Lipid Emulsion as Rescue Therapy in Lamotrigine Overdose

The Roller Coaster of Lamotrigine Levels: Successful Treatment of Massive Lamotrigine Overdose With Continuous Veno-Venous Hemodiafiltration and Rifampin

Lamotrigine is a commonly used anticonvulsant in treating seizures and bipolar disorder, but there is very limited literature on the management of its toxicity. Case reports have been published suggesting the potential role of hemodialysis in lowering serum lamotrigine levels, as well as sodium bicarbonate and lipid emulsion in treating dysrhythmia. After previously reported therapies failed to stabilize the patient's condition, the case presents our successful treatment experience using continuous veno-venous hemodiafiltration (CVVHDF) to stabilize lamotrigine levels, as well as intravenous rifampin as adjunctive therapy to facilitate lamotrigine metabolism. This is a 66-year-old male who was found unresponsive after a lamotrigine overdose. His first lamotrigine level was 42.3 ug/mL. Hemodialysis was started on hospital day 1. Despite hemodialysis sessions, his lamotrigine level rebounded with worsening neurological and cardiac symptoms. On hospital day 3, he developed wide-QRS complex tachyarrhythmia and hemodynamic instability with a lamotrigine level of 66.9 ug/mL. Sodium bicarbonate was given without effect. Lipid emulsion was administered which terminated the arrhythmia. CVVHDF and rifampin were started and lamotrigine levels have continuously downtrended since. He was successfully extubated on day 7. Lamotrigine level became undetectable on day 9. The patient was discharged to a psychiatric facility without any neurological or mobility impairment on day 10. The continuous drug clearance provided by CVVHDF over intermittent hemodialysis may have provided additional benefit in lamotrigine level stabilization, while rifampin use in this case may have further accelerated lamotrigine metabolism. As the first case reporting CVVHDF and rifampin use, our experience suggests their potential roles in managing severe lamotrigine toxicity.

Effect of lipid emulsion on neuropsychiatric drug-induced toxicity: A narrative review

Lipid emulsion has been shown to effectively relieve refractory cardiovascular collapse resulting from toxic levels of nonlocal anesthetics. The goal of this study was to examine the effect of lipid emulsions on neuropsychiatric drug-induced toxicity using relevant case reports of human patients, with a particular focus on the Glasgow Coma Scale (GCS) score and corrected QT interval, to analyze drugs that frequently require lipid emulsion treatment. The following keywords were used to retrieve relevant case reports from PubMed: "antidepressant or antipsychotic drug or amitriptyline or bupropion or citalopram or desipramine or dosulepin or dothiepin or doxepin or escitalopram or fluoxetine or haloperidol or olanzapine or phenothiazine or quetiapine or risperidone or trazodone" and "lipid emulsion or Intralipid." Lipid emulsion treatment reversed the corrected QT interval prolongation and decreases in Glasgow Coma Scale scores caused by toxic doses of neuropsychiatric drugs, especially lipid-soluble drugs such as amitriptyline, trazodone, quetiapine, lamotrigine, and citalopram. The log P (octanol/water partition coefficient) of the group which required more than 3 lipid emulsion treatments was higher than that that of the group which required less than 3 lipid emulsion treatments. The main rationale to administer lipid emulsion as an adjuvant was as follows: hemodynamic depression intractable to supportive treatment (88.3%) > lipophilic drugs (8.3%) > suspected overdose or no spontaneous breathing (1.6%). Adjuvant lipid emulsion treatment contributed to the recovery of 98.30% of patients with neuropsychiatric drug-induced toxicity. However, further analyses using many case reports are needed to clarify the effects of lipid emulsion resuscitation.

The assessment of cardiac risk in patients taking lamotrigine; a systematic review

OBJECTIVE

The Food and Drug Administration (FDA) warned about lamotrigine's arrhythmogenicity based on in vitro data. This systematic review investigates lamotrigine's effect on cardiac conduction and risk of sudden cardiac death (SCD) in individuals with and without cardiovascular disease.

METHODS

We searched Web of Science and PubMed from inception through August 2021. We included studies measuring electrocardiogram (ECG) changes, laboratory abnormalities, or SCD among patients taking lamotrigine. Studies examining sudden unexpected death in epilepsy were excluded for scope. Two reviewers assessed articles and extracted data. We used the Effective Public Healthcare Panacea Project tool to evaluate confidence in evidence.

RESULTS

Eight randomized controlled trials, 9 nonrandomized observational studies, and 24 case reports were identified, with >3054 total participants, >1606 of whom used lamotrigine. One randomized trial of older patients found an average QRS increase of 3.5 +/- 13.1 ms. Fifteen studies reported no changes in ECG parameters. Case reports documented QRS widening (13), Brugada syndrome (6), QTc prolongation (1) and SCD (2), though many ingested toxic quantities of lamotrigine and/or other medications.

CONCLUSIONS

Evidence is insufficient to support the breadth of the FDA warning concerning lamotrigine's cardiac risk. Lamotrigine at therapeutic doses may be associated with modest, non-dangerous QRS widening.

Successful management of massive lamotrigine extended-release intoxication in a dog

A 3-year-old spayed female Siberian Husky presented for evaluation following ingestion of approximately 429 mg/kg of lamotrigine extended-release. She demonstrated severe neurologic and cardiac signs and was treated with lipid emulsion, anticonvulsants, antiarrhythmics and aggressive decontamination and supportive care. She was successfully discharged from the hospital 5 days later.

Lamotrigine Toxicosis Treated with Intravenous Lipid Emulsion Therapy in a Dog

A female spayed dachshund/mixed-breed dog was evaluated following ingestion of lamotrigine tablets with subsequent rapid onset of vomiting, diarrhea, and generalized tremoring. On initial examination, the dog was moderately obtunded and nonambulatory with intermittent myoclonus and hyperesthesia. Electrocardiogram revealed sinus tachycardia with prolongation of the QT interval. Intravenous lipid emulsion (ILE) infusion was initiated, with reduction in tremoring and improved patient mentation being noted after ∼20 min of therapy. An elevated cardiac troponin I value measured at 1.02 ng/mL the day after presentation. Serum toxicological assay revealed marked reduction in serum lamotrigine levels following ILE and continued reduction during hospitalization. The dog's clinical signs resolved, corrected QT interval returned to normal, and the patient was discharged 38 hr after presentation. Individual cases of lamotrigine toxicosis have not been fully reported in veterinary literature. This case report documents the rapid onset of clinical signs including neurologic dysfunction, cardiac arrhythmias, and transient corrected QT prolongation. Serial serum concentrations of lamotrigine showed a rapid reduction with ILE therapy and corresponded with clinical recovery, suggesting efficacy of ILE treatment in this case.

Massive lamotrigine and bupropion overdose resulting in status epilepticus without cardiovascular collapse

An 18 year-old woman presented to an outside hospital with seizure activity after a massive ingestion of lamotrigine, bupropion, trazodone, buspirone, and possibly isoretinoin. Her initial vital signs were remarkable for tachycardia (120 bpm). She was intubated for airway protection. For treatment of status epilepticus, she received a total of 12 mg of IV lorazepam along with a lorazepam infusion titrated to 15 mg/hr, a propofol infusion of unknown dosing, and phenobarbital 650 mg. She was transferred to a receiving hospital. Her initial ECG at the receiving hospital showed a QRS of 117 ms which narrowed with 50 mEq of sodium bicarbonate after approximately 6 hours. She required norepinephrine intermittently for blood pressure support for approximately 2 days. The patient had no dysrhythmias. EEG showed no epileptiform activity from approximately 11 hours–32 hours post ingestion. At the receiving hospital, her serum lamotrigine concentration was 109 mcg/mL (reference 3.0–14.0 mcg/mL) 7 hours after ingestion. Her bupropion concentration was 92 ng/mL (reference 50–100 ng/mL). She was extubated on hospital day 5 and discharged to a psychiatric facility on hospital day 13.

Literature review of the evidence regarding intravenous lipid administration in drug-induced cardiotoxicity

Introduction: Intravenous lipid emulsion (ILE) administration is capable of reversing the acute cardiac and neurological toxicity caused by local anesthetic agents. In recent years, ILE has also been explored as a potential antidote for cardiotoxicity caused by non-anesthetic agents too. Areas covered: The potential mechanisms, safety, and efficacy of this approach are considered. Data were sought from published reports listed in PubMed and EMBASE, and abstracts of meetings of the North American Congress of Clinical Toxicology and European Association of Poisons Centres and Clinical Toxicologists. There were reports involving 298 patients where ILE has been administered for severe drug toxicity. Clinical improvement was observed in 57 of 59 patients with local anesthetic toxicity (96.6%); there were 239 patients where toxicity was due to non-anesthetic agents, and ILE apparently improved clinical outcome in 215 (72.1%). Expert opinion: Response rates were similar between ILE treated toxicity caused by lipid soluble and non-lipid soluble drugs. Potential adverse effects of ILE include interference with laboratory assays, acute pancreatitis, and adult respiratory distress syndrome, although the rate of occurrence is difficult to ascertain.

Management of lamotrigine overdose using hemodialysis

Lamotrigine [LTG] is primarily an anti-epileptic drug used to treat seizure disorders, depression, and bipolar disease. It is generally well tolerated with limited side effects reported during routine use. Adverse events after overdose include neurotoxicity in the form of sedation and seizure activity, as well as cardiopulmonary toxicity in the form of sodium-channel blockade and cardiovascular collapse. There is no consensus regarding the role of hemodialysis (HD) in management of lamotrigine toxicity. Based on pharmacological properties, LTG is a candidate for extracorporeal removal, however, the successful use of HD for the treatment of this poisoning is not well described. We report the case of a 44 year-old female after a LTG overdose that experienced prolonged sedation that was ultimately treated with HD with an excellent response.

The use of intralipid emulsion therapy to treat severe cardiotoxicity secondary to lamotrigine ingestion in a dog

Lamotrigine is a sodium and calcium channel blocker, used to treat seizures in people. Dogs metabolize Lamotrigine to a cardiotoxic metabolite that causes severe, often fatal ventricular arrhythmias. This report documents the successful treatment of refractory Lamotrigine cardiotoxicity in a dog, using intralipid emulsion therapy.

The Mechanisms Underlying Lipid Resuscitation Therapy

The experimental use of lipid emulsion for local anesthetic toxicity was originally identified in 1998. It was then translated to clinical practice in 2006 and expanded to drugs other than local anesthetics in 2008. Our understanding of lipid resuscitation therapy has progressed considerably since the previous update from the American Society of Regional Anesthesia and Pain Medicine, and the scientific evidence has coalesced around specific discrete mechanisms. Intravenous lipid emulsion therapy provides a multimodal resuscitation benefit that includes both scavenging (eg, the lipid shuttle) and nonscavenging components. The intravascular lipid compartment scavenges drug from organs susceptible to toxicity and accelerates redistribution to organs where drug (eg, bupivacaine) is stored, detoxified, and later excreted. In addition, lipid exerts nonscavenging effects that include postconditioning (via activation of prosurvival kinases) along with cardiotonic and vasoconstrictive benefits. These effects protect tissue from ischemic damage and increase tissue perfusion during recovery from toxicity. Other mechanisms have diminished in favor based on lack of evidence; these include direct effects on channel currents (eg, calcium) and mass-effect overpowering a block in mitochondrial metabolism. In this narrative review, we discuss these proposed mechanisms and address questions left to answer in the field. Further work is needed, but the field has made considerable strides towards understanding the mechanisms.

Intravenous Lipid Emulsion as Antidote: Experience in Hong Kong

Objective

Intravenous lipid emulsion (ILE) is an emerging therapy in the field of toxicology. The purpose of this study was to report the accumulated local experience on using ILE in the management of patients suffering from poisoning by pharmaceutical agents other than local anaesthetics.

Design

Case series.

Setting

Local poison information centre.

Methods

Ten patients were identified from the database of Hong Kong Poison Information Centre. The patients were managed in 6 Hong Kong public hospitals during a 4-year study period (July 2008-June 2012).

Results

Nine of them presented with drug-induced cardiotoxicity, defined as either cardiac arrest (n=3) or hypotension refractory to other treatments (n=6). The overall survival rate is 30%. Possible adverse events from ILE included mild derangement of liver function, elevated amylase and hyperlipidaemia were observed.

Conclusions

About 30% of severe poison-induced cardiotoxicity treated with ILE can survive with no major adverse effects. The use of ILE remains to be a treatment option for lipid-soluble drug induced severe toxicity not responsive to standard resuscitation measures. (Hong Kong j. emerg.med. 2015;22:100-107)

Severe lamotrigine toxicosis in a dog

Objective

The objective of this study was to describe a case of severe lamotrigine toxicosis in a dog, which was successfully treated using minimal medical interventions.

Case summary

A 7-month-old male, intact, Labrador mix was evaluated because of acute onset of vomiting, rigidity, and dull mentation after ingesting lamotrigine tablets. The estimated oral dose that had been ingested was 278 mg/kg (611.6 mg/lb). Physical examination was unremarkable other than abnormalities noted in the cardiovascular and neurological systems. Neurological examination revealed dull mentation, vertical nystagmus, four-legged extensor limb rigidity, and alligator rolling. Cardiovascular examination revealed pale pink mucous membranes and multifocal ventricular tachycardia. Intravenous (IV) fluids were started at three times maintenance (180 mL/kg/day). Methocarbamol (100 mg/kg [220 mg/lb], rectally) and lidocaine (2 mg/kg [4.4 mg/lb, IV]) were administered. Twenty-four and seventy-two hours after presentation, the dog was clinically normal with no ventricular tachycardia being noted.

Conclusion

Lamotrigine (6-[2,3-dichlorophenyl]-1,2,4-triazine-3,5-diamine) is an anticonvulsant medication used in humans, which inhibits voltage-gated sodium channels. The clinical success of this case suggests that administration of only methocarbamol for the neurologic effects and lidocaine for the arrhythmias, as well as supportive IV fluid therapy, could be a successful treatment strategy for dogs, even with severe lamotrigine toxicosis.

Safety profile of lamotrigine in overdose

BACKGROUND

Lamotrigine is an anticonvulsant as well as a mood stabilizer. Apart from its established use in the treatment of epilepsy, there has been an expansion of its use in the treatment of mental disorders. Patients with epilepsy as well as those with mental disorders are at increased risk of deliberate drug overdoses. An evidence base for the safety profile of lamotrigine in overdose is an essential tool for prescribers. The objective of this study was to carry out a narrative synthesis of the existing evidence for the safety profile of lamotrigine in overdose.

METHODS

A systematic search was conducted of EMBASE (1974 to December 2015), MEDLINE (1946 to December 2015), PsycINFO (1806 to December 2015) and CINAHL (1981 to December 2015) databases. Studies were included in which there was a deliberate or accidental single drug overdose of lamotrigine, with its toxic effects described. Studies that did not involve an overdose were excluded. A narrative synthesis of the described toxic effects was carried out.

RESULTS

Out of 562 articles identified, 26 studies were included, mainly in the form of case reports and series. The most commonly described toxic effects of lamotrigine were on the central nervous system, specifically seizures, movement disorders and reduced consciousness. Other toxic effects included QTc interval and QRS complex prolongations, hypersensitivity reactions, serotonin syndrome as well as rhabdomyolysis possibly due to seizures and/or agitation. Deaths were recorded in two studies, with cardiovascular and neurological toxic effects described.

CONCLUSIONS

Even though lamotrigine has been reported to be well tolerated, there is a risk of toxic effects which can be life threatening in overdose. This needs to be borne in mind when prescribing to patients at an increased risk of deliberate drug overdose.

Intravenous Lipid Emulsion for Management of Systemic Toxic Effects of Drugs

The incidence of toxic effects of drugs leading to emergency department visits has increased in the United States in the past several years. Most of these patients can be adequately managed by supportive care alone. However, pharmacological antidotes may be necessary, particularly in patients with hemodynamic instability. In severe cases refractory to conventional antidote therapy, rescue therapy with intravenous lipid emulsion (ILE) may be necessary. Traditionally, ILE has been used as an antidote of choice in treating toxic effects of local anesthetics. But data continue to emerge on the successful use of ILE to treat overdoses of drugs other than local anesthetics, particularly lipophilic medications. The recommended ILE dose is a 1.5 mL/kg bolus followed by infusion of 15 mL/kg per hour, with repeat dosing permissible for continued hemodynamic instability. Use of ILE should be considered early as a rescue therapy in the settings of lipophilic medication overdoses when cardiovascular compromise or cardiac arrest is present.

Evolving Electrocardiographic Changes in Lamotrigine Overdose: A Case Report and Literature Review

Lamotrigine overdose usually follows a benign pattern, and the majority of cases reported involve a co-ingestant. Prior reports have suggested the possible use of intravenous lipid emulsion in cases of severe sodium channel blockade. We describe the electrocardiographic changes in a massive lamotrigine overdose treated with intravenous lipid emulsion. A 36-year-old male with bipolar disorder ingested 13.5 g of lamotrigine in a suicidal attempt. The lamotrigine level was 78.0 μg/mL. Comprehensive drug screen was negative for all screened compounds. The electrocardiogram demonstrated a prolonged QRS complex and signs suggestive of sodium channel blockade. Refractory to treatment with sodium bicarbonate was treated with intravenous lipid emulsion, with immediate resolution of the electrocardiographic changes. Lamotrigine inhibits the voltage-gated sodium channel opening, attenuating the release of excitatory neurotransmitters. Cardiac intraventricular conduction could be delayed in cases of lamotrigine overdose resulting in QRS and QTc prolongation and R waves >3 mm in leads I and aVR. A potential role for intravenous lipid emulsion therapy has been described in patients with toxic levels of lamotrigine and electrocardiographic changes refractory to the treatment with sodium bicarbonate. Intravenous lipid emulsion has been successfully used in the treatment of lamotrigine cardiac toxicity.

LIPAEMIC report: results of clinical use of intravenous lipid emulsion in drug toxicity reported to an online lipid registry

The use of intravenous lipid emulsion (ILE) as an antidote has prompted significant academic and clinical interest. Between August 2009 and August 2012, data from cases of ILE use in intoxicated patients in different hospitals on different continents were voluntarily entered into a registry based on the world wide web (www.lipidregistry.org). Here, we report data from this project. Participating centers were given access to the registry following institutional subscription. Specifically sought were details of the individual patients' presenting condition, indications for ILE use, ILE administration regimen, potential complications, and of clinical outcome. Forty-eight uses of ILE were reported from 61 participating centers. Ten cases of local anesthetic systemic toxicity were reported; all (10/10) survived. Thirty-eight cases of intoxication by other agents were reported [30 decreased conscious state, 8 cardiovascular collapse (3 deaths)]. There was an elevation in GCS (p < 0.0001) and increased systolic blood pressure (p = 0.012) from immediately prior to ILE administration to 30 min after use. One serious and two minor adverse effects of ILE use were recorded in 48 reported cases (one case of bronchospastic reaction, one case of hyperamylasemia and one case of interference with laboratory testing). In this series of cases reported to the registry, improvements were seen for GCS in patients with central nervous system toxicity and in systolic blood pressure in shocked patients over a short time frame after the injection of ILE. Few adverse effects were recorded. Clinical trials and the reporting of drug concentrations after ILE use are necessary to further elucidate the role of ILE in clinical toxicology.

Ventricular dysrhythmias associated with poisoning and drug overdose: a 10-year review of statewide poison control center data from California

BACKGROUND

Ventricular dysrhythmias are a serious consequence associated with drug overdose and chemical poisoning. The risk factors for the type of ventricular dysrhythmia and the outcomes by drug class are not well documented.

OBJECTIVE

The aim of this study was to determine the most common drugs and chemicals associated with ventricular dysrhythmias and their outcomes.

METHODS

We reviewed all human exposures reported to a statewide poison control system between 2002 and 2011 that had a documented ventricular dysrhythmia. Cases were differentiated into two groups by type of arrhythmia: (1) ventricular fibrillation and/or tachycardia (VT/VF); and (2) torsade de pointes (TdP).

RESULTS

Among the 300 potential cases identified, 148 cases met the inclusion criteria. Of these, 132 cases (89%) experienced an episode of VT or VF, while the remaining 16 cases (11%) had an episode of TdP. The most commonly involved therapeutic classes of drugs associated with VT/VF were antidepressants (33/132, 25%), stimulants (33/132, 25%), and diphenhydramine (16/132, 12.1%). Those associated with TdP were antidepressants (4/16, 25%), methadone (4/16, 25%), and antiarrhythmics (3/16, 18.75%). Drug exposures with the greatest risk of death in association with VT/VF were antidepressant exposure [odds ratio (OR) 1.71; 95% confidence interval (CI) 0.705-4.181] and antiarrhythmic exposure (OR 1.75; 95% CI 0.304-10.05), but neither association was statistically significant. Drug exposures with a statistically significant risk for TdP included methadone and antiarrhythmic drugs.

CONCLUSIONS

Antidepressants and stimulants were the most common drugs associated with ventricular dysrhythmias. Patients with suspected poisonings by medications with a high risk of ventricular dysrhythmia warrant prompt ECG monitoring.

Fusion of microlitre water-in-oil droplets for simple, fast and green chemical assays

Fusion of pipette-generated droplets in an oil matrix enables analyses using a minimum amount of equipment and reagents.

Lipid emulsion use precluding renal replacement therapy

BACKGROUND

Intralipid emulsion (ILE) is a nutritional fatty acid supplementation that is emerging as a potential therapy for local anesthetic systemic toxicity and is also being considered as a therapy for other lipophilic medication intoxications. Isolated reports of pulmonary edema or severe lipemia exist as a complication of therapy.

CASE REPORT

A 26-year-old hypertensive, male, kidney transplant recipient presented to an outside emergency department (ED) after an intentional overdose of his medications (ie, amlodipine, metoprolol, lisinopril). At presentation, he had hypotension and bradycardia that was unresponsive to treatment with intravenous saline, calcium, glucagon, and vasopressors. After failure of conventional therapy, an initial bolus of ILE (20%) was given with some improvement in his heart rate, and the dose was repeated. A continuous intravenous infusion of ILE therapy was started. The patient deteriorated, with development of both acute respiratory and renal failure. Continuous venovenous hemofiltration (CVVHF) was attempted to remove volume and correct metabolic abnormalities. Lipemic blood was immediately observed in the CVVHF filter. After 15 min, the transmembrane pressures of the filter began to rise in the absence of observed clotting of the blood and the filter then became completely obstructed. An attempt was made to remove the lipid by plasmapheresis to restart CVVHF, but the patient continued to deteriorate despite maximal vasopressor support. The patient's family decided to withdraw care and the patient expired. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Emergency physicians treat patients with toxic ingestions on a regular basis. Being aware of possible complications of experimental antidote therapy, like ILE, can improve the treatment approach and outcomes for these patients.

Toxicologic emergencies in the intensive care unit: management using reversal agents and antidotes

PURPOSE

To review the most common drugs implicated in overdoses admitted to the intensive care unit focusing on antidotes and reversal agents used in their management.

SUMMARY

Poisonings and overdoses due to pharmaceutical agents result in more than 100 000 critical care unit admissions each year. Ingestion of toxic alcohols, calcium channel blockers, beta-adrenergic antagonists, benzodiazepines, opioids, acetaminophen, tricyclic antidepressants, and salicylates are associated with a high rate of morbidity and mortality. Reviewing the mechanism of toxicity due to specific agents along with the mechanism of action, dosing, and adverse effects of appropriate antidotes is important for the successful management of these patients within the critical care unit.

CONCLUSION

Understanding the most prevalent overdoses and their management using reversal agents and antidotes is essential to the overall treatment of these critically ill patients.

Review of the use of lipid emulsion in nonlocal anesthetic poisoning

Intravenous lipid emulsion (ILE) has been used widely for the treatment of poisoning due to local anesthetic agent and is increasingly reported as a therapy for other forms of poisoning. This article will review the proposed mechanisms of action for ILE in poisoning and the evidence from animal studies and human experience supporting the use of ILE for poisoning due to nonlocal anesthetic agents.

Intravenous lipid emulsion alters the hemodynamic response to epinephrine in a rat model

Intravenous lipid emulsion (ILE) is an adjunctive antidote used in selected critically ill poisoned patients. These patients may also require administration of advanced cardiac life support (ACLS) drugs. Limited data is available to describe interactions of ILE with standard ACLS drugs, specifically epinephrine. Twenty rats with intra-arterial and intravenous access were sedated with isoflurane and split into ILE or normal saline (NS) pretreatment groups. All received epinephrine 15 μm/kg intravenously (IV). Continuous mean arterial pressure (MAP) and heart rate (HR) were monitored until both indices returned to baseline. Standardized t tests were used to compare peak MAP, time to peak MAP, maximum change in HR, time to maximum change in HR, and time to return to baseline MAP/HR. There was a significant difference (p = 0.023) in time to peak MAP in the ILE group (54 s, 95 % CI 44-64) versus the NS group (40 s, 95 % CI 32-48) and a significant difference (p = 0.004) in time to return to baseline MAP in ILE group (171 s, 95 % CI 148-194) versus NS group (130 s, 95 % CI 113-147). There were no significant differences in the peak change in MAP, peak change in HR, time to minimum HR, or time to return to baseline HR between groups. ILE-pretreated rats had a significant difference in MAP response to epinephrine; ILE delayed the peak effect and prolonged the duration of effect of epinephrine on MAP, but did not alter the peak increase in MAP or the HR response.

Resuscitation with lipid emulsion: dose-dependent recovery from cardiac pharmacotoxicity requires a cardiotonic effect

BACKGROUND

Recent publications have questioned the validity of the "lipid sink" theory of lipid resuscitation while others have identified sink-independent effects and posed alternative mechanisms such as hemodilution. To address these issues, the authors tested the dose-dependent response to intravenous lipid emulsion during reversal of bupivacaine-induced cardiovascular toxicity in vivo. Subsequently, the authors modeled the relative contribution of volume resuscitation, drug sequestration, inotropy and combined drug sequestration, and inotropy to this response with the use of an in silico model.

METHODS

Rats were surgically prepared to monitor cardiovascular metrics and deliver drugs. After catheterization and instrumentation, animals received a nonlethal dose of bupivacaine to produce transient cardiovascular toxicity, then were randomized to receive one of the four treatments: 30% intravenous lipid emulsion, 20% intravenous lipid emulsion, intravenous saline, or no treatment (n = 7 per condition; 28 total animals). Recovery responses were compared with the predictions of a pharmacokinetic-pharmacodynamic model parameterized using previously published laboratory data.

RESULTS

Rats treated with lipid emulsions recovered faster than did rats treated with saline or no treatment. Intravenous lipid emulsion of 30% elicited the fastest hemodynamic recovery followed in order by 20% intravenous lipid emulsion, saline, and no treatment. An increase in arterial blood pressure underlay the recovery in both lipid emulsion-treated groups. Heart rates remained depressed in all four groups throughout the observation period. Model predictions mirrored the experimental recovery, and the model that combined volume, sequestration, and inotropy predicted in vivo results most accurately.

CONCLUSION

Intravenous lipid emulsion accelerates cardiovascular recovery from bupivacaine toxicity in a dose-dependent manner, which is driven by a cardiotonic response that complements the previously reported sequestration effect.

Nutrition as medical therapy

Recent data support the use of nutritional agents for use as targeted medical therapy. This article reviews some of the pharmacologic roles that parenteral nutritional ingredients (selenium, lipid emulsion, insulin, and levocarnitine) can play in the setting of critical illness.

Intravenous lipid emulsion does not reverse dabigatran-induced anticoagulation in a rat model

OBJECTIVES

The anticoagulant dabigatran has no reversal agent and may cause life-threatening bleeding in patients with trauma or closed-space hemorrhage. Intravenous lipid emulsion (ILE) is thought to create a lipid compartment in serum that sequesters lipophilic drugs. Dabigatran is lipophilic, and its anticoagulant effects are concentration dependent. The study objective was to determine if ILE therapy reverses dabigatran's anticoagulant effects.

METHODS

Twenty rats were selected at random, 10 in the ILE group and 10 in a normal saline (NS) control group. Animals had a baseline tail bleeding time (T0), followed by oral dabigatran administration (15 mg/kg). At 45 minutes (T45), a second tail bleed time measurement was performed, followed by a 7-minute infusion of 15 mL/kg ILE or NS. A final 60-minute (T60) bleed time measurement was obtained. An ILE-only group of five animals had bleeding times assessed prior to (T0) and 15 minutes after (T15) ILE therapy. A mixed-effect repeated-measures analysis of variance modeling the effect of time, group, and the interaction of group and time on bleed times was conducted.

RESULTS

There was a significant within-subject change in bleeding time across the assessment points (F(2,36) = 33; p < 0.001), but there were no effect of group (F(1,18) = 1.42, p = 0.25) or an interaction between group and assessment point on mean bleeding time (F(2,36) = 0.59, p = 56). Between T0 and T45, average bleeding times increased from 109.5 seconds (95% confidence interval [CI] = 94 to 125 seconds) to 231.8 seconds (95% CI = 193 to 271 seconds; p < 0.0001) for both the ILE group and the NS control group. Between T45 and T60, bleeding times in the ILE group decreased by 31.5 seconds (95% CI = -77 to 14 seconds) and by 6 seconds (95% CI = -67 to 55 seconds) in the NS group (p = 0.46). In the five ILE-only animals, the average bleeding time at T0 was 114 seconds (95% CI = 62 to 166 seconds), which increased significantly at T15 to 237 seconds (95% CI = 161 to 313 seconds; p = 0.02).

CONCLUSIONS

The anticoagulant effects of dabigatran are not reversed with ILE therapy. Although ILE itself significantly prolonged bleeding times, when administered to dabigatran-anticoagulated rats, bleeding times did not change significantly. There may be a complex interaction of ILE with dabigatran that this study was not able to elucidate.

A case series of patients with lamotrigine toxicity at one center from 2003 to 2012

INTRODUCTION

Lamotrigine is a phenyltriazine compound that inhibits voltage-gated sodium channels, decreasing release of glutamate and aspartate, and inhibits serotonin, norepinephrine and dopamine reuptake. Reports of toxicity in the literature are limited to case reports and primarily involve coingestants. This case series is intended to report the clinical manifestations of lamotrigine toxicity.

METHODS

This retrospective case series from 2003 to 2012 studies the effects of lamotrigine toxicity when not confounded by coingestants. Admission records at an inpatient toxicology center were reviewed for lamotrigine-only exposure based on history with supporting laboratory data when available. After identification, these charts were reviewed again to characterize vital signs, neurological examination findings, specific laboratory and electrocardiography parameters, and complications.

RESULTS

Fifty-seven patients were identified with possible lamotrigine toxicity. Nine patients, including three toddlers, had lamotrigine-only ingestions. Three of these patients had seizures, four were hypertensive, five were tachycardic, and four experienced tachypnea. Mental status was altered in all nine (depressed (n = 4), agitated (n = 5) or both (n = 3)). Five patients were hyperreflexic and experienced intermittent myoclonus, and two had inducible clonus. On electrocardiogram, two patients experienced QRS prolongation (114-116 ms), and four had QTc prolongation (463-586 ms). No patient had life-threatening symptoms or signs. Serum levels of lamotrigine were available in seven patients, and averaged 35.4 mg/L (17-90 mg/L). The therapeutic range for sLTG is 3-14 mg/L.

CONCLUSIONS

Lamotrigine toxicity manifested with minor-moderate neurologic and/or electrocardiographic effects. Toxicity reflects the known pharmacologic actions of lamotrigine: serotonin, norepinephrine and dopamine reuptake inhibition, and sodium channel blockade.

Intravenous lipid administration for drug-induced toxicity: a critical review of the existing data

Following the discovery that administration of intravenous lipid emulsion (ILE) may reverse the cardiac and neurological toxicity of certain local anesthetic agents, ILE's potential role has recently been explored in the setting of toxicity attributed to a variety of different drugs. The potential mechanisms, safety and efficacy of this approach are considered in this review. Data are reviewed from 76 published reports involving ILE administration for severe drug toxicity, including 55 where toxicity was due to nonanesthetic agents. ILE was reported to exert a positive therapeutic effect in only a proportion of the reported cases, with greatest evidence of efficacy concerning local anesthetic agents. Administration has typically involved bolus administration followed by continuous maintenance infusion, and a number of different mechanisms are proposed, from preferential partitioning of the drug from cardiac tissue to the circulating lipid fraction and direct inotropic effects related to carnitine pathways and fatty acid oxidative metabolism. No major adverse effects have been encountered, but too few data exist to adequately address the safety profile of ILE.