The serotonin syndrome and its treatment

Management of serotonin syndrome (toxicity)

Serotonin syndrome (toxicity), resulting from an excessive accumulation of serotonin in the central nervous system, it can occur due to various factors such as the initiation of medication, overdose or drug interactions. Diagnosing serotonin toxicity presents challenges as there are no definitive criteria. This review delves into the pathophysiology, incidence, clinical assessment and management of serotonin toxicity, stressing the significance of promptly recognizing and managing severe cases. Diagnosis relies primarily relies on clinical assessment due to the absence of specific laboratory tests. The Hunter Serotonin Toxicity criteria are commonly utilized but have only been validated in the overdose setting. Assessing the severity of toxicity is crucial for guiding management decisions. Supportive care, discontinuation of causative agents and symptomatic treatment are prioritized in management. Mild toxicity often requires withdrawal or reduction of the serotonergic agent, while more severe toxicity requires more aggressive resuscitative and supportive care. Severe serotonin toxicity characterized by hyperthermia and rigidity requires aggressive supportive measures, including benzodiazepines, intubation, paralysis and active cooling. Animal studies suggest potential benefits of 5-HT2A receptor antagonists in preventing hyperthermia and fatalities, but only at high doses. Their clinical effectiveness remains uncertain, and evidence is predominately from case series and case reports. Although commonly used, serotonin antagonists like cyproheptadine lack conclusive evidence of efficacy. Other serotonin antagonists such as chlorpromazine and olanzapine have been explored but evidence is limited to case reports. Hence, the cornerstone of treating severe cases does not lie in 'antidote' administration or even diagnosis but in effective early resuscitative and supportive care.

Serotonin syndrome controversies: A need for consensus

Serotonin syndrome (SS) is a drug-induced clinical syndrome resulting from increased serotonergic activity in the central nervous system. Although more than seven decades have passed since the first description of SS, it is still an enigma in terms of terminology, clinical features, etiology, pathophysiology, diagnostic criteria, and therapeutic measures. The majority of SS cases have previously been reported by toxicology or psychiatry centers, particularly in people with mental illness. However, serotonergic medications are used for a variety of conditions other than mental illness. Serotonergic properties have been discovered in several new drugs, including over-the-counter medications. These days, cases are reported in non-toxicology centers, such as perioperative settings, neurology clinics, cardiology settings, gynecology settings, and pediatric clinics. Overdoses or poisonings of serotonergic agents constituted the majority of the cases observed in toxicology or psychiatry centers. Overdose or poisoning of serotonergic drugs is uncommon in other clinical settings. Patients may develop SS at therapeutic dosages. Moreover, these patients may continue to use serotonergic medications even if they develop mild to moderate SS due to several reasons. Thus, the clinical presentation (onset, severity, and clinical features) in such instances may not exactly match what toxicologists or psychiatrists observe in their respective settings. They produce considerable diversity in many aspects of SS. However, other experts discount these new developments in SS. Since SS is a potentially lethal illness, consensus is required on several concerns related to SS.

Cerebral Anoxia in an 18-year-old Patient Being Treated for Major Depressive Disorder: How Forensic Detective Work Uses Medical Knowledge Including Clinical Pharmacology to Solve Cases

This column is the first of a 3-part series illustrating the importance of medical knowledge, including clinical pharmacology, in a forensic context. This first case involved an 18-year-old high school student who suffered an anoxic brain injury and remained in a state of permanent decorticate posture, unresponsive except for grunts and primitive movements until he died several years later. Our investigation began by ruling out plausible causes that were suggested by the defense in the malpractice suit. Once those possibilities were eliminated, the focus was on what accounted for the damage to the patient using general medical knowledge and clinical pharmacology. The 4 Ds of forensic psychiatry (duty, damages, dereliction, and direct cause) are the 4 elements that the plaintiff is required to prove in civil court to prevail in a malpractice suit and are applied to this case with a special focus on dereliction and direct cause. This catastrophic outcome was due to 3 factors. First, the patient had physiologically significant dehydration to the point that he had developed a reflex tachycardia to maintain his blood pressure. Second, the patient had been switched from extended to immediate-release quetiapine, resulting in a doubling of the peak concentration of the drug, which produced higher occupancy of alpha-1 adrenergic, histamine-1, and dopamine-2 receptors, causing a further drop in his blood pressure as well as increased sedation and impairment of his gag reflex. These effects occurred quickly because of the faster absorption of the IR formulation of the drug. Third, the patient had gone to sleep in a reclining chair so that his brain was above his heart and his lower extremities were below his heart, resulting in an increased "steal" of cardiac output going to his brain. These 3 factors together led the patient to aspirate and suffer a hypoxic brain injury after an episode of vomitus. This column explains the process by which the cause of this sad outcome was determined, how it was related to a dereliction of duty to the patient, and how other proposed causes were ruled out.

Cyproheptadine in serotonin syndrome: A retrospective study

Objective

Serotonin syndrome (SS) is an iatrogenic life-threatening condition caused by serotonergic agents. The treatment for SS involves the administration of a serotonin antagonist (cyproheptadine). However, the dosing schedule for cyproheptadine is not uniform in the literature.

Methods

We retrospectively evaluated 23 adult patients (>18 years) admitted to the Neurology Department and met the Hunter criteria for SS.

Results

The mean age was 35.2 years, and 52% were female. Ten patients were managed in the intensive care unit (ICU), whereas thirteen patients were admitted to the ward. Hyperreflexia was the most common clinical feature (100%), followed by clonus (91%), tachycardia (83%), and tremor (83%). Other common clinical features were rigidity (65%), increased bowel sound (61%), diaphoresis (48%), fever (43%), hypertension (39%), and myoclonus (30%). All but one patient received two or more serotonergic drugs. Tramadol was the most common serotonergic agent (39%), followed by sodium valproate (21%), and amitriptyline (21%). Cyproheptadine was administered to all patients. All patients admitted in the ICU received a loading dose of 12 mg followed by 2 mg every 2 h for at least 24 h. All patients admitted to the ward were given 4 mg of cyproheptadine three times each day. Every patient showed at least some response to cyproheptadine within 24 h. The total doses of cyproheptadine and the length of treatment differed between patients.

Conclusion

Any response to cyproheptadine at a therapeutic dose within 24 h, even a partial one, could be a diagnostic indicator of the existence of SS.

Medication-overuse headache overlapping with serotonin syndrome

Serotonin syndrome (SS) is an iatrogenic, drug-induced clinical syndrome caused by an increase in the intrasynaptic concentration of serotonin. Serotonin plays a significant role in the pathophysiology of migraines. Upregulation of 5-HT2A receptors is found in medication-overuse headache (MOH). Several migraine medications, both preventative and abortive drugs, act on serotonin receptors. We report two patients with chronic migraine who developed MOH. Besides headache, patients had frequent attacks of dizziness, restlessness, irritability, insomnia, excessive sweating, abdominal discomforts and tremors. These symptoms were suggestive of withdrawal headache. However, on physical examinations, we elicited hyperreflexia, hypertonia, clonus, tachycardia, hypertension, mydriasis and hyperactive bowel sound. Both patients also met the criteria for SS. Cyproheptadine was started. All features, including headaches, got better after cyproheptadine administration within 24 hours. In 7 days, there was practically total improvement. Both patients continued to take cyproheptadine as a preventative medicine, and migraine frequency was under control.

Drug-drug interactions involving classic psychedelics: A systematic review

Classic psychedelics, including lysergic acid diethylamide (LSD), psilocybin, mescaline, N,N-dimethyltryptamine (DMT) and 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT), are potent psychoactive substances that have been studied for their physiological and psychological effects. However, our understanding of the potential interactions and outcomes when using these substances in combination with other drugs is limited. This systematic review aims to provide a comprehensive overview of the current research on drug-drug interactions between classic psychedelics and other drugs in humans. We conducted a thorough literature search using multiple databases, including PubMed, PsycINFO, Web of Science and other sources to supplement our search for relevant studies. A total of 7102 records were screened, and studies involving human data describing potential interactions (as well as the lack thereof) between classic psychedelics and other drugs were included. In total, we identified 52 studies from 36 reports published before September 2, 2023, encompassing 32 studies on LSD, 10 on psilocybin, 4 on mescaline, 3 on DMT, 2 on 5-MeO-DMT and 1 on ayahuasca. These studies provide insights into the interactions between classic psychedelics and a range of drugs, including antidepressants, antipsychotics, anxiolytics, mood stabilisers, recreational drugs and others. The findings revealed various effects when psychedelics were combined with other drugs, including both attenuated and potentiated effects, as well as instances where no changes were observed. Except for a few case reports, no serious adverse drug events were described in the included studies. An in-depth discussion of the results is presented, along with an exploration of the potential molecular pathways that underlie the observed effects.

Serotonin syndrome: An often-neglected medical emergency

Optimum serotonin level in the serotonergic synapses of the central nervous system (CNS) is related to mood, behavior, and sleep. Serotonin syndrome (SS) is a rare yet very dangerous adverse effect resulting from increased serotonin in CNS. The diagnosis of SS is based on the presence of clinical symptoms, which can include agitation, confusion, rapid heart rate, high blood pressure, dilated pupils, muscle rigidity, tremors, sweating, and diarrhea. SS is invariably caused by inadvertent use of serotonergic medicines. There is an ever-growing list of medicines that are associated with the risk of SS. Some of the common classes of drugs that can contribute to the development of SS include selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, monoamine oxidase inhibitors, tricyclic antidepressants, stimulants (e.g., amphetamines and cocaine), lithium, opioids, drugs used for recreational purposes like ecstasy Methylenedioxymethamphetamine (MDMA), and some herbal supplements (e.g., St. John's Wort). SS can occur when these medications are taken alone or in combination, especially when a new medication is added, or the dose of an existing medication is changed. The management of SS typically involves discontinuing the use of the substance that caused the excess serotonin levels and providing supportive care, such as intravenous fluids and electrolytes. In severe cases, benzodiazepines may be used to control agitation and muscle rigidity, while serotonin antagonists, such as cyproheptadine, may be used to reduce serotonin levels. The literature review points to a general unawareness among physicians about the condition or drugs associated with it. Consequently, this potentially fatal condition is overlooked. There is a need for regular information updates and reminders to all those who prescribe medications to the patients.

A suspected case of serotonin syndrome induced by palonosetron and ramosetron administration

Serotonin syndrome occurs when serotonin (5-hydroxytryptamine, 5-HT) levels increase and is accompanied by symptoms of mental status changes, neuromuscular abnormalities, and autonomic hyperactivity. Serotonin receptor 3 antagonists, such as palonosetron or ramosetron, are commonly used for their antiemetic effects during general anesthesia. However, overdosage of these drugs carries a risk of serotonergic toxicity as they increase serum serotonin levels due to inhibition of serotonin reuptake. Serotonin syndrome caused by 5-HT3 antagonists is thought to be caused by the synergistic effects of high doses of serotonergic drugs or the combination of two or more serotonergic drugs with different mechanisms of action. The incidence of serotonin syndrome is unknown because it is a rare condition that cannot be selected for in randomized clinical trials. Therefore, physicians must focus on the clinical manifestations of the syndrome and manage patients before the condition becomes life-threatening.

Serotonin Syndrome From Duloxetine Monotherapy: A Case Report

Serotonin syndrome is a rare adverse reaction induced by serotonergic drugs. Most instances of the syndrome occur in the context of a serotonergic drug overdose and the combined use of monoamine oxidase inhibitors and other related drugs. We report a case of serotonin syndrome caused by duloxetine alone in an elderly Asian woman and review the literature. A 69-year-old woman was admitted to the hospital due to two months of irritability and reduced energy. She was diagnosed with depressive disorder in the outpatient department and took sertraline 75mg for one month, but there was no significant improvement of symptoms. After admission, sertraline was switched to duloxetine. After taking duloxetine 60mg, the patient developed confusion, inducible clonus, diaphoresis, tremor, hyperreflexia, and increased body temperature and blood pressure. Reviewing her history of drug exposure, physical examination, and associated laboratory tests, we ruled out other possible diseases and established a serotonin syndrome diagnosis. The symptoms and signs associated with serotonin syndrome disappeared within two days after treatments with hydration and diazepam and the withdrawal of duloxetine. Physicians should be watchful for serotonin syndrome, a rare, but in severe cases life-threatening, adverse drug reaction. It may occur with duloxetine monotherapy even at therapeutic doses.

Serotonin Syndrome: The Role of Pharmacology in Understanding Its Occurrence

Serotonin syndrome (SS) is a potentially fatal adverse drug reaction characterized by an exaggerated increase in serotonergic activity in the central and peripheral nervous systems. It presents a constellation of signs and symptoms related to behavioral changes, neuromuscular excitability, and autonomic instability. These symptoms can occur in both mild and severe forms. SS can be triggered by the therapeutic use of a drug that increases serotonin (5-HT) availability in the synaptic cleft or by the co-administration of two or more drugs that provide this increase. With the escalating use of antidepressants by the world's population, this adverse reaction may be more recurrent. However, SS is often overlooked by patients or not diagnosed by doctors. This review aims to improve awareness about SS and provide a pharmacological perspective to explain its occurrence. Evidence shows that other neurotransmitters may also be involved with the pathology of SS. Furthermore, SS and neuroleptic malignant syndrome (NMS) seem to be part of the same pathological spectrum, especially in atypical NMS cases. The emergence of the syndrome's symptoms may be closely related to pharmacokinetic and/or pharmacodynamic polymorphisms that lead to an increase in the 5-HT available to or 5-HT signaling by specific receptors, thus constituting an important area for future investigations.

[Central anticholinergic, neuroleptic malignant and serotonin syndromes]

Impaired consciousness is a frequent phenomenon after general anesthesia. In addition to the classical causes (e.g., overhang of sedatives), an impairment of consciousness can also be an adverse side effect of drugs. Many drugs used in anesthesia can trigger these symptoms. Alkaloids, such as atropine can trigger a central anticholinergic syndrome, opioids can promote the occurrence of serotonin syndrome and the administration of a neuroleptic can lead to neuroleptic malignant syndrome. These three syndromes are difficult to diagnose due to the individually very heterogeneous symptoms. Mutual symptoms, such as impaired consciousness, tachycardia, hypertension and fever further complicate the differentiation between the syndromes; however, more individual symptoms, such as sweating, muscle tension or bowl sounds can be helpful in distinguishing these syndromes. The time from the trigger event can also help to differentiate the syndromes. The central anticholinergic syndrome is the fastest to appear, usually taking just a few of hours from trigger to clinical signs, serotonin syndrome takes several hours up to 1 day to show and neuroleptic malignant syndrome usually takes days. The clinical symptoms can range from mild to life-threatening. Generally, mild cases are treated with discontinuation of the trigger and extended observation. More severe cases can require specific antidotes. The specific treatment recommended for central anticholinergic syndrome is physostigmine with an initial dose of 2 mg (0.04 mg/kg body weight, BW) administered over 5 min. For serotonin syndrome an initial dose of 12 mg cyproheptadine followed by 2 mg every 2 h is recommended (maximum 32 mg/day or 0.5 mg/kgBW day-1) but this medication is only available in Germany as an oral formulation. For neuroleptic malignant syndrome 25-120 mg dantrolene (1-2.5 mg/kgBW maximum 10 mg/kgBW day-1) is the recommended treatment.

[Central anticholinergic, neuroleptic malignant and serotonin syndromes : Important differential diagnoses in postoperative impairment of consciousness]

Impaired consciousness is a frequent phenomenon after general anesthesia. In addition to the classical causes (e.g., overhang of sedatives), an impairment of consciousness can also be an adverse side effect of drugs. Many drugs used in anesthesia can trigger these symptoms. Alkaloids, such as atropine can trigger a central anticholinergic syndrome, opioids can promote the occurrence of serotonin syndrome and the administration of a neuroleptic can lead to neuroleptic malignant syndrome. These three syndromes are difficult to diagnose due to the individually very heterogeneous symptoms. Mutual symptoms, such as impaired consciousness, tachycardia, hypertension and fever further complicate the differentiation between the syndromes; however, more individual symptoms, such as sweating, muscle tension or bowl sounds can be helpful in distinguishing these syndromes. The time from the trigger event can also help to differentiate the syndromes. The central anticholinergic syndrome is the fastest to appear, usually taking just a few of hours from trigger to clinical signs, serotonin syndrome takes several hours up to 1 day to show and neuroleptic malignant syndrome usually takes days. The clinical symptoms can range from mild to life-threatening. Generally, mild cases are treated with discontinuation of the trigger and extended observation. More severe cases can require specific antidotes. The specific treatment recommended for central anticholinergic syndrome is physostigmine with an initial dose of 2 mg (0.04 mg/kg body weight, BW) administered over 5 min. For serotonin syndrome an initial dose of 12 mg cyproheptadine followed by 2 mg every 2 h is recommended (maximum 32 mg/day or 0.5 mg/kgBW day^-1) but this medication is only available in Germany as an oral formulation. For neuroleptic malignant syndrome 25-120 mg dantrolene (1-2.5 mg/kgBW maximum 10 mg/kgBW day^-1) is the recommended treatment.

Predicting serotonin toxicity in serotonin reuptake inhibitor overdose

AIMS

We aimed to investigate the frequency of serotonin toxicity following overdose of antidepressants that inhibit serotonin reuptake and the factors that influence the probability of serotonin toxicity occurring.

METHODS

This was a retrospective cohort study of overdoses that included selective serotonin reuptake inhibitors (SSRIs) (70%) and serotonin norepinephrine reuptake inhibitors (SNRIs) (30%) admitted to a tertiary toxicology unit over 23 years. A multivariate mixed effects logistic regression model using NONMEM (7.2.0) was used to determine factors that influenced the probability of serotonin toxicity occurring.

RESULTS

There were 1978 overdoses in 1520 patients; median age 33 y (range: 13-86 years) and 64% female. Median defined daily dose equivalent (DDD) was 15 (1-420). Co-ingestants were taken in 1678/1978 (85%) overdoses: 11 co-ingested the monoamine oxidase-A inhibitor (MAOI) moclobemide, 99 (5%) co-ingested olanzapine, 58 (3%) co-ingested risperidone and 417 co-ingested a benzodiazepine (21%). Serotonin toxicity occurred in 269 overdoses (13.6%). The probability of serotonin toxicity increased slightly per 10 DDD units dose [OR, 1.01; 95% confidence intervals (CIs): 0.93-1.10], increased for an SNRI vs. an SSRI [OR, 1.07; 95% CI: 0.99-1.15], and markedly increased with co-ingestion of moclobemide [OR, 33.12; 95% CI: 7.5-147]. The probability decreased per 10 y age [OR, 0.84; 95% CI: 0.74-0.95], and with co-ingestion of the serotonin 2 A receptor (5-HT_2A) antagonists olanzapine [OR, 0.40; 95% CI: 0.17-0.94] or risperidone [OR, 0.13; 95% CI: 0.02-0.99]. The probability of serotonin toxicity was 12.5% at 1 DDD (therapeutic), 12.7% at 15 DDDs and 19% at 420 DDDs. In overdoses of the median dose of 15 DDDs, co-ingestion of moclobemide increased the probability to 83%, and co-ingestion of olanzapine or risperidone decreased it to 5.5% and 1.8%, respectively.

CONCLUSIONS

Serotonin toxicity is common following SSRI/SNRI overdose. Although dose increases probability, this was only a small effect. Co-ingestion with olanzapine or risperidone reduced the risk 2-6-fold, and moclobemide increased the risk 5-fold.

Recognition and Management of Serotonin Toxidrome in the Emergency Department-Case Based Review

Serotonin syndrome (SS) is a clinical toxidrome with high variability in clinical practice. It develops due to increased serotonin levels in the central nervous system. With an underestimated frequency, SS can develop following an overdose, a therapeutic dose increase, or drug to drug interaction of at least one serotonergic agent. It can present with autonomic signs, neuromuscular changes and an altered mental status. However, history and clinical examination are key features to formulate the diagnosis. Treatment options consist of supportive measures, discontinuation of the offending agent and certain therapeutic agents previously reported to improve outcomes. Physicians have limited experience with SS, partially due to the lack of its identification in clinical practice. Therefore, we have integrated, in a narrative review, the case of a young male with SS following an atypical antipsychotic overdose superimposed on chronic treatment with agents previously known to produce SS.

Dexmedetomidine in the treatment of toxicologic conditions: a systematic review and review of the toxicology investigators consortium database

INTRODUCTION

Dexmedetomidine is an alpha-2 adrenoceptor agonist which is widely used for sedation. Dexmedetomidine does not suppress the respiratory drive and produces a state of cooperative sedation; it may be associated with beneficial outcomes in the general critical care population. The role of dexmedetomidine in the treatment of toxicologic conditions (excluding alcohol withdrawal) is unclear.

OBJECTIVES

To critically assess and summarize the literature regarding the use of dexmedetomidine in toxicologic conditions other than alcohol withdrawal.

METHODS

We performed a systematic review of the medical literature to identify all existing evidence regarding the use of dexmedetomidine for toxicologic conditions. We excluded reviews and commentary, studies reporting exclusively on alcohol withdrawal, and studies reporting the use of dexmedetomidine to treat iatrogenic sedative withdrawal in the intensive care unit. We also performed a review of the Toxicology Investigators Consortium (ToxIC) database for patients treated with dexmedetomidine.

RESULTS

We identified 98 studies meeting inclusion criteria; 87 of these were case reports or case series, representing 99 unique cases. Eleven articles with other designs were identified, which included 138 patients treated with dexmedetomidine for toxicologic conditions. Ninety-three cases from the ToxIC registry met inclusion criteria. Common indications for dexmedetomidine included stimulant intoxication, sedative withdrawal, serotonin syndrome, antimuscarinic toxidrome, opioid withdrawal, and cannabinoid intoxication. Dexmedetomidine was usually administered by continuous infusion; bolus administration was reported in a minority of cases. Adverse effects were uncommon. The quality of evidence was generally low, given the preponderance of case reports, the rate of missing or poorly reported data, and the near-universal co-administration of other sedatives.

TREATMENT OF STIMULANT POISONING

Fifty-nine patients with stimulant poisoning were treated with dexmedetomidine. There was reasonably good evidence that dexmedetomidine was helpful in the treatment of stimulant poisoning.

TREATMENT OF SEDATIVE WITHDRAWAL

Twenty-two patients with sedative withdrawal were treated with dexmedetomidine. Several case reports of very high-quality suggested efficacy of dexmedetomidine for this indication, particularly for baclofen withdrawal.

TREATMENT OF SEROTONIN SYNDROME

Twenty-six patients with serotonin syndrome were treated with dexmedetomidine. This evidence was of lower quality due to missing clinical details, potential overdiagnosis of serotonin syndrome, and near-universal concomitant treatment with other sedatives.

TREATMENT OF ANTIMUSCARINIC POISONING

Forty-two patients with antimuscarinic poisoning were treated with dexmedetomidine. This evidence was of low quality and was limited by infrequent use of the preferred antidote, physostigmine.

TREATMENT OF OPIOID WITHDRAWAL

Forty-four patients with opioid withdrawal were treated with dexmedetomidine. This evidence was of low quality due to missing clinical details and near-universal concomitant treatment with other agents. The one high-quality trial reported the use of dexmedetomidine in ultra-rapid opioid detoxification, which is not indicated in modern practice.

TREATMENT OF CANNABINOID INTOXICATION

Five patients with cannabinoid intoxication were treated with dexmedetomidine. No definite conclusion can be drawn from the limited available evidence.

DISCUSSION

It is important to distinguish between the use of dexmedetomidine as a general sedative, which is likely to increase as the overall utilization of dexmedetomidine in critical care settings increases, and the use of dexmedetomidine as a specific pharmacologic treatment for a toxicologic condition. Well-established pharmacologic data from animal and human studies suggest dexmedetomidine counteracts stimulant-induced norepinephrine release. The mechanism by which dexmedetomidine treats sedative withdrawal is unclear. Some animal data show that dexmedetomidine may indirectly suppress serotonin release, which may suggest a role for dexmedetomidine in this condition.

CONCLUSIONS

There is a small and generally low-quality body of evidence which suggests that dexmedetomidine may be helpful in the treatment of certain toxicologic conditions, particularly stimulant intoxication and sedative withdrawal. Further high-quality research is needed to clarify the role of dexmedetomidine in patients with toxicologic conditions.

Clinically Relevant Drug Interactions with Monoamine Oxidase Inhibitors

Monoamine oxidase inhibitors (MAOI) are a class of drugs that were originally developed for the treatment of depression but have since been expanded to be used in management of affective and neurological disorders, as well as stroke and aging-related neurocognitive changes. Ranging from irreversible to reversible and selective to non-selective, these drugs target the monoamine oxidase (MAO) enzyme and prevent the oxidative deamination of various monoamines and catecholamines such as serotonin and dopamine, respectively. Tyramine is a potent releaser of norepinephrine (NE) and is found in high concentrations in foods such as aged cheeses and meats. Under normal conditions, NE is unable to accumulate to toxic levels due to the presence of MAO-A, an enzyme that degrades neurotransmitters, including NE. When MAO-A is inhibited, the capacity to handle tyramine intake from the diet is significantly reduced causing the brain to be vulnerable to overstimulation of postsynaptic adrenergic receptors with as little as 8-10 mg of tyramine ingested and can result in life-threatening blood pressure elevations. In addition to adverse reactions with certain foods, both older and newer MAOIs can negatively interact with both sympathomimetic and serotonergic drugs. In general, patients on a MAOI want to avoid two types of medications: those that can elevate blood pressure via sympathomimetic actions (e.g., phenylephrine and oxymetazoline) and those that can increase serotonin levels via 5-HT reuptake inhibition (e.g., dextromethorphan, chlorpheniramine, and brompheniramine). Illicit drugs that stimulate the central nervous system such as ecstasy (MDMA, 3,4-methylenedioxymethamphetamine) act as serotonin releasers. Patient involvement is also crucial to ensure any interaction within the healthcare setting includes making other providers aware of a MAOI prescription as well as avoiding certain OTC medications that can interact adversely with MAOIs.

High risk and low prevalence diseases: Serotonin syndrome

INTRODUCTION

Serotonin syndrome is a rare, frequently misdiagnosed, serious condition with high morbidity.

OBJECTIVE

This review highlights the pearls and pitfalls of serotonin syndrome, including diagnosis, initial resuscitation, and management in the emergency department (ED) based on current evidence.

DISCUSSION

Serotonin syndrome is a potentially deadly toxidrome marked by excess serotonin receptor activity or neurotransmission. Features of serotonin syndrome include 1) neuromuscular excitation such as tremor, hyperreflexia, and clonus; 2) autonomic dysfunction such as tachycardia, hypertension/hypotension, and hyperthermia; and 3) altered mental status such as agitation, delirium, and coma. Although serotonin syndrome may be more obvious in patients who have overdosed on serotonergic agents such as serotonin reuptake inhibitors (SSRIs), multiple other medications may also cause serotonin syndrome. Alternative diagnoses such as sepsis, neuroleptic malignant syndrome, and decompensated hyperthyroidism should be considered. The primary components of therapy include stopping the offending agent and supportive care, which focuses on agitation control, monitoring for and treating hyperthermia, and managing autonomic instability.

CONCLUSIONS

An understanding of serotonin syndrome can assist emergency clinicians in diagnosing and managing this disease.

R, Patel PH, Bazan DZ, Mora A, Samuel N, Mingle AC, Leon LR, Varon J, Surani S. Drug-Induced Hyperthermia Review

Humans maintain core body temperature via a complicated system of physiologic mechanisms that counteract heat/cold fluctuations from metabolism, exertion, and the environment. Overextension of these mechanisms or disruption of body temperature homeostasis leads to bodily dysfunction, culminating in a syndrome analogous to exertional heat stroke (EHS). The inability of this thermoregulatory process to maintain the body temperature is caused by either thermal stress or certain drugs. EHS is a syndrome characterized by hyperthermia and the activation of systemic inflammation. Several drug-induced hyperthermic syndromes may resemble EHS and share common mechanisms. The purpose of this article is to review the current literature and compare exertional heat stroke (EHS) to three of the most widely studied drug-induced hyperthermic syndromes: malignant hyperthermia (MH), neuroleptic malignant syndrome (NMS), and serotonin syndrome (SS). Drugs and drug classes that have been implicated in these conditions include amphetamines, diuretics, cocaine, antipsychotics, metoclopramide, selective serotonin reuptake inhibitors (SSRIs), tricyclic antidepressants (TCAs), and many more. Observations suggest that severe or fulminant cases of drug-induced hyperthermia may evolve into an inflammatory syndrome best described as heat stroke. Their underlying mechanisms, symptoms, and treatment approaches will be reviewed to assist in accurate diagnosis, which will impact the management of potentially life-threatening complications.

Drug Safety in Episodic Migraine Management in Adults Part 1: Acute Treatments

PURPOSE OF REVIEW

The aim of this review is to aid in choosing safe options when assessing potential risks of acute migraine treatments based on known mechanisms of action and anticipated safety concerns.

RECENT FINDINGS

Part 1 highlights safety issues associated with commonly used medications to treat acute migraine attacks. Strategies to mitigate cardiovascular and gastrointestinal risks of nonsteroidal anti-inflammatory drugs, evaluation of cardiovascular risks of triptan and ergot alkaloids, and precautions with use of antiemetics and the novel drugs gepants and ditans are discussed to help practitioners in clinical decision-making. When available, we included recommendations from professional societies and data from pharmacovigilance systems. While guidelines on efficacy are available, one must also consider the possible risks and adverse effects of a drug when creating treatment plans.

Hyperthermia and Serotonin: The Quest for a “Better Cyproheptadine”

Fine temperature control is essential in homeothermic animals. Both hyper- and hypothermia can have deleterious effects. Multiple, efficient and partly redundant mechanisms of adjusting the body temperature to the value set by the internal thermostat exist. The neural circuitry of temperature control and the neurotransmitters involved are reviewed. The GABAergic inhibitory output from the brain thermostat in the preoptic area POA to subaltern neural circuitry of temperature control (Nucleus Raphe Dorsalis and Nucleus Raphe Pallidus) is a function of the balance between the (opposite) effects mediated by the transient receptor potential receptor TRPM2 and EP3 prostaglandin receptors. Activation of TRPM2-expressing neurons in POA favors hypothermia, while inhibition has the opposite effect. Conversely, EP3 receptors induce elevation in body temperature. Activation of EP3-expressing neurons in POA results in hyperthermia, while inhibition has the opposite effect. Agonists at TRPM2 and/or antagonists at EP3 could be beneficial in hyperthermia control. Activity of the neural circuitry of temperature control is modulated by a variety of 5-HT receptors. Based on the theoretical model presented the “ideal” antidote against serotonin syndrome hyperthermia appears to be an antagonist at the 5-HT receptor subtypes 2, 4 and 6 and an agonist at the receptor subtypes 1, 3 and 7. Very broadly speaking, such a profile translates in a sympatholytic effect. While a compound with such an ideal profile is presently not available, better matches than the conventional antidote cyproheptadine (used off-label in severe serotonin syndrome cases) appear to be possible and need to be identified.

Preoperative Management of Medications for Psychiatric Diseases: Society for Perioperative Assessment and Quality Improvement Consensus Statement

There is a lack of guidelines for preoperative management of psychiatric medications leading to variation in care and the potential for perioperative complications and surgical procedure cancellations on the day of surgery. The Society for Perioperative Assessment and Quality Improvement identified preoperative psychiatric medication management as an area in which consensus could improve patient care. The aim of this consensus statement is to provide recommendations to clinicians regarding preoperative psychiatric medication management. Several categories of drugs were identified including antidepressants, mood stabilizers, anxiolytics, antipsychotics, and attention deficit hyperactivity disorder medications. Literature searches and review of primary and secondary data sources were performed for each medication/medication class. We used a modified Delphi process to develop consensus recommendations for preoperative management of individual medications in each of these drug categories. While most medications should be continued perioperatively to avoid risk of relapse of the psychiatric condition, adjustments may need to be made on a case-by-case basis for certain drugs.

The serotonin toxidrome: shortfalls of current diagnostic criteria for related syndromes

INTRODUCTION

Serotonin syndrome (toxicity) describes adverse drug effects from toxic amounts of intra-synaptic central nervous system serotonin. A wide range of drugs have been implicated to cause serotonin toxicity, not all justifiably. The plausible agents all have a final common pathway resulting in a substantial increase in central nervous system serotonergic neurotransmission. Serotonin toxicity is characterized by neuromuscular excitation, mental status changes, and autonomic dysregulation. Signs and symptoms represent a spectrum of toxicity (mild to life-threatening) related to increasing serotonin concentrations. As there is no consensus on the threshold for "toxicity" or diagnostic criteria, the true incidence of serotonin toxicity is unknown. The incidence in overdose is easier to quantify and is reasonably common in serotonergic antidepressant overdoses. In a large case series of overdoses, moderate serotonin toxicity occurred in 14% of poisonings with a selective serotonin reuptake inhibitor. While half those ingesting a monoamine oxidase inhibitor in combination with a serotonergic agent in overdose exhibit at least moderately severe serotonin toxicity. In contrast, the incidence of serotonin toxicity in those on therapeutic serotonergic agents appears to be very low.

OBJECTIVES

To provide a narrative review of the current diagnostic criteria, utilizing case reports of fatalities to evaluate how many meet the various diagnostic criteria and propose practical solutions to resolve controversies in diagnosis.

METHODS

A review of serotonin toxicity diagnostic criteria in the English literature was completed by searching Embase and PubMed from January 1990 to July 2021 for the keywords "serotonin syndrome/toxicity" paired with "diagnostic criteria" or "diagnosis." Also, fatal cases of serotonin toxicity identified from a recent systematic review were independently examined to determine what diagnostic criteria were met and whether serotonin toxicity or another cause was most likely.

REVIEW OF DIAGNOSIS CRITERIA

Serotonin toxicity is a clinical diagnosis, four diagnostic criteria (Sternbach, Serotonin Syndrome Scale, Radomski, and Hunter) have been proposed. However, the Serotonin Syndrome Scale has not been validated in patients with serotonin toxicity and only utilized in those on a serotonergic agent. The remaining three criteria are utilized more widely but have undergone little refinement or validation.

REVIEW OF FATAL CASES

Shortfalls with diagnostic criteria can be illustrated by examining case fatalities. Of 55 fatal cases reviewed, 12 (22%) were unlikely to be serotonin toxicity. Sternbach and Radomski criteria were met by 25 (45%), 20 (36%) had insufficient data reported and 10 (18%) met an exclusion criterion. Few had sufficient information reported to determine whether Hunter Criteria were met, with only 13 (24%) documented as meeting the criteria, the remaining 42 (76%) had insufficient data.

RESOLVING SHORTFALLS IN CURRENT DIAGNOSTIC CRITERIA

As serotonin toxicity is a clinical diagnosis, issues arise when basing the diagnosis on symptom criteria alone, without considering whether the drug/s ingested increase central nervous system serotonin or whether there is an alternative diagnosis. This has resulted in case reports and government warnings for drugs that cannot plausibly cause significant serotonin toxicity (e.g., ondansetron and antipsychotics). We propose when assessing for a serotonin toxidrome, both the causative agent(s) and clinical scenario is considered to determine the likelihood of serotonin toxicity. Then the clinical features assessed, those with a moderate to high prior probability (e.g., serotonergic drug-drug interaction, overdose, recent initiation or increase in dose of serotonergic agent/s) could be diagnosed based on the Hunter criteria. However, those with a low probability (e.g., stable therapeutic doses of a serotonergic agent) require more specific and stringent criteria. Finally, we propose a minimum dataset for case reports/series of serotonin toxicity.

CONCLUSIONS

More complete and accurate reporting of serotonin toxicity cases is required in the future, to avoid further misleading associations that are physiologically implausible.

A comparison of MDMA-assisted psychotherapy to non-assisted psychotherapy in treatment-resistant PTSD: A systematic review and meta-analysis

RATIONALE

Novel, evidence-based treatments are required for treatment-resistant post-traumatic stress disorder (PTSD). 3,4-Methylenedioxymethamphetamine (MDMA) has beneficially augmented psychotherapy in several small clinical trials.

OBJECTIVE

To review the use of MDMA-assisted psychotherapy in treatment-resistant PTSD.

METHODS

Systematic searches of four databases were conducted from inception to February 2020. A meta-analysis was performed on trials which were double-blinded, randomised, and compared MDMA-assisted psychotherapy to psychotherapy and placebo. The primary outcomes were the differences in Clinician Administered PTSD Scale (CAPS-IV) score and Beck's Depression Inventory (BDI). Secondary outcome measures included neurocognitive and physical adverse effects, at the time, and within 7 days of intervention.

RESULTS

Four randomised controlled trials (RCTs) met inclusion criteria. When compared to active placebo, intervention groups taking 75 mg (MD -46.90; 95% (confidence intervals) CI -58.78, -35.02), 125 mg (MD -20.98; 95% CI -34.35, -7.61) but not 100 mg (MD -12.90; 95% CI -36.09, 10.29) of MDMA with psychotherapy, had significant decreases in CAPS-IV scores, as did the inactive placebo arm (MD -33.20; 95% CI -40.53, -25.87). A significant decrease in BDI when compared to active placebo (MD -10.80; 95% CI -20.39, -1.21) was only observed at 75 mg. Compared to placebo, participants reported significantly more episodes of low mood, nausea and jaw-clenching during sessions and lack of appetite after 7 days.

CONCLUSION

These results demonstrate potential therapeutic benefit with minimal physical and neurocognitive risk for the use of MDMA-assisted psychotherapy in TR-PTSD, despite little effect on Beck's Depression Inventory. Better powered RCTs are required to investigate further.

INTERNATIONAL PROSPECTIVE REGISTER OF SYSTEMATIC REVIEWS

CRD42019109132 available online at www.crd.york.ac.uk/prospero.

Fatal serotonin syndrome: a systematic review of 56 cases in the literature

INTRODUCTION

Serotonin syndrome (SS) is a drug-induced potentially life-threatening clinical condition. There is a paucity of data on the risk factors, clinical course, and complications associated with fatal SS.

OBJECTIVE

To characterize the epidemiological profile, clinical features, and risk factors associated with fatal SS through a systematic review.

METHODS

We performed a systematic review of MEDLINE and Google Scholar for case reports, case series, or cohort studies of fatal SS.

RESULTS

Initial database search identified 2326 articles of which 46 (56 patients) were included in the final analysis. The mean age was 42.3 years (range 18-87 years) with female predominance (57%). North America and Europe constitute 80% of the reported fatal SS. The symptoms evolved very rapidly, within 24 h after the administration of serotonergic drugs in 59% of the cases. Fever (61%) was the most common symptom, followed by seizure (36%) and tremors (30%). The mean temperature in the reported cases (25 patients) was 41.6 ± 1.3 °C (range 38.3-43.5 °C). SS was reported to occur with the maintenance dosage of serotonergic agents, after initiation of the drug for the first time, and addition of the drugs for the development of another unrelated illness. Creatine kinase (CK) activities were elevated (>3 times of the upper limit of normal) in eighteen patients, and it was very high (>25,000 IU/L) in four patients. Presence of high grade fever, seizures, and high CK activities may be associated with severe SS. Nine patients (16%) received 5-HT2A antagonists as a therapy. About 50% of patients died within 24 h of the onset of symptoms.

CONCLUSIONS

While fatal SS is rare, frequently observed features include hyperthermia, seizures, and high CK activities. Cyproheptadine use appears infrequent for these patients.

Protracted hyperthermia and delayed rhabdomyolysis in ecstasy toxicity: A case report

RATIONALE

Despite toxicity and unpredictable adverse effects, ecstasy use has increased in the United States. Onset of hyperpyrexia, rhabdomyolysis, disseminated intravascular coagulation (DIC), among other symptoms, occurs within hours of ingestion. Moreover, patients who experience hyperpyrexia, altered mental status, DIC, and multiorgan failure, rarely survive. This case presents a chronic ecstasy user whose symptoms would have predicted mortality. The report demonstrates a patient who experiences protracted hyperthermia, with delayed rhabdomyolysis and DIC. In addition, his peak creatine kinase (CK) of 409,440 U/L was far greater than the expected 30,000 to 100,000 U/L, being the second largest CK recorded in a survivor.

PATIENT CONCERNS

This case report presents a 20-year-old man who presented to the emergency department after experiencing a severe reaction to ecstasy. He was a chronic user who took his baseline dosage while performing at a music event. He experienced hyperpyrexia immediately (106.5°F) while becoming stiff and unresponsive. Before emergency medical service arrival, his friends placed cold compresses on the patient and rested him in an ice filled bathtub.

DIAGNOSES

Per history from patient's friends and toxicology results, the patient was diagnosed with ecstasy overdose, which evolved to include protracted hyperthermia and delayed rhabdomyolysis.

INTERVENTIONS

Due to a Glasgow coma scale score of 5, he was intubated and sedated with a propofol maintenance. Hyperpyrexia resolved (temperature dropped to 99.1°F) after start of propofol maintenance. He was extubated after 24 hours, upon which he experienced hyperthermia (101.4°F at 48 hours), delayed rhabdomyolysis, and DIC (onset at 37 hours). He remained in hyperthermia for 120 hours until carvedilol permanently returned his temperature to baseline. His plasma CK reached a peak of 409,440 U/L at 35 hours.

OUTCOMES

After primary management with intravenous fluids, the patient returned to baseline health without any consequences and was discharged after 8 days. A follow-up of 3 months postdischarge revealed no complications or disability.

LESSONS

Clinically, the case highlights how physicians should be aware of the unusual time course adverse effects of ecstasy can have. Lastly, as intensity and duration of hyperpyrexia are predictors of mortality, our case indicates maintenance of sedation with propofol and use of oral carvedilol; both are efficacious for temperature reduction in ecstasy toxicity.

Serotonin Toxicity: Associated Agents and Clinical Characteristics

BACKGROUND

Serotonin toxicity is a common cause of drug-induced altered mental status. However, data on the causes of serotonin toxicity, symptomatology, complications, and rate of antidotal treatment are limited.

METHODS

This study evaluated cases of serotonin toxicity in the ToxIC registry, an international database of prospectively collected cases seen by medical toxicologists. Serotonin toxicity was diagnosed by bedside evaluation of medical toxicology specialists and explicit criteria were not used. The database was searched for "serotonin syndrome" between January 1, 2010, and December 31, 2016.

RESULTS

There were 1010 cases included. Females made up 608 (60%) cases. Ages are as follows: younger than 2 years (3, 0.3%), 2 to 6 years (8, 0.8%), 7 to 12 years (9, 0.9%), 13 to 18 years (276, 27.3%), 19 to 65 years (675, 67%), older than 66 years (33, 3.4%), unknown (6, 0.6%). Reasons for encounter: intentional (768, 76%), adverse drug event/reaction (127, 12.6%), unintentional (66, 6%), and unknown (55, 5.4%). Signs/symptoms: hyperreflexia/clonus/myoclonus (601, 59.5%), agitation (337, 33.4%), tachycardia (256, 25.3%), rigidity (140, 13.9%), seizures (139, 13.7%), and hyperthermia (29, 2.9%).

COMPLICATIONS

rhabdomyolysis (97, 9.7%), dysrhythmias (8, 0.8%), and death (1, 0.1%).

TREATMENTS

benzodiazepines 67% (677/1010), cyproheptadine 15.1% (153/1010). There were 192 different xenobiotics reported with 2046 total exposures. Antidepressants were most common (915, 44.7%) with bupropion the most frequent overall (147, 7.2%). Common non-antidepressants were dextromethorphan (95, 6.9%), lamotrigine (64, 3.1%), and tramadol (60, 2.9%).

DISCUSSION

Serotonin toxicity most often occurred in adult patients with intentional overdose. Antidepressants were the most common agents of toxicity. Interestingly, bupropion, a norepinephrine/dopamine reuptake inhibitor, was the most frequently mentioned xenobiotic. Though often cited as a potential antidote, only 15% of patients received cyproheptadine. Severe toxicity was rare. A single death was reported.

Life-Threatening Serotonin Syndrome Precipitated by Discontinuation of Serotonin-Dopamine Antagonist in the Presence of Serotonergic Agents: A Case Report

INTRODUCTION

Serotonin syndrome is caused by excessive activation of serotonin (5-hydroxytryptamine [5-HT]) neurotransmission. Although the discontinuation of antipsychotics with 5-HT2 receptor antagonistic characteristics could theoretically result in serotonin syndrome, there have been very few reports on the syndrome thus far.

CASE PRESENTATION

A 75-year-old woman with somatoform disorder was transferred to our emergency room because of pyrexia, unconsciousness, and myoclonus with hyperreflexia. She had been taking milnacipran and perospirone for 10 years and had started taking duloxetine 2 months before the event. Thereafter, she suffered diaphoresis, gait disturbance, and tremor. Her psychiatrist advised her to stop taking perospirone, because of suspicion of extrapyramidal symptoms, a day before admission. The clinical diagnosis of serotonin syndrome was made based on her symptoms while using serotonergic agents. Her symptoms were so severe that she was transferred to the intensive care unit, where supportive care was successful.

CONCLUSIONS

Discontinuation of antipsychotics that are 5-HT2 receptor antagonists may lead to serotonin syndrome in patients who take serotonergic agents. As extrapyramidal symptoms and serotonin toxicity share some clinical features, detailed drug history and physical examination are necessary for successful treatment.

Knowledge, Attitude, and Practice (KAP) Study on Serotonin Syndrome Among Neuro Physicians

Background and Aims:

Serotonin syndrome (SS) is a highly underdiagnosed drug-induced clinical syndrome. Under diagnosis is partly due to the unawareness of this syndrome by physicians. The aim of this study is to assess the knowledge, attitude and practice of SS among neuro physicians in India.

Methods:

A cross-sectional survey using a self-administered questionnaire was carried out among neuro physicians in India. Neuro physicians attending the various neurological conferences and meetings were approached to participate in the study.

Result:

A total of 150 neuro physicians responded to the survey. About 31% of participants correctly recognized the criteria for SS. Only 17% of the neuro physicians considered clonus as the most important feature in SS. Very few physicians correctly identified serotonergic agents causing serotonin syndrome. Similarly, a very low percentage of neuro physicians correctly identified the drugs used in the management of SS. Drugs used for the treatment of SS were incorrectly recognized as drugs causing SS. Clonus is the most specific feature for SS. However, examination for clonus is not a routine phenomenon in clinical practice among neuro physicians.

Conclusion:

This study shows great deficiencies in all domains of SS among neuro physicians. There is a need to make every doctor aware of SS by educational programs.

Metoclopramide-induced Serotonin Syndrome

Serotonin syndrome is a clinical diagnosis characterized by a constellation of autonomic and neurological physical examination findings due to the use of one or more serotonergic agents. Due to high morbidity and mortality associated with this condition, high index of suspicion is required in making this diagnosis. Treatment is aimed at discontinuation of the offending agent and supportive care. We present a case of a 28-year-old woman who presented with acetaminophen toxicity, however developed iatrogenic serotonin syndrome due to use of scheduled intravenous metoclopramide. Metoclopramide, by itself, very rarely causes serotonin syndrome and typically results in this condition when used in combination with other pro-serotonergic agents.

Serotonin Syndrome: Pathophysiology, Clinical Features, Management, and Potential Future Directions

Serotonin syndrome (SS) (also referred to as serotonin toxicity) is a potentially life-threatening drug-induced toxidrome associated with increased serotonergic activity in both the peripheral (PNS) and central nervous systems (CNS). It is characterised by a dose-relevant spectrum of clinical findings related to the level of free serotonin (5-hydroxytryptamine [5-HT]), or 5-HT receptor activation (predominantly the 5-HT_1A and 5-HT_2A subtypes), which include neuromuscular abnormalities, autonomic hyperactivity, and mental state changes. Severe SS is only usually precipitated by the simultaneous initiation of 2 or more serotonergic drugs, but the syndrome can also occur after the initiation of a single serotonergic drug in a susceptible individual, the addition of a second or third agent to long-standing doses of a maintenance serotonergic drug, or after an overdose. The combination of a monoamine oxidase inhibitor (MAOI), in particular MAO-A inhibitors that preferentially inhibit the metabolism of 5-HT, with serotonergic drugs is especially dangerous, and may lead to the most severe form of the syndrome, and occasionally death. This review describes our current understanding of the pathophysiology, clinical presentation and management of SS, and summarises some of the drugs and interactions that may precipitate the condition. We also discuss the newer novel psychoactive substances (NPSs), a growing public health concern due to their increased availability and use, and their potential risk to evoke the syndrome. Finally, we discuss whether the inhibition of tryptophan hydroxylase (TPH), in particular the neuronal isoform (TPH2), may provide an opportunity to pharmacologically target central 5-HT synthesis, and so develop new treatments for severe, life-threatening SS.

The Serotonin Syndrome: From Molecular Mechanisms to Clinical Practice

The serotonin syndrome is a medication-induced condition resulting from serotonergic hyperactivity, usually involving antidepressant medications. As the number of patients experiencing medically-treated major depressive disorder increases, so does the population at risk for experiencing serotonin syndrome. Excessive synaptic stimulation of 5-HT_2A receptors results in autonomic and neuromuscular aberrations with potentially life-threatening consequences. In this review, we will outline the molecular basis of the disease and describe how pharmacologic agents that are in common clinical use can interfere with normal serotonergic pathways to result in a potentially fatal outcome. Given that serotonin syndrome can imitate other clinical conditions, an understanding of the molecular context of this condition is essential for its detection and in order to prevent rapid clinical deterioration.

A genetic deletion of the serotonin transporter differentially influences the behavioural effects of MDMA

BACKGROUND

While (±)-3,4-methylenedioxymethamphetamine (MDMA) primarily induces serotonin release, it also affects dopamine and noradrenaline transmission. It is, however, unclear what role each of these neurotransmitters play in the behavioural profile of MDMA.

METHODS

In this study we used the drug discrimination (DD) and the acoustic startle (ASR) paradigms to examine the behaviour of rats with and without a genetic deletion of the serotonin transporter SERT (SERT^-/- and SERT^+/+ rats). In DD, rats were trained to respond on different levers following an injection of 1.5 mg/kg MDMA, or saline. After acquisition, they were given a challenge dose of 0.5 mg/kg amphetamine (AMPH). In the ASR paradigm, SERT^+/+ and SERT^-/- rats were given 0, 5 or 10 mg/kg MDMA.

RESULTS

In DD, significantly fewer SERT^-/- rats acquired MDMA discrimination. When the acquirers were challenged with AMPH, SERT^+/+ showed partial, while SERT^-/- rats showed full generalisation to MDMA. In the ASR paradigm, MDMA significantly reduced prepulse inhibition and startle habituation in SERT^+/+ rats, while having no effect in SERT^-/- rats.

CONCLUSION

Together these data suggest that in wildtype rats the interoceptive cues of MDMA are primarily mediated by serotonin and to a lesser extent by dopamine and noradrenaline, while the effects in the startle paradigm are almost exclusively mediated via serotonin. Together, these data contribute to our understanding of the complex pharmacodynamics of MDMA.

Serotonin Syndrome and the Anaesthetist

Serotonin syndrome results from excessive activation of serotonin (5-hydroxytryptamine; 5-HT) receptors in the nervous system, on the surface of platelets, and on the vascular endothelium. The clinical manifestations are a triad of altered conscious state, autonomic dysfunction, and neuromuscular excitability. Clinical diagnostic criteria remain poorly defined and unvalidated, and there are no available investigations to confirm the diagnosis. The syndrome is caused by the administration of one or more drugs possessing serotonergic activity. Severe forms of the syndrome usually result from overdose, but can be induced by monotherapy. The exact incidence of serotonin syndrome remains unknown, but is likely to be increasing due to increased prescription of selective serotonin reuptake inhibitor anti-depressants and tramadol, as well as recreational use of amphetamine-like substances. Serotonin syndrome may complicate the administration of drugs frequently used in anaesthetic practice, including pethidine and tramadol. Although the majority of cases improve with symptomatic and supportive care, severe cases need intensive care and frequently require mechanical ventilation. Neuromuscular excitability is likely to be the cause of rhabdomyolysis seen in severe cases and should be treated with benzodiazepines and muscle relaxants. Supportive therapies are required to treat hyperthermia and autonomic dysfunction. Cyproheptadine is the most commonly administered serotonergic antagonist, but is unavailable in parenteral form.

Dos distúrbios psiquiátricos à antibioticoterapia: reposicionamento da clorpromazina como agente antibacteriano

O alarmante aumento na taxa de resistência aos antibióticos põe em check à eficácia da terapia antibacteriana futura. Em contrapartida, as indústrias farmacêuticas negligenciam os investimentos em pesquisa e desenvolvimento de novos fármacos antimicrobianos em virtude de questões financeiras, legais e farmacológicas. Assim sendo, o reposicionamento de agentes disponíveis clinicamente torna-se uma promissora ferramenta para tentar driblar o desinteresse das indústrias. O fármaco antipsicótico clorpromazina (CPZ) destaca-se por possuir uma ampla faixa de atividade antibacteriana, a qual cobre desde patógenos Gram-positivos e Gram-negativos, até as micobactérias. A atividade antibacteriana é independente do perfil de susceptibilidade do microrganismo, sendo ela mantida mesmo em cepas altamente resistentes aos antibióticos. Alguns estudos mostram que mesmo nas concentrações clinicamente disponíveis no plasma (entre 0,1-0,5 μg/mL), a CPZ é capaz de matar Staphylococcus aureus e Mycobacterium tuberculosis dentro dos macrófagos. Em adição, estudos clínicos têm revelado os benefícios do uso da CPZ na terapia de suporte para pacientes com infecções em curso. Em conclusão, a CPZ pode eventualmente ser direcionada ao arsenal terapêutico antimicrobiano, especialmente no manejo das infecções causadas por microrganismos intracelulares com fenótipo multirresistente.

Drug-Induced Serotonin Syndrome

Serotonin syndrome is a potentially fatal condition caused by drugs that affect serotonin metabolism or act as serotonin receptor agonists. Monoamine oxidase inhibitors, selective serotonin reuptake inhibitors, and serotonin-norepinephrine reuptake inhibitors are the medications most commonly associated with serotonin syndrome. Serotonin syndrome can be mild and of short duration, but a prolonged course, life-threatening complications, and death are possible. Detection of serotonin syndrome is not difficult if the diagnostic criteria are understood and properly used, but the syndrome has no confirmatory tests and other drug-induced syndromes can, to a degree, mimic serotonin syndrome. The treatment is symptomatic and supportive. Antidotal therapies are available, but the evidence for their effectiveness is limited. If serotonin syndrome is promptly identified and aggressively treated, the patient should fully recover.

Octopamine signaling in the metazoan pathogen Schistosoma mansoni: localization, small-molecule screening and opportunities for drug development

Schistosomiasis is a tropical disease caused by a flatworm trematode parasite that infects over 200 million people worldwide. Treatment and control of the disease rely on just one drug, praziquantel. The possibility of drug resistance coupled with praziquantel's variable efficacy encourages the identification of new drugs and drug targets. Disruption of neuromuscular homeostasis in parasitic worms is a validated strategy for drug development. In schistosomes, however, much remains to be understood about the organization of the nervous system, its component neurotransmitters and potential for drug discovery. Using synapsin as a neuronal marker, we map the central and peripheral nervous systems in the Schistosoma mansoni adult and schistosomulum (post-infective larva). We discover the widespread presence of octopamine (OA), a tyrosine-derived and invertebrate-specific neurotransmitter involved in neuromuscular coordination. OA labeling facilitated the discovery of two pairs of ganglia in the brain of the adult schistosome, rather than the one pair thus far reported for this and other trematodes. In quantitative phenotypic assays, OA and the structurally related tyrosine-derived phenolamine and catecholamine neurotransmitters differentially modulated schistosomulum motility and length. Similarly, from a screen of 28 drug agonists and antagonists of tyrosine-derivative signaling, certain drugs that act on OA and dopamine receptors induced robust and sometimes complex concentration-dependent effects on schistosome motility and length; in some cases, these effects occurred at concentrations achievable in vivo The present data advance our knowledge of the organization of the nervous system in this globally important pathogen and identify a number of drugs that interfere with tyrosine-derivative signaling, one or more of which might provide the basis for a new chemotherapeutic approach to treat schistosomiasis.This article has an associated First Person interview with the first author of the paper.

Serotonin syndrome

Aims and method

To define serotonin syndrome and its symptoms and to discover which drugs or drug combinations are likely to cause it. A review of literature (including case reports) relating to serotonin syndrome collated from searches of MedLine and Micromedex covering the period January 1991 to July 1998.

Results

Most of the data found were either individual case reports or reviews of case reports. Reports of serotonin syndrome seem to be growing, certainly since the introduction of selective serotonin reuptake inhibitors. Particular combinations seem most likely to induce serotonin syndrome. Awareness of this syndrome as a distinct clinical entity seems to be growing.

Clinical implications

Serotonin syndrome is more likely to occur with drug combinations, especially those involving monoamine oxidase inhibitors. It can also occur when swapping antidepressant therapy, especially If changing from a long acting antidepressant such as fluoxetine. Caution is needed when changing antidepressants and particularly when they are used in combination.

Neuroleptic malignant syndrome and serotonin syndrome

The clinical manifestation of drug-induced abnormalities in thermoregulation occurs across a variety of drug mechanisms. The aim of this chapter is to review two of the most common drug-induced hyperthermic states, serotonin syndrome and neuroleptic malignant syndrome. Clinical features, pathophysiology, and treatment strategies will be discussed, in addition to differentiating between these two syndromes and differentiating them from other hyperthermic or febrile syndromes. Our goal is to both review the current literature and to provide a practical guide to identification and treatment of these potentially life-threatening illnesses. The diagnostic and treatment recommendations made by us, and by other authors, are likely to change with a better understanding of the pathophysiology of these syndromes.

Controversies in Serotonin Syndrome Diagnosis and Management: A Review

Over the past few years, Serotonin Syndrome (SS) has become a significant clinical concern. Over the last decade, United States saw a surge in antidepressant use. SS characteristically presents as the triad of altered mental status, autonomic dysfunction and neuromuscular excitation. Symptoms vary from patient to patient with mild cases presenting with subacute symptoms and severe cases progressing rapidly to death. Due to the protean manifestations of the syndrome along with non-specific prodromal, SS can easily be misdiagnosed if not carefully assessed. In severe cases, SS can be mistaken as neuroleptic malignant syndrome while mild cases are mostly misattributed to other causes such as flu. SS is a clinical diagnosis and therefore, requires a thorough review of medications and physical examination. Given the protean nature of this toxicologic syndrome various criteria were defined which includes Sternbach's, Radomski and Hunter's criteria. Keeping in mind the wide symptoms of serotonin syndrome from being barely perceptible to lethal emphasis there is a need to treat the syndrome on urgent basis. Mainstay for treatment of serotonin syndrome is to discontinue the offending drug. Improvement is seen in most patients within 24 hours.

Common toxidromes in movement disorder neurology

BACKGROUND

Physicians can come across patients who are exposed to certain prescription drugs or toxins that can result in adverse effects and complications which have high rates of morbidity and mortality.

OBJECTIVE

To summarise the key clinical features and management of the common movement disorder toxidromes relevant to physicians (with an interest in neurology).

METHODS

We searched PUBMED from 1946 to 2016 for papers relating to movement toxidromes and their treatment. The findings from those studies were then summarised and are presented here.

RESULTS

The key features of 6 of the common movement disorder toxidromes and their treatment are tabulated and highlighted. The management of toxidromes with the highest mortality like neuroleptic malignant syndrome and serotonin syndrome are discussed in detail.

CONCLUSION

There are several toxidromes that have the potential to become a serious life-threatening emergency if there is a delay in recognition of key clinical features and instituting the appropriate treatment at the earliest is crucial.