Salicylate intoxication: a clinical review

Molecular and behavioral effects of Acamprosate in male rats with sodium salicylate-induced tinnitus

BACKGROUND

Imbalance in inhibitory and excitatory neurotransmitters have been reported in tinnitus. Acamprosate modulates the excitatory and inhibitory neurotransmission in the nucleus accumbens (NAc). This study aims to assess the effect of Acamprosate on tinnitus, anxiety, depression, and molecular changes in nucleus accumbens (NAc), in Sodium-Salisylate (S-salicylate) model of tinnitus.

METHODS

Forty-four adult male wistar rats were used in this study. The study included Control, Saline, and S-salicylate groups during the first week, which then subdivided into five groups as Control, Saline, S-salicylate, Acamprosate, and S-salicylate+Acamprosate. Gap-in Noise (GIN) and pre-pulse inhibition (PPI) were used to assessment of tinnitus at baseline, day7 and day14. Anxiety and depression were evaluated on day 14, by elevated plus maze (EPM), open field (OF), and tail suspension (TST) tests. The protein expression of GABAAR-δ, NR1 and NR2B in NAc were also measured using western blot technique.

RESULTS

After seven days GIN reduced in S-salicylate compare to Control and Saline groups (P < 0.5), while PPI unchanged. After 14 days, GIN reduced in S-salicylate and S-salicylate+Acamprosate groups compare to Control; Saline; and Acamprosate groups (P < 0.5). Additionally, GIN was higher in S-salicylate+Acamprosate compare to S-salicylate group (P < 0.5). PPI was not changed after 14 days. Open arm time in EPM test was decreased in S-salicylate and S-salicylate+Acamprosate groups compare to Control; Saline; and Acamprosate groups (P < 0.5). Central Zone time in OF test was reduced in S-salicylate group compare to Control, Saline, Acamprosate, and S-salicylate+Acamprosate groups (P < 0.5). Immobility Time in TST was increased in S-salicylate group compare to Control, Saline, Acamprosate, and S-salicylate+Acamprosate groups (P < 0.5). GABAAR-δ was decreased in S-salicylate groups compare to Control, Saline, Acamprosate; and S-salicylate+Acamprosate groups (P < 0.5). NR1 and NR2B in NAc were increased in S-salicylate group compare to Control, Saline, Acamprosate, and S-salicylate+Acamprosate groups (P < 0.5).

CONCLUSION

S-salicylate can induce tinnitus-like behaviors in rat. Furthermore, S-salicylate induced depression/anxiety like behaviors, and changed the expression of GABAR and NMDAR subunits in NAc. Acamprosate partially reversed these changes. In conclusion, NAc may be involved in the pathophysiologic mechanisms of tinnitus.

The trajectory of serum salicylate concentrations after ingestion of medicinal oil containing methyl salicylate

INTRODUCTION

The toxicokinetics of methyl salicylate after unintentional or intentional ingestion of medicinal oil containing methyl salicylate has not been well studied. We aimed to characterize the trajectory of serum salicylate concentrations and to evaluate factors associated with the peak serum salicylate concentration and the time from ingestion to peak concentration.

METHODS

This was a retrospective cohort study of consecutive patients reported to the Hong Kong Poison Control Centre for laboratory-confirmed methyl salicylate poisoning by all local public emergency departments between 1 July 2008 and 30 June 2023. We analyzed cases with at least three serum salicylate concentrations. Multivariable generalized linear regression was used to identify factors significantly associated with the peak serum concentration and the time from ingestion to peak concentration.

RESULTS

We included 41 patients (median age 81.0 years; 32 women and nine men). The median time from ingestion to the first peak serum salicylate concentration was 5.6 h (IQR: 3.2-10.8 h). Multiple regression showed that gastric aspiration (adjusted regression coefficient [β] - 2.50; 95% CI: -3.93 to -1.08; P = 0.001) and single-dose activated charcoal (adjusted β - 1.22; 95% CI: -2.02 to -0.42; P = 0.003) were significantly associated with a lower peak concentration, after adjusting for patient age, sex, exposure due to intentional self-harm, reported ingested dose, time from ingestion to emergency department presentation, vomiting, concurrent use of aspirin (acetylsalicylic acid) and other medications that affect gastric emptying or gastric acid secretion, blood pH, serum albumin concentration, and creatinine clearance.

DISCUSSION

The serum salicylate concentration did not peak as quickly as generally believed, highlighting the importance of continued monitoring. Gastric aspiration and single-dose activated charcoal may help reduce gastrointestinal absorption, but their impact on clinical outcomes remains unclear.

CONCLUSIONS

Given the median time of 5.6 h (IQR: 3.2-10.8 h) from ingestion to the peak salicylate concentration, gastric aspiration and single-dose activated charcoal can be considered in patients up to a few hours after medicinal oil ingestion when the airway is protected.

Pharmacokinetics of aspirin: evaluating shortcomings in the literature

INTRODUCTION

Aspirin is known for its therapeutic benefits in preventing strokes and relieving pain. However, it is toxic to some individuals, and the biological mechanisms causing toxicity are unknown. Limited literature is available on the role of glycine conjugation as the principal pathway in aspirin detoxification. Previous studies have quantified this two-step enzyme reaction as a singular enzymatic process. Consequently, the individual contributions of these enzymes to the kinetics remain unclear.

AREAS COVERED

This review summarized the available information on the pharmacokinetics and detoxification of aspirin by the glycine conjugation pathway. Literature searches were conducted using Google Scholar and the academic journal databases accessible through the North-West University Library. Furthermore, the factors affecting interindividual variation in aspirin metabolism and what is known regarding aspirin toxicity were discussed.

EXPERT OPINION

The greatest drawback in understanding the pharmacokinetics of aspirin is the limited information available on the substrate preference of the xenobiotic ligase (ACSM) responsible for activating salicylate to salicyl-CoA. Furthermore, previous pharmacokinetic studies did not consider the contribution of other substrates from the diet or genetic variants, to the detoxification rate of glycine conjugation. Impaired glycine conjugation might contribute to adverse health effects seen in Reye's syndrome and cancer.

Metabolic, toxicological, chemical, and commercial perspectives on esterification of dietary polyphenols: a review

Molecular modifications have been practiced for more than a century and nowadays they are widely applied in food, pharmaceutical, or other industries to manipulate the physicochemical, bioactivity, metabolic/catabolic, and pharmacokinetic properties. Among various structural modifications, the esterification/O-acylation has been well-established in altering lipophilicity and bioactivity of parent bioactive compounds, especially natural polyphenolics, while maintaining their high biocompatibility. Meanwhile, various classic chemical and enzymatic protocols and other recently emerged cell factory technology are being employed as viable esterification strategies. In this contribution, the main motivations of phenolic esterification, including the tendency to replace synthetic alkyl phenolics with safer alternatives in the food industry to improve the bioavailability of phenolics as dietary supplements/pharmaceuticals, are discussed. In addition, the toxicity, metabolism, and commercial application of synthetic and natural phenolics are briefly introduced. Under these contexts, the mechanisms and reaction features of several most prevalent chemical and enzymatic esterification pathways are demonstrated. In addition, insights into the studies of esterification modification of natural phenolic compounds and specific pros/cons of various reaction systems with regard to their practical application are provided.

Validation of a simple spectrophotometric method for the rapid determination of salicylates in plasma

INTRODUCTION

The determination of salicylate concentrations constitutes a critical aspect of medical diagnostics, particularly in emergency settings. High-performance liquid chromatography (HPLC) and spectrophotometry are efficient methods commonly utilized for this purpose. In emergency laboratories with limited resources, the validation of a cost-effective and reliable spectrophotometric method for salicylates in plasma becomes imperative. The present study aims to validate such a method, ensuring its applicability in toxicological emergencies within resource-constrained laboratories.

MATERIALS AND METHODS

The proposed spectrophotometric analysis relies on detecting salicylic ions amidst the presence of ferric salts, resulting in the formation of a distinct purple chelate complex. To ascertain the method's credibility, the validation guidelines established by the European Medicines Agency (EMA) were employed as a benchmark. A comprehensive validation process was conducted over a three-day period, with three levels of validation standards being considered.

RESULTS

Following the EMA protocol, the spectrophotometric method demonstrated commendable fidelity, accuracy, and linearity over a concentration range of 50 to 500 mg/L. The limit of detection and quantification was found to be 10 and 50 mg/L, respectively, and the correlation coefficient was determined to be R2 = 0.998. However, it is essential to acknowledge that interference with phenothiazines occurred at concentrations ranging from 50 to 100 mg/L. Despite this, the method's average sensitivity remains viable for practical use in cases of poisoning. The accuracy per concentration level proved satisfactory, with relative biases remaining below 15%, and the confidence intervals of mean recovery closely approximating the desired target value of 100%.

CONCLUSION

In conclusion, the presented spectrophotometric method stands out as an economical, straightforward, and user-friendly approach, ideally suited for toxicological emergencies when resources are limited. The method delivers satisfying results, establishing its practical utility in critical medical scenarios. This validated method holds immense promise for emergency laboratories facing resource constraints.

Targeting Pseudomonas aeruginosa quorum sensing with sodium salicylate modulates immune responses in vitro and in vivo

Introduction

Chronic infections are a major clinical challenge in hard-to-heal wounds and implanted devices. Pseudomonas aeruginosa is a common causative pathogen that produces numerous virulence factors. Due to the increasing problem of antibiotic resistance, new alternative treatment strategies are needed. Quorum sensing (QS) is a bacterial communication system that regulates virulence and dampens inflammation, promoting bacterial survival. QS inhibition is a potent strategy to reduce bacterial virulence and alleviate the negative impact on host immune response.

Aim

This study investigates how secreted factors from P. aeruginosa PAO1, cultured in the presence or absence of the QS inhibitor sodium salicylate (NaSa), influence host immune response.

Material and methods

In vitro, THP-1 macrophages and neutrophil-like HL-60 cells were used. In vivo, discs of titanium were implanted in a subcutaneous rat model with local administration of P. aeruginosa culture supernatants. The host immune response to virulence factors contained in culture supernatants (+/-NaSa) was characterized through cell viability, migration, phagocytosis, gene expression, cytokine secretion, and histology.

Results

In vitro, P. aeruginosa supernatants from NaSa-containing cultures significantly increased THP-1 phagocytosis and HL-60 cell migration compared with untreated supernatants (-NaSa). Stimulation with NaSa-treated supernatants in vivo resulted in: (i) significantly increased immune cell infiltration and cell attachment to titanium discs; (ii) increased gene expression of IL-8, IL-10, ARG1, and iNOS, and (iii) increased GRO-α protein secretion and decreased IL-1β, IL-6, and IL-1α secretion, as compared with untreated supernatants.

Conclusion

In conclusion, treating P. aeruginosa with NaSa reduces the production of virulence factors and modulates major immune events, such as promoting phagocytosis and cell migration, and decreasing the secretion of several pro-inflammatory cytokines.

Prediction rule of supratherapeutic peak serum salicylate level in poisoning patients attending emergency departments

Background:

Analgesic poisoning is common in Hong Kong. Analgesics containing salicylate are easily available. Salicylate poisoning may be encountered in the daily practice of the accident and emergency department. The issue of routine salicylate screening was discussed in a number of articles, and the viewpoints of most authors were that routine salicylate screening was unnecessary.

Objectives:

The primary outcome is to explore the predictive factors of supratherapeutic peak serum salicylate level (>2.17 mmol/L) and delineate the role of routine screening serum salicylate level in poisoned patients attending the accident and emergency department.

Methods:

This is a retrospective cohort study. Poisoning cases presented to Hong Kong Poison Information Centre between 1 July 2008 and 31 October 2020 with serum salicylate level checked were included. The demographics, laboratory parameters and clinical outcomes were reviewed.

Results:

There were 8673 cases included with serum salicylate level checked, accounting for 17% of all poisoning cases. Sixty-six (0.76%) cases had supratherapeutic peak serum salicylate level and 11 (0.13%) of them were undeclared salicylate ingestion. Worse clinical outcomes were observed in cases with supratherapeutic peak serum salicylate level. Univariate analysis showed that tinnitus, hyperthermia, alkalaemia, metabolic acidosis, respiratory alkalosis and therapeutic use of aspirin were significantly associated with supratherapeutic peak serum salicylate level. Variables with p < 0.3 were entered into the backward stepwise logistic regression by likelihood ratio. A clinical prediction rule with three attributes (tinnitus, therapeutic use of aspirin and partial pressure of CO2 <5 kPa) was derived. It showed 100% sensitivity in internal validation.

Conclusion:

Serum salicylate level should be checked in poisoned patients with (1) tinnitus, (2) the therapeutic use of aspirin or (3) partial pressure of CO2 <5 kPa in arterial or venous blood gas. Routine salicylate screening remained a tool for clinicians not experienced in toxicology.

Principles of dose-setting in toxicology studies: the importance of kinetics for ensuring human safety

Regulatory toxicology seeks to ensure that exposures to chemicals encountered in the environment, in the workplace, or in products pose no significant hazards and produce no harm to humans or other organisms, i.e., that chemicals are used safely. The most practical and direct means of ensuring that hazards and harms are avoided is to identify the doses and conditions under which chemical toxicity does not occur so that chemical concentrations and exposures can be appropriately limited. Modern advancements in pharmacology and toxicology have revealed that the rates and mechanisms by which organisms absorb, distribute, metabolize and eliminate chemicals-i.e., the field of kinetics-often determine the doses and conditions under which hazard, and harm, are absent, i.e., the safe dose range. Since kinetics, like chemical hazard and toxicity, are extensive properties that depend on the amount of the chemical encountered, it is possible to identify the maximum dose under which organisms can efficiently metabolize and eliminate the chemicals to which they are exposed, a dose that has been referred to as the kinetic maximum dose, or KMD. This review explains the rationale that compels regulatory toxicology to embrace the advancements made possible by kinetics, why understanding the kinetic relationship between the blood level produced and the administered dose of a chemical is essential for identifying the safe dose range, and why dose-setting in regulatory toxicology studies should be informed by estimates of the KMD rather than rely on the flawed concept of maximum-tolerated toxic dose, or MTD.

Systematic Review and Meta-Analyses Assessment of the Clinical Efficacy of Bismuth Subsalicylate for Prevention and Treatment of Infectious Diarrhea

BACKGROUND

A large number of studies have evaluated the pharmacology, safety, and/or efficacy of bismuth subsalicylate for the relief of common gastrointestinal symptoms, diarrhea and vomiting due to acute gastroenteritis. In addition, short-term (48 h) medication with bismuth subsalicylate is known to be effective against infectious gastroenteritis such as travelers' diarrhea.

AIMS

Previous studies have documented the bacteriostatic/bactericidal effects of bismuth subsalicylate against a variety of pathogenic gastrointestinal bacteria. However, meta-analyses of the clinical efficacy of bismuth subsalicylate for both prevention and treatment of travelers' diarrhea have not yet been published.

METHODS

A total of 14 clinical studies (from 1970s to 2007) comprised the core data used in this assessment of efficacy of bismuth subsalicylate against infectious (including travelers') diarrhea. These studies allowed for statistical meta-analyses regarding prevention (three travelers' diarrhea studies) and treatment of infectious diarrhea (11 studies [five travelers' diarrhea]).

RESULTS

The results show that subjects treated with bismuth subsalicylate for up to 21 days have 3.5 times greater odds of preventing travelers' diarrhea compared with placebo (95% CI 2.1, 5.9; p < 0.001). In addition, subjects with infectious diarrhea treated with bismuth subsalicylate had 3.7 times greater odds of diarrhea relief (recorded on diaries as subjective symptomatic improvement) compared to those receiving placebo (95% CI 2.1, 6.3; p < 0.001).

CONCLUSIONS

This systematic review and meta-analysis suggests that bismuth subsalicylate can be beneficial for those at risk or affected by food and waterborne diarrheal disease such as traveler's (infectious) diarrhea, and may decrease the risk of inappropriate antibiotic utilization.

Rhabdomyolysis among hospitalized patients for salicylate intoxication in the United States: Nationwide inpatient sample 2003-2014

Introduction

This study aimed to assess the risk factors and impact of rhabdomyolysis on treatments, outcomes, and resource utilization in hospitalized patients for salicylate intoxication in the United States.

Materials and methods

The National Inpatient Sample was utilized to identify hospitalized patients with a primary diagnosis of salicylate intoxication from 2003–2014. Rhabdomyolysis was identified using hospital diagnosis code. We compared the clinical characteristics, in-hospital treatment, outcomes, and resource utilization between patients with and without rhabdomyolysis.

Results

A total of 13,805 hospital admissions for salicylate intoxication were studied. Of these, rhabdomyolysis developed in 258 (1.9%) admissions. The risk factors for rhabdomyolysis were age>20 years, male sex, volume depletion, hypokalemia, sepsis, and seizure. After adjustment for baseline clinical characteristics, salicylate intoxication patients with rhabdomyolysis required more invasive mechanical ventilation, and renal replacement therapy. Rhabdomyolysis was significantly associated with higher risk of failure of any organ systems, and in-hospital mortality. Length of hospital stay and hospitalization cost were higher when rhabdomyolysis occurred during hospital stay.

Conclusions

Rhabdomyolysis was not common in hospitalized patients for salicylate intoxication but it was associated with increased morbidity, mortality, and resource utilization.

Acute kidney injury among salicylate intoxication hospitalisations in the United States

BACKGROUND

This study aimed to evaluate the risk factors and the association of acute kidney injury (AKI) with outcomes, and resource utilisation in patients hospitalised because of salicylate intoxication in the United States.

METHODS

Hospitalised patients with a primary diagnosis of salicylate intoxication from 2003 to 2014 were identified in the National Inpatient Sample (NIS) database. End-stage kidney disease patients were excluded. The occurrence of AKI was identified using hospital diagnosis code. Clinical characteristics, in-hospital treatment, outcomes and resource utilisation were compared between patients with and without AKI.

RESULTS

A total of 13 787 eligible hospital admissions were included in the analysis. AKI occurred in 1279 (9.3%) admissions. Older age, male sex, more recent year of hospitalisation, anaemia, hypertension, congestive heart failure, chronic kidney disease, volume depletion, sepsis and ventricular arrhythmia/cardiac arrest were significantly associated with increased risk of AKI, whereas Hispanic race was associated with decreased risk. AKI was significantly associated with increased risk of organ failure, and in-hospital mortality. In addition, the need for ventilation support, blood component transfusion, renal replacement therapy, length of hospital stay and hospitalisation cost were higher in AKI patients.

CONCLUSION

Approximately one tenth of salicylate intoxication patients developed AKI during hospitalisation. AKI was associated with higher morbidity, mortality and resource utilisations.

Circulatory Shock among Hospitalized Patients for Salicylate Intoxication

BACKGROUND

This study aimed to evaluate the risk factors for circulatory shock and its impact on outcomes in patients hospitalized for salicylate intoxication.

METHODS

We used the National Inpatient Sample to identify patients hospitalized primarily for salicylate intoxication from 2003-2014. Circulatory shock was identified based on hospital diagnosis code for any type of shock or hypotension. We compared clinical characteristics, in-hospital treatments, outcomes, and resource use between patients with and without circulatory shock associated with salicylate intoxication.

RESULTS

Of 13,805 hospital admissions for salicylate intoxication, circulatory shock developed in 484 (4%) admissions. Risk factors for development of circulatory shock included older age, female sex, concurrent psychotropic medication overdose, anemia, congestive heart failure, volume depletion, rhabdomyolysis, seizure, gastrointestinal bleeding, and sepsis. Circulatory shock was significantly associated with increased odds of any organ failure and in-hospital mortality. Length of hospital stay and hospitalization cost was significantly higher in patients with circulatory shock.

CONCLUSION

Approximately 4% of patients admitted for salicylate intoxication developed circulatory shock. Circulatory shock was associated with worse clinical outcomes and increased resource use.

Salicylate toxicity from chronic bismuth subsalicylate use

A 79-year-old man presented to the emergency department with a 1-week history of worsening confusion, falls and hearing impairment. An initial workup for infectious, metabolic and structural causes was unrevealing. However, further history discovered that he had been ingesting one to two bottles of Pepto-Bismol (bismuth subsalicylate) daily for gastro-oesophageal reflux symptoms. On his second day of admission, the plasma salicylate concentration was 2.08 mmol/L (reference range 1.10-2.20 mmol/L), despite no sources of salicylate in hospital. He was diagnosed with chronic salicylate toxicity and Pepto-Bismol use was discontinued. The patient was treated supportively with isotonic intravenous fluids only and plasma salicylate concentration fell to less than 0.36 mmol/L. Concurrently, all his symptoms resolved. This case highlights the potential adverse effects of over-the-counter medications. The diagnosis of chronic salicylate toxicity is challenging, specifically in the elderly and in undifferentiated presentations, as it can be missed if not suspected.

Hospitalizations for Acute Salicylate Intoxication in the United States

Background: The objective of this study was to describe inpatient prevalence, characteristics, outcomes, and resource use for acute salicylate intoxication hospitalizations in the United States. Methods: A total of 13,805 admissions with a primary diagnosis of salicylate intoxication from 2003 to 2014 in the National Inpatient Sample database were analyzed. Prognostic factors for in-hospital mortality were determined using multivariable logistic regression. Results: The overall inpatient prevalence of salicylate intoxication among hospitalized patients was 147.8 cases per 1,000,000 admissions in the United States. The average age was 34 ± 19 years. Of these, 35.0% were male and 65.4% used salicylate for suicidal attempts. Overall, 6% required renal replacement therapy. The most common complications of salicylate intoxication were electrolyte and acid-base disorders, including hypokalemia (25.4%), acidosis (19.1%), and alkalosis (11.1%). Kidney failure (9.3%) was the most common observed organ dysfunction. In-hospital mortality was 1.0%. Increased in-hospital mortality was associated with age ≥30, Asian/Pacific Islander race, diabetes mellitus, hyponatremia, ventricular arrhythmia, kidney failure, respiratory failure, and neurological failure, while decreased in-hospital mortality was associated with African American and Hispanic race. Conclusion: hospitalization for salicylate intoxication occurred in 148 per 1,000,000 admissions in the United States. Several factors were associated with in-hospital mortality.

Anxiety-like behavior induced by salicylate depends on age and can be prevented by a single dose of 5-MeO-DMT

Salicylate intoxication is a cause of tinnitus and comorbidly associated with anxiety in humans. In a previous work, we showed that salicylate induces anxiety-like behavior and hippocampal type 2 theta oscillations (theta2) in mice. Here we investigate if the anxiogenic effect of salicylate is dependent on age and previous tinnitus experience. We also tested whether a single dose of DMT can prevent this effect. Using microwire electrode arrays, we recorded local field potential in young (4-5- month-old) and old (11-13-month-old) mice to study the electrophysiological effect of tinnitus in the ventral hippocampus (vHipp) and medial prefrontal cortex (mPFC) in an open field arena and elevated plus maze 1h after salicylate (300mg/kg) injection. We found that anxiety-like behavior and increase in theta2 oscillations (4-6 Hz), following salicylate pre-treatment, only occurs in young (normal hearing) mice. We also show that theta2 and slow gamma oscillations increase in the vHipp and mPFC in a complementary manner during anxiety tests in the presence of salicylate. Finally, we show that pre-treating mice with a single dose of the hallucinogenic 5-MeO-DMT prevents anxiety-like behavior and the increase in theta2 and slow gamma oscillations after salicylate injection in normal hearing young mice. This work further support the hypothesis that anxiety-like behavior after salicylate injection is triggered by tinnitus and require normal hearing. Moreover, our results show that hallucinogenic compounds can be effective in treating tinnitus-related anxiety.

Common Toxidromes and the Role of Extracorporeal Detoxification

Extracorporeal modalities have been used for detoxification for decades, with hemodialysis the preferred and most commonly used modality. Salicylates, lithium, methanol, and ethylene glycol are the most common poisonings treated with dialysis. For each of these common poisonings, a description of the toxidrome including pharmacokinetics, clinical presentation, an overview of treatment, and the role and application of dialysis is outlined. Inhibition of alcohol dehydrogenase to prevent the formation of toxic metabolites in methanol and ethylene glycol is discussed in detail, including the use of fomepizole and ethanol to complement and in some cases prevent the need for hemodialysis. Hemodialysis has been attempted to treat many poisonings, often without success. A description of EXTRIP (Extracorporeal Treatments in Poisoning), a multidisciplinary project examining the evidence for extracorporeal treatments in poisoning, is also described. Recommendations for poisoning with acetaminophen, baclofen, barbiturates, carbamazepine, digoxin, metformin, phenytoin, thallium, theophylline, tricyclic antidepressants, and valproic acid are provided in a comprehensive table.

Intentional acetylsalicylic acid acute intoxication and its clinical management

In the last decade, our knowledge about OTC drug intoxication has been expanded much further relative to previous years, though the absence of antidotes in some cases results in healthcare professionals using symptomatic treatment. This case report reminds the reader of the importance of clinical and toxicology laboratories in the management of acute salicylate intoxication in order to avoid hemodialysis.

Salicylate induces anxiety-like behavior and slow theta oscillation and abolishes the relationship between running speed and fast theta oscillation frequency

Salicylate intoxication is a cause of tinnitus in humans and it is often used to produce tinnitus-like perception in animal models. Here, we assess whether salicylate induces anxiety-like electrophysiological and behavioral signs. Using microwire electrode arrays, we recorded local field potential in the ventral and, in some experiments dorsal hippocampus, in an open field arena 1 hr after salicylate (300 mg/kg) injection. We found that animals treated with salicylate moved dramatically less than saline treated animals. Salicylate-treated animals showed a strong 4-6 Hz (type 2) oscillation in the ventral hippocampus (with smaller peaks in dorsal hippocampus electrodes). Coherence in the 4-6 Hz-theta band was low in the ventral and dorsal hippocampus when compared to movement-related theta coherence (7-10 Hz). Moreover, movement related theta oscillation frequency decreased and its dependency on running speed was abolished. Our results suggest that salicylate-induced theta is mostly restricted to the ventral hippocampus. Slow theta has been classically associated to anxiety-like behaviors. Here, we show that salicylate application can consistently generate low frequency theta in the ventral hippocampus. Tinnitus and anxiety show strong comorbidity and the increase in ventral hippocampus low frequency theta could be part of this association.

Acute respiratory distress syndrome caused by salicylate intoxication

Salicylate-induced acute respiratory syndrome (ARDS) is a well-known entity occurring in 35% of salicylate-intoxicated patient. Careful history taking, physical examination, arterial blood gas analysis, and measurement of serum salicylate concentration will lead to early recognition to initiate appropriate treatment.

Unusual cause of encephalopathy after brain surgery

For patients who have had a recent neurosurgical procedure, a visit to the emergency department for encephalopathy may automatically prompt a neurosurgical consult. We present a case of a patient with a history of Chiari malformation decompressed 6 months prior who presented with a 2-week history of slowly progressive altered mental status, headache and imbalance-symptoms consistent with her initial Chiari symptoms, so neurosurgery was consulted. Imaging showed no acute abnormality, but laboratory results revealed metabolic acidosis with high salicylate levels. When reporting medication use, this patient initially left out that she had been taking Goody's powder (845 mg aspirin) for headaches, and long-term use led to metabolic encephalopathy. Despite a recent history of surgery, it is important to keep the differential diagnosis broad especially when there are signs of metabolic derangement.

Fatal Ingestion of Chlumsky Disinfectant Solution

A 32-year-old pregnant woman in the 25th week of pregnancy underwent oral glucose tolerance screening at the diabetologist's. Later that day, she was found dead in her apartment possibly poisoned with Chlumsky disinfectant solution (solutio phenoli camphorata). An autopsy revealed chemical burns in the digestive system. The lungs and the brain showed signs of severe edema. The blood of the woman and fetus was analyzed using gas chromatography with mass spectrometry and revealed phenol, its metabolites (phenyl glucuronide and phenyl sulfate) and camphor. No ethanol was found in the blood samples. Both phenol and camphor are contained in Chlumsky disinfectant solution, which is used for disinfecting surgical equipment in healthcare facilities. Further investigation revealed that the deceased woman had been accidentally administered a disinfectant instead of a glucose solution by the nurse, which resulted in acute intoxication followed by the death of the pregnant woman and the fetus.

Acute salicylate poisoning: risk factors for severe outcome

CONTEXT

Salicylate poisoning remains a significant public health threat with more than 20,000 exposures reported annually in the United States.

OBJECTIVE

We aimed to establish early predictors of severe in-hospital outcomes in Emergency Department patients presenting with acute salicylate poisoning.

METHODS

This was a secondary data analysis of adult salicylate overdoses from a prospective cohort study of acute drug overdoses at two urban university teaching hospitals from 2009 to 2013. Patients were included based on confirmed salicylate ingestion and enrolled consecutively. Demographics, clinical parameters, treatment and disposition were collected from the medical record. Severe outcome was defined as a composite occurrence of acidemia (pH <7.3 or bicarbonate <16 mEq/L), hemodialysis, and/or death.

RESULTS

Out of 1997 overdoses screened, 48 patients met inclusion/exclusion criteria. Patient characteristics were 43.8% male, median age 32 (range 18-87), mean initial salicylate concentration 28.1 mg/dL (SD 26.6), and 20.8% classified as severe outcome. Univariate analysis indicated that age, respiratory rate, lactate, coma, and the presence of co-ingestions were significantly associated with severe outcome, while initial salicylate concentration alone had no association. However, when adjusted for salicylate concentration, only age (OR 1.13; 95% CI 1.02-1.26) and respiratory rate (OR 1.29; 95% CI 1.02-1.63) were independent predictors. Additionally, lactate showed excellent test characteristics to predict severe outcome, with an optimal cutpoint of 2.25 mmol/L (78% sensitivity, 67% specificity).

CONCLUSIONS

In adult Emergency Department patients with acute salicylate poisoning, independent predictors of severe outcome were older age and increased respiratory rate, as well as initial serum lactate, while initial salicylate concentration alone was not predictive.

Multiple episodes of aspirin overdose in an individual patient: a case report

Introduction

Aspirin overdose, though now infrequently encountered, nevertheless continues to contribute to significant morbidity and mortality. The patient described in this case report intentionally ingested overdoses of aspirin on repeated occasions. The case provided an unusual and possibly one-of-a-kind opportunity to focus on the variability in the time course of plasma salicylate concentrations with current treatment modalities of aspirin overdose in an individual patient.

Case presentation

A 75-year-old Caucasian man who weighed 45kg and had an extensive history of various drug overdoses and stage 3 chronic kidney disease presented to a tertiary university hospital on three occasions within 2 months after successive overdoses of aspirin. During his third admission, he overdosed with aspirin, while on the ward recovering from the previous aspirin overdose. The overdoses were categorized as “potentially lethal” on two occasions and as “serious” in the other two, based on the alleged dose of aspirin ingested (over 500mg/kg in the first two overdoses, and 320mg/kg and 498mg/kg in the other two, respectively). However, as assessed by the observed salicylate concentrations, the ingestions would more appropriately have been categorized as being of “moderate” severity for the first and second overdose and “mild” severity for each of the others. This categorization was more consistent with the clinical severity of his admissions. A single dose of activated charcoal was administered only after the second overdose. On each occasion, he was given intravenous fluid with the aim of achieving euvolemia. Urinary alkalization was not attempted during the first admission, which was associated with the longest apparent elimination half-life of salicylate (30 hours). A plasma potassium concentration of approximately 4mmol/L appeared to be needed for adequate urinary alkalization.

Conclusion

In a patient with impaired renal function, intravenous fluid and urinary alkalization are the mainstays of treatment of aspirin overdose. Correction of hypokalemia is recommended. Repeated doses of charcoal may be a worthwhile intervention when there is no risk of aspiration. Our experience in this case also revealed considerable unexplained variation in management despite the availability of guidelines. It is, therefore, important to monitor the implementation of available guidelines.

Iatrogenic neurology

Iatrogenic disease is one of the most frequent causes of hospital admissions and constitutes a growing public health problem. The most common type of iatrogenic neurologic disease is pharmacologic, and the central and peripheral nervous systems are particularly vulnerable. Despite this, iatrogenic disease is generally overlooked as a differential diagnosis among neurologic patients. The clinical picture of pharmacologically mediated iatrogenic neurologic disease can range from mild to fatal. Common and uncommon forms of drug toxicity are comprehensively addressed in this chapter. While the majority of neurologic adverse effects are listed and referenced in the tables, the most relevant issues are further discussed in the text.

Salicylate toxicity from ingestion of traditional massage oil

A 16-month-old child developed a brief generalised tonic-clonic fitting episode and vomiting at home, after accidental ingestion of traditional massage oil. As the patient presented with clinical features of salicylate toxicity, appropriate management was instituted. He was admitted to the intensive care unit for multiorgan support. The child was discharged well 1&emsp14;week after the incident. Methyl-salicylate is a common component of massage oils which are used for topical treatment of joint and muscular pains. However, these massage oils may be toxic when taken orally. Early recognition of the salicylate toxicity is very important in producing a good patient outcome.

Evaluation and treatment of respiratory alkalosis

Respiratory alkalosis is the most frequent acid-base disturbance encountered in clinical practice. This is particularly true in critically ill patients, for whom the degree of hypocapnia directly correlates with adverse outcomes. Although this acid-base disturbance often is considered benign, evidence suggests that the alkalemia of primary hypocapnia can cause clinically significant decreases in tissue oxygen delivery. Mild respiratory alkalosis often serves as a marker of an underlying disease and may not require therapeutic intervention. In contrast, severe respiratory alkalosis should be approached with a sense of urgency and be aggressively corrected.

The glycine deportation system and its pharmacological consequences

The glycine deportation system is an essential component of glycine catabolism in man whereby 400 to 800mg glycine per day are deported into urine as hippuric acid. The molecular escort for this deportation is benzoic acid, which derives from the diet and from gut microbiota metabolism of dietary precursors. Three components of this system, involving hepatic and renal metabolism, and renal active tubular secretion help regulate systemic and central nervous system levels of glycine. When glycine levels are pathologically high, as in congenital nonketotic hyperglycinemia, the glycine deportation system can be upregulated with pharmacological doses of benzoic acid to assist in normalization of glycine homeostasis. In congenital urea cycle enzymopathies, similar activation of the glycine deportation system with benzoic acid is useful for the excretion of excess nitrogen in the form of glycine. Drugs which can substitute for benzoic acid as substrates for the glycine deportation system have adverse reactions that may involve perturbations of glycine homeostasis. The cancer chemotherapeutic agent ifosfamide has an unacceptably high incidence of encephalopathy. This would appear to arise as a result of the production of toxic aldehyde metabolites which deplete ATP production and sequester NADH in the mitochondrial matrix, thereby inhibiting the glycine deportation system and causing de novo glycine synthesis by the glycine cleavage system. We hypothesize that this would result in hyperglycinemia and encephalopathy. This understanding may lead to novel prophylactic strategies for ifosfamide encephalopathy. Thus, the glycine deportation system plays multiple key roles in physiological and neurotoxicological processes involving glycine.

Current management of salicylate-induced pulmonary edema

Salicylate-induced pulmonary edema (SIPE) can occur in both acute and chronic users of aspirin or salicylate products. The medical history, especially when it reveals the use of salicylates, is critical when considering this diagnosis. Unfortunately, the neurologic and systemic effects of salicylate toxicity may hinder the ability to obtain a reliable medical history. SIPE should be considered in patients who present with pulmonary edema and neurological changes, anion-gap metabolic acidosis, or possible sepsis. Some patients may be treated for "pseudosepsis" or other conditions, thereby delaying the diagnosis of salicylate intoxication. Misdiagnosis and possibly delayed diagnosis of SIPE can lead to a significant increase in morbidity and mortality. Serum and urine alkalinization by administration of intravenous sodium bicarbonate are commonly utilized therapeutic strategies. Finally, hemodialysis is a therapy which should be considered early in the course of treatment. The objective of this review was to emphasize the importance of rapid diagnosis and appropriate treatment in patients with SIPE, and summarize the current literature as it relates to the adult population.

Pharmacologically-induced metabolic acidosis: a review

Metabolic acidosis may occasionally develop in the course of treatment with drugs used in everyday clinical practice, as well as with the exposure to certain chemicals. Drug-induced metabolic acidosis, although usually mild, may well be life-threatening, as in cases of lactic acidosis complicating antiretroviral therapy or treatment with biguanides. Therefore, a detailed medical history, with special attention to the recent use of culprit medications, is essential in patients with acid-base derangements. Effective clinical management can be handled through awareness of the adverse effect of certain pharmaceutical compounds on the acid-base status. In this review, we evaluate relevant literature with regard to metabolic acidosis associated with specific drug treatment, and discuss the clinical setting and underlying pathophysiological mechanisms. These mechanisms involve renal inability to excrete the dietary H+ load (including types I and IV renal tubular acidoses), metabolic acidosis owing to increased H+ load (including lactic acidosis, ketoacidosis, ingestion of various substances, administration of hyperalimentation solutions and massive rhabdomyolysis) and metabolic acidosis due to HCO3- loss (including gastrointestinal loss and type II renal tubular acidosis). Determinations of arterial blood gases, the serum anion gap and, in some circumstances, the serum osmolar gap are helpful in delineating the pathogenesis of the acid-base disorder. In all cases of drug-related metabolic acidosis, discontinuation of the culprit medications and avoidance of readministration is advised.