Seizures after single-agent overdose with pharmaceutical drugs: analysis of cases reported to a poison center

Opioids, microglia, and temporal lobe epilepsy

A lack of treatment options for temporal lobe epilepsy (TLE) demands an urgent quest for new therapies to recover neuronal damage and reduce seizures, potentially interrupting the neurotoxic cascades that fuel hyper-excitability. Endogenous opioids, along with their respective receptors, particularly dynorphin and kappa-opioid-receptor, present as attractive candidates for controlling neuronal excitability and therapeutics in epilepsy. We perform a critical review of the literature to evaluate the role of opioids in modulating microglial function and morphology in epilepsy. We find that, in accordance with anticonvulsant effects, acute opioid receptor activation has unique abilities to modulate microglial activation through toll-like 4 receptors, regulating downstream secretion of cytokines. Abnormal activation of microglia is a dominant feature of neuroinflammation, and inflammatory cytokines are found to aggravate TLE, inspiring the challenge to alter microglial activation by opioids to suppress seizures. We further evaluate how opioids can modulate microglial activation in epilepsy to enhance neuroprotection and reduce seizures. With controlled application, opioids may interrupt inflammatory cycles in epilepsy, to protect neuronal function and reduce seizures. Research on opioid-microglia interactions has important implications for epilepsy and healthcare approaches. However, preclinical research on opioid modulation of microglia supports a new therapeutic pathway for TLE.

Uncovering the Hidden Burden of Pharmaceutical Poisoning in High-Income and Low-Middle-Income Countries: A Scoping Review

Pharmaceutical poisoning is a significant global public health concern, causing approximately 190,000 deaths annually. This scoping review aims to comprehensively map the available literature on pharmaceutical poisoning and compare patterns between high-income countries (HICs) and low-middle-income countries (LMICs). A systematic search was performed across the following databases: Embase, PubMed, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, and CINAHL. Studies included were from 1 January 2011 to 31 December 2020, in English, with full text available. Seventy-nine articles were included in the study; 21 were from LMICs and 58 were from HICs. Toxic exposure was largely intentional (77%) in LMICs and accidental (68%) in HICs. Drugs acting on the nervous system were responsible for 95% of toxicities worldwide with analgesics accounting for the largest subtherapeutic group in both LMICs (40%) and HICs (58%). Notable statistics were that HICs accounted for 99% of opioid overdoses, and LMICs accounted for 19% of anti-epileptic-induced toxicities. Overall, the medical outcomes due to poisonings were generally worse in LMICs. The review provides possible interventions to target specific geographic locations, based on the trends identified, to reduce the burden worldwide. Many gaps within the literature were recognised, calling for more robust analytical research.

Zinc oxide calcium silicate composite attenuates acute tramadol toxicity in mice

BACKGROUND

Seizures are considered to be the most common symptom encountered in emergency- rushed tramadol-poisoned patients; accounting for 8% of the drug-induced seizure cases. Although, diazepam clears these seizures, the risk of central respiratory depression cannot be overlooked. Henceforth, three adsorbing composites were examined in a tramadol acute intoxication mouse model.

METHODS

Calcium Silicate (Wollastonite) either non-doped or wet doped with iron oxide (3%Fe₂O₃) or zinc oxide (30% ZnO) were prepared. The composites' adsorption capacity for tramadol was determined in vitro. Tramadol intoxication was induced in Swiss albino mice by a parenteral dose of 120 mg/kg. Proposed treatments were administered within 1 min at 5 increasing doses, i.p. The next 30 min, seizures were monitored as an intoxication symptom. Plasma tramadol concentration was recorded after two hours of administration.

RESULTS

The 3% Fe₂O₃-containing composite (CSFe3), was found to be composed of mainly wollastonite with very little alpha-hematite. On the other hand, hardystonite and wellimite were developed in the 30%ZnO-containing composite (CSZn3). Micro-round and irregular nano-sized microstructures were established (The particle size of CS was 56 nm, CSFe3 was 49 nm, and CSZn3 was 42 nm). The CSZn3 adsorption capacity reached 1497 mg of tramadol for each gram. Tramadol concentration was reduced in plasma and seizures were inhibited after its administration to mice at three doses.

CONCLUSION

The calcium silicate composite doped with ZnO presented a good resolution of tramadol-induced seizures accompanied by detoxification of blood, indicating its potential for application in such cases. Further studies are required.

Efficacy and Safety of NSAIDs in Infants: A Comprehensive Review of the Literature of the Past 20 Years

Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used in infants, children, and adolescents worldwide; however, despite sufficient evidence of the beneficial effects of NSAIDs in children and adolescents, there is a lack of comprehensive data in infants. The present review summarizes the current knowledge on the safety and efficacy of various NSAIDs used in infants for which data are available, and includes ibuprofen, dexibuprofen, ketoprofen, flurbiprofen, naproxen, diclofenac, ketorolac, indomethacin, niflumic acid, meloxicam, celecoxib, parecoxib, rofecoxib, acetylsalicylic acid, and nimesulide. The efficacy of NSAIDs has been documented for a variety of conditions, such as fever and pain. NSAIDs are also the main pillars of anti-inflammatory treatment, such as in pediatric inflammatory rheumatic diseases. Limited data are available on the safety of most NSAIDs in infants. Adverse drug reactions may be renal, gastrointestinal, hematological, or immunologic. Since NSAIDs are among the most frequently used drugs in the pediatric population, safety and efficacy studies can be performed as part of normal clinical routine, even in young infants. Available data sources, such as (electronic) medical records, should be used for safety and efficacy analyses. On a larger scale, existing data sources, e.g. adverse drug reaction programs/networks, spontaneous national reporting systems, and electronic medical records should be assessed with child-specific methods in order to detect safety signals pertinent to certain pediatric age groups or disease entities. To improve the safety of NSAIDs in infants, treatment needs to be initiated with the lowest age-appropriate or weight-based dose. Duration of treatment and amount of drug used should be regularly evaluated and maximum dose limits and other recommendations by the manufacturer or expert committees should be followed. Treatment for non-chronic conditions such as fever and acute (postoperative) pain should be kept as short as possible. Patients with chronic conditions should be regularly monitored for possible adverse effects of NSAIDs.

The Timing of Clinical Effects of Bupropion Misuse Via Insufflation Reported to a Regional Poison Center

BACKGROUND

Bupropion is an antidepressant medication with expanding indications including smoking cessation, weight loss, attention-deficit/hyperactivity disorder, seasonal affective disorder, and amphetamine dependence. Despite its increasing popularity among providers, it has a well-known narrow therapeutic window that can lead to delayed onset of symptoms with extended-release formulations and devastating consequences in overdose. We have noticed some patients misusing bupropion via insufflation, which added a layer of complexity with regards to the therapeutic application of the drug. This route of use created difficult decisions regarding clinical monitoring in these patients.

OBJECTIVES

To determine if prolonged observation is required after insufflation of bupropion and to further describe effects from this route of use.

METHODS

This is a retrospective observational study reviewing all the cases of insufflated bupropion use reported to a single poison center without any other coingestants.

RESULTS

The majority (85.7%) of patients had mild or moderate effects, and seizures occurred in 19.6% of cases; and the vast majority of patients were symptomatic by the time of the initial call to the poison center. We did not encounter any delayed effects after this route of use.

CONCLUSIONS

This report describes the clinical effects reported, and the timing of these effects, after insufflation of bupropion.

Clinical effects of intravenous bupropion misuse reported to a regional poison center

Bupropion is an antidepressant medication with expanding indications including smoking cessation, weight loss, attention-deficit/hyperactivity disorder, seasonal affective disorder, and amphetamine dependence. Despite its increasing popularity among providers, it has a well-known narrow therapeutic window which can lead to delayed onset of symptoms with extended-release formulations and devastating consequences in overdose. We have noticed some patients misusing bupropion via intravenous use and had difficulty guiding decisions regarding clinical monitoring in these patients. As this route entirely changes the kinetics of bupropion, this has caused concern within our group. We reviewed all the cases of intravenous bupropion use reported to a single poison center without any other coingestants. The majority (66.7%) of patients had moderate effects and one patient had a seizure. No deaths were reported. All patients were symptomatic by the time of initial call to the poison center if they had any reported symptoms due to bupropion. This case series describes the clinical effects reported, and the timing of these effects, after intravenous bupropion use.

Common Opioids Involved in Drug Poisoning Presenting to the Emergency Department: A Cross-sectional Study

Objective:

Opioids poisoning is of the most important cause of mortality. The objective of the study was to compare the demographic factors, clinical manifestations, and outcomes of the most common opioids involved in drug overdose presenting to the Emergency Department.

Methods:

This cross-sectional study was conducted from October 2016 to March 2017 in the Clinical Toxicology Department of the main referral center of the university. All poisoning cases with common opioids were included in the study. Demographic factors, clinical manifestations, and outcome were recorded in a check list. ANOVA, Chi-square or Fisher's exact test, and binary logistic regression analysis were used for outcome prediction.

Findings:

Two hundred and thirty six patients with opioids poisoning were evaluated during the study period. The most common opioids involved in poisoning were methadone (47.9%), tramadol (24.2%), and opium (21.6%). Patients with opium poisoning were older than others (P < 0.0001). The rate of suicide was more in the tramadol group, while the past history of psychological problems was more observed in the methadone group (P < 0.0001). Increasing age (odds ratio [OR], 1.05; 95% confidence interval [CI]: 1.02–1.09; P = 0.05) and addiction (P = 0.01; OR, 7; 95% CI: 1.55–31.52) was associated with an increased complications or death. Also patients with somatic disease had more chance of complications/death (P = 0.04; OR, 3.71; 95% CI: 1.06–12.97). Kind of opioids was not a predictive factor in the outcome of the patients with acute poisoning.

Conclusion:

Age, addiction, and somatic disease should be considered as more important factors in outcome prediction with opioids poisoning, including opium, tramadol, and methadone.

Epilepsy: Workup and Management in Adults

When managing epilepsy, there is a temptation to focus care with respect to the last and the next seizure. However, epilepsy is a multifaceted chronic condition and should be treated as such. Epilepsy comes with many physical risks, psychological effects, and socioeconomic ramifications, demanding a long-term commitment from the treating physician. Patients with epilepsy, compared to other chronically ill patient populations, have a worse quality of life, family function, and less social support. The majority of patients are well controlled on antiseizure drugs. However, approximately one-third will continue to have seizures despite optimized medical management. The primary aim of this article is to explore the long-term management of chronic epilepsy, and to address some of the particular needs of patients with chronic epilepsy.

Meropenem at recommended dose is a potential risk for seizure in hemodialysis patient

Dosage adjustment of meropenem is usually recommended in hemodialysis (HD) patients and about 30% of meropenem is cleared during regular HD sessions. However, most of the published trials excluded patients on regular HD. Little is known about the accurate dosage of meropenem needed to avoid central nervous system toxicity. Herein, we report a 65-year-old Saudi female, a known case of end-stage renal disease on regular HD, who was admitted because of pyelonephritis and started on meropenem in the recommended dose according to cultures and sensitivity. She developed tonic-clonic convulsions after the 7^th dose. Seizures were completely aborted after discontinuation of the offending drug. The recommended dosage of 500 mg daily in HD patients may still be too high particularly in Asian patients owing to their relatively small body mass index.

Nature and sources of poisoning in patients admitted to a referral hospital in Gaborone, Botswana; findings and implications

BACKGROUND

Intentional poisoning is becoming an important public health concern particularly among young women globally. Consequently, there is a need to analyze this further within countries to establish pertinent policies to reduce current incidence rates. This includes sub-Saharan African countries where there has been a scarcity of information. Consequently, we sought to establish the nature and sources of poisoning in patients admitted to a leading hospital in Botswana to help develop pertinent future policies for Botswana and surrounding countries.

METHODS

Retrospectively reviewing the medical records of all patients admitted to Princess Marina Hospital (PMH), which is a leading tertiary hospital in the capital city of Botswana, due to acute poisoning over a six-year period.

RESULTS

The records for 408 patients were reviewed. The majority of admissions (58%) were females, and the mean age of patients was 21(±14) years. Most poisoning cases (53%) were intentional. The 15-45 years age group was most likely to intentionally poison themselves compared to other age groups, with females four and half times more likely to intentionally poison themselves compared to males (AOR 4.53, 95% CI: 2.68-7.89, p < 0.001). Half of the patients were poisoned by medicines followed by household chemicals (22%), with females overall four times more likely to be poisoned by medicines compared to males. The medicine mostly ingested was paracetamol (30%). Failing relationships (57%) were the principal reason for intentional poisoning. Six patients died from poisoning representing a 1.5% mortality rate.

CONCLUSIONS

The findings suggest in-depth and urgent investigations on intentional poisoning are needed among young women across countries including sub-Saharan African countries to inform future policies on prevention strategies. Further, strategies for poisoning prevention should target social and family relationship problems. We will be following this up in the future.

Substances Involved in Suicidal Poisonings in the United States

OBJECTIVE

This study investigated specific substances most commonly involved in suicidal poisonings, causing severe clinical effects, and leading to intensive treatments.

METHOD

Suicidal poisoning cases for individuals ≥13 years old were obtained from the National Poison Data System for 2011-2015. The most common products involved in single and multiple-product poisonings were identified. Single product cases were used to calculate substances causing the largest numbers of serious clinical effects and leading to intensive treatments.

RESULTS

More than half of reported cases involved only a single product (54.4%), but this frequency was higher at the extremes of age (66.7% in adolescents 13-19 years old and 70.5% in individuals ≥90 years old) and among pregnant women (65.8%). The top three substances involved in single-product poisonings were over-the-counter (OTC) medications, while alcohol and prescription sedatives were most common in multiple-product poisonings. One OTC medication, diphenhydramine, was a frequent cause of several serious clinical effects and intensive treatments.

CONCLUSIONS

Single product suicidal poisonings were more frequent with extremes of age and in pregnancy. OTC products were more frequently used in single product attempts. Products causing serious clinical effects can be targeted for suicide prevention efforts as well as education of health care providers.

Cytochrome P450-mediated inhibition of venlafaxine metabolism by trimipramine

OBJECTIVE

The aim of this study was to ensure patients' safety and to enhance treatment efficacy, knowledge about pharmacokinetic interactions even in complex clinical situations of polypharmacy is invaluable. This study is to uncover the potential of pharmacokinetic interactions between venlafaxine and trimipramine in a naturalistic sample.

METHODS

Out of a therapeutic drug monitoring database with plasma concentrations of venlafaxine (VEN) and O-desmethylvenlafaxine (ODV), we considered two groups of patients receiving venlafaxine without known cytochrome P450 confounding medications, taking solely venlafaxine: V0 (n = 905), and a group of patients co-medicated with trimipramine, VTRIM (n = 33). For VEN, ODV and active moiety (sum of VEN + ODV) plasma concentrations and dose-adjusted concentrations as well as ODV/VEN ratios were compared between groups using the Mann-Whitney U test with a significance level of 0.05.

RESULTS

Patients co-medicated with trimipramine had higher plasma concentrations of VEN (183.0 vs. 72.0, +154%, P = 0.002) and AM (324.0 vs. 267.5, +21%, P = 0.005) and higher dose adjusted plasma concentrations than patients in the control group (P = 0.001 and P = 0.003). No differences were found for ODV and C/D ODV (P < 0.05 for both comparisons). The metabolite to parent ratio, ODV/VEN, was significantly lower in the VTRIM group (1.15 vs. 2.37, P = 0.012).

CONCLUSION

Findings suggest inhibitory effects of trimipramine on venlafaxine pharmacokinetics most likely via an inhibition of CYP 2D6 or by saturated enzyme capacity. The lack of in vitro data hampers the understanding of the exact mechanisms. Clinicians should be aware of drug-drug interactions when combining these agents. Therapeutic drug monitoring helps to ensure treatment efficacy and patients' safety.

Seizures, Systemic Inflammatory Response, and Rhabdomyolysis Associated With Laboratory-Confirmed 2C-I and 25-I Exposure

The 2C drugs are hallucinogenic phenethylamines. They and their n-benzyloxymethyl analogs have become popular as "legal highs," and significant toxicity has been attributed to their use. We report on a case of seizures, systemic inflammatory response, and rhabdomyolysis associated with laboratory-confirmed 4-iodo-2,5-dimethoxyphenethylamine and 4-iodo-2,5-dimethoxy-N-(2-methoxybenzyl) phenethylamine exposure. A 17-year-old male teenager developed seizures after taking "2 strips of acid." The seizures resolved with midazolam, but he became apneic and was intubated. His head computed tomography was unremarkable. Initial creatinine level was 1.5 mg/dL, with a creatine kinase of 112 U/L. His urine immunoassay drug screen was negative. He was extubated within 12 hours but had elevated temperatures for 48 hours. He was treated with antibiotics, but no source of infection was identified. His creatinine level peaked at 2.46 mg/dL. His creatine kinase peaked 72 hours later at 14579 U/L. He was treated with intravenous fluids and did not require renal replacement therapy. He recovered fully and was discharged after 5 days. Serum and urine samples were tested using liquid chromatography time-of-flight mass spectrometry. We detected 4-iodo-2,5-dimethoxyphenethylamine and 4-iodo-2,5-dimethoxy-N-(2-methoxybenzyl) phenethylamine in both serum and urine. No other substances were detected. The 2C drugs and their n-benzyloxymethyl analogs are potent serotonergic agents. Their use has been associated with multiple adverse effects including seizures, rhabdomyolysis, and death. They should be considered in differential diagnosis for drug-induced seizures and as a cause for systemic inflammatory response. This case highlights the significant toxicity seen with these compounds.

Role of Endogenous Metabolite Alterations in Neuropsychiatric Disease

The potential role in neuropsychiatric disease risk arising from alterations and derangements of endogenous small-molecule metabolites remains understudied. Alterations of endogenous metabolite concentrations can arise in multiple ways. Marked derangements of single endogenous small-molecule metabolites are found in a large group of rare genetic human diseases termed "inborn errors of metabolism", many of which are associated with prominent neuropsychiatric symptomology. Whether such metabolites act neuroactively to directly lead to distinct neural dysfunction has been frequently hypothesized but rarely demonstrated unequivocally. Here we discuss this disease concept in the context of our recent findings demonstrating that neural dysfunction arising from accumulation of the schizophrenia-associated metabolite l-proline is due to its structural mimicry of the neurotransmitter GABA that leads to alterations in GABA-ergic short-term synaptic plasticity. For cases in which a similar direct action upon neurotransmitter binding sites is suspected, we lay out a systematic approach that can be extended to assessing the potential disruptive action of such candidate disease metabolites. To address the potentially important and broader role in neuropsychiatric disease, we also consider whether the more subtle yet more ubiquitous variations in endogenous metabolites arising from natural allelic variation may likewise contribute to disease risk but in a more complex and nuanced manner.

Prevalence and patterns of anti-epileptic medication prescribing in the treatment of epilepsy in older adults with intellectual disabilities

BACKGROUND

The prevalence of epilepsy is higher in people with intellectual disability (ID) and increases with the degree of ID. Although life expectancy for people with ID is increasing, people with ID coexisting with epilepsy have a higher mortality rate, particularly those who had recent seizures. There have been few observational studies of the prevalence and patterns of anti-epileptic prescribing among older people with ID and epilepsy. The aim of this study was to investigate prevalence and patterns of anti-epileptic prescribing in the treatment of epilepsy in a representative population of older people with ID and epilepsy.

METHODS

This was an observational cross-sectional study from wave 1 (2009/2010) of Intellectual Disability Supplement to the Irish Longitudinal Study on Aging, a nationally representative sample of 753 persons with ID aged between 41 and 90 years. Participants and/or proxies recorded medicines used on a regular basis and reported doctor's diagnosis of epilepsy; medication data were available for 736 (98%). Prescribing of anti-epileptic drugs (AEDs) for epilepsy in those with a doctor's diagnosis of epilepsy (N = 205) was the primary exposure of interest for this study. Participant exposure to these AEDs was then categorised into AED monotherapy and polytherapy. Participants/carers reported seizure frequency, when epilepsy was last reviewed and which practitioner reviewed epilepsy. In addition, medications that may lower the seizure threshold that were listed in the Maudsley prescribing guidelines in psychiatry were examined.

RESULTS

Of the 736 participants with reported medicines use, 38.9% (n = 287) were exposed to AEDs, and 30.6% (225) had a doctor's diagnosis of epilepsy. Of those with epilepsy (n = 225), 90.9% (n = 205) reported concurrent use of AEDs and epilepsy. Of these 205 participants, 50.3% (n = 103) were exposed to AED polytherapy, and 63 different polytherapy regimes were reported. The most frequently reported AEDs were valproic acid (n = 100, 48.7%), carbamazepine (n = 89, 46.3%) and lamotrigine (n = 57, 27.8%). In total, 13.7% had a concurrent psychotropic, which should be avoided in epilepsy, and 32.6% had a psychotropic where caution is required. Antipsychotics with potential epileptogenic potential accounted for 80% of these medications. Of those with AED polytherapy (n = 103), 29.5% (28) reported being seizure free for the previous 2 years.

CONCLUSIONS

Prevalence of epilepsy was high among older people with ID, and half were exposed to two or more AEDs. Despite the use of AED therapy, over half had seizures in the previous 2 years. As the primary goals of optimal AED treatment are to achieve seizure freedom without unacceptable adverse effects, this was not achievable for many older patients with ID and epilepsy. Our findings indicated that people with ID and epilepsy were often exposed to psychotropic medications that may lower the seizure threshold. Regular review of epilepsy and medicines (including medicines that may interact with AEDs or lower the seizure threshold) by multidisciplinary teams working to agreed standards may improve quality of prescribing. Improved exchange of information and coordination of care between specialists and primary care practitioners in line with expert consensus recommendations could bring substantial benefit.

Comparative pharmacology and toxicology of tramadol and tapentadol

Moderate-to-severe pain represents a heavy burden in patients' quality of life, and ultimately in the society and in healthcare costs. The aim of this review was to summarize data on tramadol and tapentadol adverse effects, toxicity, potential advantages and limitations according to the context of clinical use. We compared data on the pharmacological and toxicological profiles of tramadol and tapentadol, after an extensive literature search in the US National Library of Medicine (PubMed). Tramadol is a prodrug that acts through noradrenaline and serotonin reuptake inhibition, with a weak opioid component added by its metabolite O-desmethyltramadol. Tapentadol does not require metabolic activation and acts mainly through noradrenaline reuptake inhibition and has a strong opioid activity. Such features confer tapentadol potential advantages, namely lower serotonergic, dependence and abuse potential, more linear pharmacokinetics, greater gastrointestinal tolerability and applicability in the treatment of chronic and neuropathic pain. Although more studies are needed to provide clear guidance on the opioid of choice, tapentadol shows some advantages, as it does not require CYP450 system activation and has minimal serotonergic effects. In addition, it leads to less side effects and lower abuse liability. However, in vivo and in vitro studies have shown that tramadol and tapentadol cause similar toxicological damage. In this context, it is important to underline that the choice of opioid should be individually balanced and a tailored decision, based on previous experience and on the patient's profile, type of pain and context of treatment.

SIGNIFICANCE

This review underlines the need for a careful prescription of tramadol and tapentadol. Although both are widely prescribed synthetic opioid analgesics, their toxic effects and potential dependence are not completely understood yet. In particular, concerning tapentadol, further research is needed to better assess its toxic effects.

Central nervous system toxicity of mefenamic acid overdose compared with other NSAIDs: an analysis of cases reported to the United Kingdom National Poisons Information Service

AIMS

Case reports and small case series suggest increased central nervous system (CNS) toxicity, especially convulsions, after overdose of mefenamic acid, compared with other nonsteroidal anti-inflammatory drugs (NSAIDs), although comparative epidemiological studies have not been conducted. The current study compared rates of CNS toxicity after overdose between mefenamic acid, ibuprofen, diclofenac and naproxen, as reported in telephone enquiries to the UK National Poisons Information Service (NPIS).

METHODS

NPIS telephone enquiries related to the four NSAIDs, received between January 2007 and December 2013, were analysed, comparing the frequency of reported CNS toxicity (convulsions, altered conscious level, agitation or aggression, confusion or disorientation) using multivariable logistic regression.

RESULTS

Of 22 937 patient-specific telephone enquiries, 10 398 did not involve co-ingestion of other substances (mefenamic acid 461, ibuprofen 8090, diclofenac 1300, naproxen 547). Patients taking mefenamic acid were younger and more commonly female than those using other NSAIDs. Those ingesting mefenamic acid were more likely to experience CNS toxicity than those ingesting the other NSAIDs combined [adjusted odds ratio (OR) 7.77, 95% confidence interval (CI) 5.68, 10.62], especially convulsions (adjusted OR 81.5, 95% CI 27.8, 238.8). Predictors of CNS toxicity included reported dose and age, but not gender.

CONCLUSIONS

Mefenamic acid overdose is associated with a much larger and dose-related risk of CNS toxicity, especially convulsions, compared with overdose of other NSAIDs. The benefit-risk profile of mefenamic acid should now be re-evaluated in light of effective and less toxic alternatives.

Risk of Seizures Associated with Antidepressant Use in Patients with Depressive Disorder: Follow-up Study with a Nested Case-Control Analysis Using the Clinical Practice Research Datalink

INTRODUCTION

Antidepressant use has been associated with an increased risk of seizures. Evidence on the association between antidepressant use at therapeutic doses and seizures mainly comes from clinical trials that were not designed to investigate this potential relationship.

OBJECTIVE

The objective of this study was to assess the risk of first-time seizures in association with exposure to antidepressants in patients with depressive disorders.

METHODS

We conducted a retrospective follow-up study with a nested case-control analysis between 1998 and 2012, using data from the UK-based Clinical Practice Research Datalink (CPRD). We estimated crude incidence rates with 95 % confidence intervals (CIs) of seizures in depressed patients who used selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), 'other antidepressants', no antidepressants, or who had used antidepressants in the past. To adjust for potential confounding, we estimated odds ratios of antidepressant drug use among cases with seizures and matched controls in a nested case-control analysis.

RESULTS

Of 151,005 depressed patients, 619 had an incident seizure during follow-up. Incidence rates per 10,000 person-years were 12.44 (95 % CI 10.67-14.21) in SSRI users, 15.44 (95 % CI 8.99-21.89) in SNRI users, 8.33 (95 % CI 4.68-11.98) in TCA users, 9.33 (95 % CI 6.19-12.46) in non-users of antidepressants, and 5.05 (95 % CI 4.49-5.62) in past users of antidepressants. In the case-control analysis, relative risk estimates for seizures were increased in current users of SSRIs (adjusted odds ratio 1.98, 95 % CI 1.48-2.66) and SNRIs (adjusted odds ratio 1.99, 95 % CI 1.20-3.29), but not TCAs (adjusted odds ratio 0.99, 95 % CI 0.63-1.53), compared with non-users.

CONCLUSION

Current use of SSRIs or SNRIs was associated with a twofold increased risk of first-time seizures compared with non-use, while current use of TCAs (mostly low dose) was not associated with seizures. Treatment initiation in SSRI and SNRI users was associated with a higher risk of seizures than longer-term treatment.

Seizures associated with low-dose tramadol for chronic pain treatment

The management of cancer pain still poses a major challenge for clinicians. Tramadol is a centrally acting synthetic opioid analgesic. Its well-known side effects include nausea, vomiting, and dizziness; seizures are a rare side effect. Some reports have found that tramadol triggers seizure activity at high doses, whereas a few preclinical studies have found that this seizure activity is not dose-related. We herein present a case involving a patient with laryngeal cancer who developed seizures while on low-dose oral tramadol.

Antipsychotic-related fatal poisoning, England and Wales, 1993-2013: impact of the withdrawal of thioridazine

CONTEXT

Use of second generation antipsychotics in England and Wales has increased in recent years whilst prescription of first generation antipsychotics has decreased.

METHODS

To evaluate the impact of this change and of the withdrawal of thioridazine in 2000 on antipsychotic-related fatal poisoning, we reviewed all such deaths in England and Wales 1993-2013 recorded on the Office for National Statistics drug poisoning deaths database. We also reviewed antipsychotic prescribing in the community, England and Wales, 2001-2013. Use of routine mortality data: When an antipsychotic was recorded with other drug(s), the death certificate does not normally say if the antipsychotic caused the death rather than the other substance(s). A second consideration concerns intent. A record of "undetermined intent" is likely to have been intentional self-poisoning, the evidence being insufficient to be certain that the individual intended to kill. A record of drug abuse/dependence, on the other hand, is likely to have been associated with an unintentional death. Accuracy of the diagnosis of poisoning: When investigating a death in someone prescribed antipsychotics, toxicological analysis of biological samples collected post-mortem is usually performed. However, prolonged attempts at resuscitation, or diffusion from tissues into blood as autolysis proceeds, may serve to alter the composition of blood sampled after death from that circulating at death. With chlorpromazine and with olanzapine a further factor is that these compounds are notoriously unstable in post-mortem blood. Deaths from antipsychotics: There were 1544 antipsychotic-related poisoning deaths. Deaths in males (N = 948) were almost twice those in females. For most antipsychotics, the proportion of deaths in which a specific antipsychotic featured either alone, or only with alcohol was 30-40%, but for clozapine (193 deaths) such mentions totalled 66%. For clozapine, the proportion of deaths attributed to either intentional self-harm, or undetermined intent was 44%, but for all other drugs except haloperidol (20 deaths) the proportion was 56% or more. The annual number of antipsychotic-related deaths increased from some 55 per year (1.0 per million population) between 1993 and 1998 to 74 (1.5 per million population) in 2000, and then after falling slightly in 2002 increased steadily to reach 109 (1.9 per million population) in 2013. Intent: The annual number of intentional and unascertained intent poisoning deaths remained relatively constant throughout the study period (1993: 35 deaths, 2013: 38 deaths) hence the increase in antipsychotic-related deaths since 2002 was almost entirely in unintentional poisoning involving second generation antipsychotics. Clozapine, olanzapine, and quetiapine were the second generation antipsychotics mentioned most frequently in unintentional poisonings (99, 136, and 99 deaths, respectively). Mentions of diamorphine/morphine and methadone (67 and 99 deaths, respectively) together with an antipsychotic were mainly (84 and 90%, respectively) in either unintentional or drug abuse-related deaths. Deaths and community prescriptions: Deaths involving antipsychotics (10 or more deaths) were in the range 11.3-17.1 deaths per million community prescriptions in England and Wales, 2001-2013. Almost all (96%) such deaths now involve second generation antipsychotics. This is keeping with the increase in annual numbers of prescriptions of these drugs overall (<1 million in 2000, 7 million in 2013), largely driven by increases in prescriptions for olanzapine and quetiapine. In contrast, deaths involving thioridazine declined markedly (from 40 in 2000 to 10 in 2003-2013) in line with the fall in prescriptions for thioridazine from 2001.

CONCLUSIONS

The removal of thioridazine has had no apparent effect on the incidence of antipsychotic-related fatal poisoning in England and Wales. That such deaths have increased steadily since 2001 is in large part attributable to an increase in unintentional deaths related to (i) clozapine, and (ii) co-exposure to opioids, principally diamorphine and methadone.

Antidepressant or Antipsychotic Overdose in the Intensive Care Unit - Identification of Patients at Risk

It is often advised that patients who have ingested an overdose of antidepressants (AD) or antipsychotics (AP) are monitored with continuous ECG for minimum of 12-24 hr. These patients are often observed in an ICU. Our aim was to identify the number of patients with AD and/or AP overdose without adverse signs at hospital admission that turned out to need intensive care treatment. The effect of the antidepressants overdose risk assessment (ADORA) system was evaluated in patients with antidepressant as well as antipsychotic overdose. Our hypothesis was that patients with low ADORA do not need intensive care treatment. This retrospective study was conducted in adult patients admitted to the ICU at Odense University Hospital after an overdose with AP and/or AD between 1 January 2009 and 1 September 2014. Patients with predefined adverse signs in the emergency department were excluded due to obvious need of intensive care. Of the 157 patients included, 12 patients (8%) developed events during the ICU stay. Only 3 patients received intubation, vasoactive drugs and/or dialysis. None developed ventricular dysrhythmias. There were no fatalities. All the patients with low-risk assessment by ADORA within the first 6 hr did not develop events within the first 24 hr after hospital admission. The vast majority of patients with AD and/or AP overdose and no adverse signs at admission did not require intensive care treatment. Low-risk ADORA identified patients with antidepressant as well as antipsychotic overdose who would not require initial intensive care treatment. This is the first time the ADORA system has been evaluated in patients with antidepressant as well as antipsychotic overdose.

Treatment of drug-induced seizures

Seizures are a common complication of drug intoxication, and up to 9% of status epilepticus cases are caused by a drug or poison. While the specific drugs associated with drug-induced seizures may vary by geography and change over time, common reported causes include antidepressants, stimulants and antihistamines. Seizures occur generally as a result of inadequate inhibitory influences (e.g., gamma aminobutyric acid, GABA) or excessive excitatory stimulation (e.g. glutamate) although many other neurotransmitters play a role. Most drug-induced seizures are self-limited. However, status epilepticus occurs in up to 10% of cases. Prolonged or recurrent seizures can lead to serious complications and require vigorous supportive care and anticonvulsant drugs. Benzodiazepines are generally accepted as the first line anticonvulsant therapy for drug-induced seizures. If benzodiazepines fail to halt seizures promptly, second line drugs include barbiturates and propofol. If isoniazid poisoning is a possibility, pyridoxine is given. Continuous infusion of one or more anticonvulsants may be required in refractory status epilepticus. There is no role for phenytoin in the treatment of drug-induced seizures. The potential role of ketamine and levetiracetam is promising but not established.

Comparative Toxicity of Tapentadol and Tramadol Utilizing Data Reported to the National Poison Data System

Background: Tapentadol (TAP) and tramadol (TRA) provide pain relief through similar monoaminergic and opioid agonist properties. Objective: To compare clinical effects and medical outcomes between TAP and TRA exposures reported to the National Poison Data System of the American Association of Poison Control Centers. Methods: A retrospective cohort study was conducted analyzing national data for single medication TAP or TRA cases reported from June 2009 through December 2011. Case outcomes, dichotomized as severe versus mild; clinical effects; and use of naloxone were compared. Results: There were 217 TAP and 8566 TRA cases. Significantly more severe outcomes were associated with TAP exposures for an all-age comparison (relative risk [RR] = 1.24; 95% CI = 1.04-1.48), and for the <6-year-old age group (RR = 5.76; 95% CI = 2.20-15.11). Patients with TAP exposures had significantly greater risk of respiratory depression (RR = 5.56; 95% CI = 3.50-8.81), coma (RR = 4.16; 95% CI = 2.33-7.42), drowsiness/lethargy (RR = 1.38; 95% CI = 1.15-1.66), slurred speech (RR = 3.51; 95% CI = 1.98-6.23), hallucination/delusion (RR = 7.25; 95% CI = 3.61-14.57), confusion (RR = 2.54; 95% CI = 1.56-4.13) and use of naloxone (RR = 3.80; 95% CI = 2.96-4.88). TRA exposures had significantly greater risk of seizures (RR = 7.94; 95% CI = 2.99-20.91) and vomiting (RR = 1.96; 95% CI = 1.07-3.60). Conclusion: TAP was associated with significantly more toxic clinical effects and severe outcomes consistent with an opioid agonist. TRA was associated with significantly higher rates of seizures and vomiting.

Acute toxicity profile of tolperisone in overdose: Observational poison centre-based study

INTRODUCTION

Tolperisone is a centrally acting muscle relaxant that acts by blocking voltage-gated sodium and calcium channels. There is a lack of information on the clinical features of tolperisone poisoning in the literature. The aim of this study was to investigate the demographics, circumstances and clinical features of acute overdoses with tolperisone.

METHODS

An observational study of acute overdoses of tolperisone, either alone or in combination with one non-steroidal anti-inflammatory drug in a dose range not expected to cause central nervous system effects, in adults and children (< 16 years), reported to our poison centre between 1995 and 2013.

RESULTS

75 cases were included: 51 females (68%) and 24 males (32%); 45 adults (60%) and 30 children (40%). Six adults (13%) and 17 children (57%) remained asymptomatic, and mild symptoms were seen in 25 adults (56%) and 10 children (33%). There were nine adults (20%) with moderate symptoms, and five adults (11%) and three children (10%) with severe symptoms. Signs and symptoms predominantly involved the central nervous system: somnolence, coma, seizures and agitation. Furthermore, some severe cardiovascular and respiratory signs and symptoms were reported. The minimal dose for seizures and severe symptoms in adults was 1500 mg. In 11 cases the latency between the ingestion and the onset of symptoms was known and was reported to be 0.5-1.5 h.

CONCLUSIONS

The acute overdose of tolperisone may be life-threatening, with a rapid onset of severe neurological, respiratory and cardiovascular symptoms. With alternative muscle relaxants available, indications for tolperisone should be rigorously evaluated.