most acceptable treatment for acute anticholinesterase poisoning. However, it only stops fluid production. Albuterol is a beta-2 receptor agonist that can increase fluid removal and speed the return of effective oxygen exchange. This study aims to evaluate the safety and efficacy of nebulized albuterol as an adjuvant therapy in patients with acute anticholinesterase poisoning. This stratified block randomized, single-blinded, placebo-controlled, parallel-group clinical trial was conducted between November 2020 and October 2021. It enrolled 80 patients with acute anticholinesterase pesticide poisoning who were admitted to Tanta University Poison Control Center. Patients were allocated into two groups (40 patients each). The strata were based on the severity of poisoning (moderate and severe). Patients in group I received 10 mg of nebulized albuterol. Group II received an equivalent volume of nebulized normal saline. Additionally, standard treatment was provided to both groups. Outcomes included oxygenation, mortality, need for endotracheal intubation and mechanical ventilation, hospital stay duration, time to atropinization, and total doses of atropine and oxime. We found insignificant differences in sociodemographics, exposure characteristics, clinical manifestations, or routine laboratory tests between the studied groups. The median values of oxygen saturation by pulse oximetry were 99% in the albuterol moderate toxicity group and 98% in the control moderate toxicity group. Albuterol significantly improved oxygen saturation in moderate intoxicated patients (P = 0.039). Therefore, nebulized albuterol is a safe drug. Moreover, it may improve oxygenation in acute anticholinesterase pesticide poisoning.

Lipid emulsion therapy during management of the critically-ill poisoned patient: a prospective cohort study

BACKGROUND

Despite conflicting data, intravenous lipid emulsion has emerged as a potential antidote. The "lipid sink" theory suggests that following intravenous administration of lipid, lipophilic drugs are sequestered in the vascular compartment, thereby reducing their tissue concentrations. This study sought to determine if survival is associated with the intoxicant's degree of lipophilicity.

METHODS

We reviewed all cases in the Toxicology Investigators Consortium's lipid sub-registry between May 2012 through December 2018. Information collected included demographics, exposure circumstances, clinical course, management, disposition, and outcome. The primary outcome was survival after lipid emulsion therapy. Survival was stratified by the log of the intoxicant's octanol-water partition coefficient. We also assessed the association between intoxicant lipophilicity and an increase in systolic blood pressure after lipid emulsion administration.

RESULTS

We identified 134 patients, including 81 (60.4%) females. The median age was 40 years (interquartile range 21-75). One hundred and eight (80.6%) patients survived, including 45 (33.6%) with cardiac arrest during their intoxication. Eighty-two (61.2%) were hypotensive, and 98 (73.1%) received mechanical ventilation. There was no relationship between survival and the log of the partition coefficient of the intoxicant on linear analysis (P = 0.89) or polynomial model (P = 0.10). Systolic blood pressure increased in both groups. The median (interquartile range) systolic blood pressure before lipid administration was 68 (60-78) mmHg for those intoxicants with a log partition coefficient < 3.6 compared with 89 (76-104) mmHg after lipid administration. Among those drugs with a log partition coefficient > 3.6, the median (interquartile range) was 69 (60-84) mmHg before lipid and 89 (80-96) mmHg after lipid administration.

CONCLUSION

Most patients in this cohort survived. Lipophilicity was not correlated with survival or the observed changes in blood pressure. The study did not address the efficacy of lipid emulsion.

Lipid emulsion for xenobiotic overdose: PRO

Infusion of lipid emulsion for drug overdose arose as a treatment for local anaesthetic systemic toxicity (LAST) initially based on laboratory results in animal models with the subsequent support of favourable case reports. Following successful translation to the clinic, practitioners also incorporated lipid emulsion as a treatment for non-local anaesthetic toxicities but without formal clinical trials. Recent clinical trials demonstrate a benefit of lipid emulsion in antipsychotic, pesticide, metoprolol and tramadol overdoses. Formal trials of lipid emulsion in LAST may never occur, but alternative analytic tools indicate strong support for its efficacy in this indication; for example, lipid emulsion has obviated the need for cardiopulmonary bypass in most cases of LAST. Herein, we describe the pre-clinical support for lipid emulsion, evaluate the most recent clinical studies of lipid emulsion for toxicity, identify a possible dose-based requirement for efficacy and discuss the limitations to uncontrolled studies in the field.

Role of intravenous lipid emulsion therapy and packed red blood cell transfusion as adjuvant treatment in the management of a child with severe organophosphate poisoning (chlorpyrifos)

A previously well 3-year-old child presented with rapidly deteriorating clinical status minutes after ingestion of an orange-coloured liquid housed in a soda bottle (HomeTrek-chlorpyrifos). She had miotic pupils, copious oral secretions, crackles on lung auscultation, hyperactive bowel sounds, impending signs of respiratory failure and declining sensorium. A diagnosis of severe organophosphate (OP) toxicity was made. Despite resuscitation and atropine administration, she deteriorated and exhibited atropine toxicity. She was given 20% intravenous lipid emulsion therapy and red blood cell (RBC) transfusion as adjunctive therapy with favourable outcome. She was discharged after 11 days and her RBC cholinesterase levels were 45% and 17% below normal, taken on day 10 and day 35 postingestion, respectively. She showed no signs of intermediate syndrome and delayed polyneuropathy. This case highlights the need for timely recognition of severe OP poisoning, and the role of lipid emulsion therapy and packed RBC transfusion as adjunctive treatment.

Lipid emulsion for the treatment of acute organophosphate poisoning: an Open-Label randomized trial

INTRODUCTION

Many organophosphate (OP) pesticides are lipid-soluble; therefore, intravenous lipid emulsion (ILE) has been evaluated as a possible treatment for acute poisoning. A single bolus dose of 100 ml of 20% ILE was found safe in a pilot observational study. This randomized trial aimed to assess the effectiveness and safety of an extended dose of ILE in acute OP poisoning.

METHODS

This was an investigator-initiated, parallel-group, open-label, randomized controlled trial conducted at PGIMER, Chandigarh (India), from January 2019 to June 2020, in patients aged above 13 years with acute OP poisoning. The primary efficacy outcome was to study the change in atropine dose requirement (total and over the first 24 h) for cholinergic crisis after giving an initial bolus dose of 100 ml of 20% ILE followed by an infusion of 100 ml of 20% ILE over 6 h in addition to the standard care. The secondary efficacy outcomes were to detect the effects on hemodynamic variables, length of hospital stay, and duration of mechanical ventilation required. The incidence of adverse events was evaluated.

RESULTS

A total of 45 patients were assigned to receive either ILE (intervention group, n = 23) or normal saline (control group, n = 22) in addition to standard treatment. Baseline variables in both groups were comparable. The median dose of atropine (in mg) in the first 24 h and at complete resolution in the ILE group were similar to the control group (124.0 versus 141.8, p-value 0.916; and 150.8 versus 175.0, p-value 0.935). Hemodynamic variables (systolic and diastolic blood pressures, mean arterial pressure, and pulse rate) over 24, 48, and 72 h of treatment, length of hospital stay, and duration of mechanical ventilation were also unaffected by ILE. Case fatality was 4 and not statistically different between intervention and control groups (1 versus 3, p-value 0.346). There was no excessive fever, dyspnea, elevation of serum amylase, or pancreatitis from ILE.

CONCLUSION

ILE has no apparent benefit in acute OP poisoning. However, an extended dose appears safe for the indication.

Mechanisms and Efficacy of Intravenous Lipid Emulsion Treatment for Systemic Toxicity From Local Anesthetics

Local anesthetics are widely used clinically for perioperative analgesia to achieve comfort in medical treatment. However, when the concentration of local anesthetics in the blood exceeds the tolerance of the body, local anesthetic systemic toxicity (LAST) will occur. With the development and popularization of positioning technology under direct ultrasound, the risks and cases of LAST associated with direct entry of the anesthetic into the blood vessel have been reduced. Clinical occurrence of LAST usually presents as a series of severe toxic reactions such as myocardial depression, which is life-threatening. In addition to basic life support (airway management, advanced cardiac life support, etc.), intravenous lipid emulsion (ILE) has been introduced as a treatment option in recent years and has gradually become the first-line treatment for LAST. This review introduces the mechanisms of LAST and identifies the clinical symptoms displayed by the central nervous system and cardiovascular system. The paper features the multimodal mechanism of LAST reversal by ILE, describes research progress in the field, and identifies other anesthetics involved in the resuscitation process of LAST. Finally, the review presents key issues in lipid therapy. Although ILE has achieved notable success in the treatment of LAST, adverse reactions and contraindications also exist; therefore, ILE requires a high degree of attention during use. More in-depth research on the treatment mechanism of ILE, the resuscitation dosage and method of ILE, and the combined use with other resuscitation measures is needed to improve the efficacy and safety of clinical resuscitation after LAST in the future.

Intravenous lipid emulsion as an adjuvant therapy of acute clozapine poisoning

Introduction:

Clozapine is a frequently prescribed atypical antipsychotic drug. Various case reports documented the successful recovery of acute antipsychotics toxicity in association with the administration of intralipid emulsion (ILE).

Aim:

This study aimed to assess the adjuvant therapeutic role of SMOF Lipid administration on the outcomes of acute clozapine poisoning.

Methods:

Forty patients with acute clozapine poisoning were randomly allocated into two equal groups. The control group received the standard supportive treatment only, whereas the intervention group received the standard supportive treatment plus SMOF Lipid 20% infusion. All patients were subjected to history taking, full clinical examination, and laboratory investigations. The study outcomes were evaluated.

Results:

The mean Glasgow Coma Scale (GCS) at 6 hours (13.1 ± 2.3 vs 9.2 ± 2, p < 0.001) and 12 hours (14.3 ± 1.5 vs 9.6 ± 2, p < 0.001) after admission was significantly higher in the intervention group compared to the control group. The intervention group showed a significantly lower frequency of prolonged QTc interval 12 hours after admission (p = 0.003), as well as a significantly shorter hospital stay (p < 0.001).

Conclusions:

SMOF Lipid infusion seemed to have improved GCS, the prolonged QTc interval, and shortened the length of hospital stay. Furthermore, there were no adverse effects related to its administration.

Heterogeneity and bias in animal models of lipid emulsion therapy: a systematic review and meta-analysis

INTRODUCTION

Clinicians utilize lipid emulsion to treat local anesthetic toxicity and non-local anesthetic toxicities, a practice supported by animal experimentation and clinical experience. Prior meta-analysis confirmed a mortality benefit of lipid emulsion in animal models of local anesthetic toxicity but the benefit of lipid emulsion in models of non-local anesthetic toxicity remains unanswered. Further, swine suffer an anaphylactoid reaction from lipid emulsions calling into question their role as a model system to study lipid, so we examined swine and non-swine dependent outcomes in models of intravenous lipid emulsion.

METHODS

We conducted a systematic review and meta-analysis examining the use of lipid emulsion therapy in animal models of cardiac toxicity. We quantified mortality using a random-effects odds-ratio method. Secondary outcomes included survival in the following subgroups: local-anesthetic systemic toxicity, non-local anesthetic toxicity, swine-based models, and non-swine models (e.g., rat, rabbit and dog). We assessed for heterogeneity with Cochran's Q and I². We examined bias with Egger's test & funnel plot analysis.

RESULTS

Of 2784 references screened, 58 met criteria for inclusion. Treatment with lipid emulsion reduced chance of death in all models of toxicity with an odds ratio of death of 0.26 (95% CI 0.16-0.44, Z-5.21, p < 0.00001, Cohen's-d = 0.72, n = 60). Secondary outcomes confirmed a reduced chance of death in models of local anesthetic toxicity (OR 0.16 {95% CI 0.1-0.33}) and non-local anesthetic toxicity (OR 0.43 {95% CI 0.22-0.83}). Heterogeneity (Cochran's Q 132 {df = 59, p < 0.01}, I ² = 0.55) arose primarily from animal-model and disappeared (I ² < = 0.12) when we analyzed swine and non-swine subgroups independently. Swine only benefited in models of local anesthetic toxicity (OR 0.28 {95% CI 0.11-0.7}, p = 0.0033) whereas non-swine models experienced a homogeneous benefit across all toxins (OR 0.1 {95% CI 0.06-0.16}, p < 0.00001). Egger's test identified risk of bias with outliers on funnel plot analysis.

DISCUSSION

Lipid emulsion therapy reduces mortality in animal models of toxicity. Heterogeneity arises from the animal-model used. Swine only benefit in models of local anesthetic toxicity, potentially due to lipid dose, experimental design or swine's anaphylactoid reaction to lipid. Outlier analysis reinforced the need for appropriate dosing of lipid emulsion along with airway management and chest compressions in the setting of cardiac arrest.

Effective management of acute postoperative pain using intravenous emulsions of novel ketorolac prodrugs: in vitro and in vivo evaluations

The aim was to prepare intravenous fat emulsions (IFEs) of ketorolac (KTL) ester prodrugs and to investigate the pharmacokinetics and pharmacodynamics of these formulations. Three prodrugs of KTL (KTL-IS, KTL-AX and KTL-BT) were synthesized as a means to increase the lipid solubility of KTL. All KTL prodrugs with higher Log P values presented increased tendency to partition into a blank IFE using extemporaneous addition method - the encapsulation efficiency of KTL-IS IFE and KTL-BT IFE was more than 97%. The particle sizes and zeta potentials of these two formulations were comparable to that of the blank IFE. PK studies in rabbits showed significant larger AUC0-8h (646.969 ± 154.326 mg/L•h-1 for KTL-IS IFE and 559.426 ± 103.057 mg/L•h-1 for KTL-BT IFE) than that of ketorolac tromethamine (KTL-T) injectable (286.968 ± 63.045 mg/L•h-1) and approximately 2-fold increases in the elimination t1/2 over KTL-T. In a rat postoperative pain model, the paw withdrawal thresholds and the paw withdrawal latency after I.V. KTL prodrug IFEs were significantly higher than that after I.V. KTL-T at 3~4 h. Effective controlling of acute postoperative pain in a longer duration can be achieved by using non-addictive ketorolac derivatives intraveneous emulsions.