Ginsenoside Re Protects against Serotonergic Behaviors Evoked by 2,5-Dimethoxy-4-iodo-amphetamine in Mice via Inhibition of PKCδ-Mediated Mitochondrial Dysfunction.

It has been recognized that serotonin 2A receptor (5-HT2A) agonist 2,5-dimethoxy-4-iodo-amphetamine (DOI) impairs serotonergic homeostasis. However, the mechanism of DOI-induced serotonergic behaviors remains to be explored. Moreover, little is known about therapeutic interventions against serotonin syndrome, although evidence suggests that ginseng might possess modulating effects on the serotonin system. As ginsenoside Re (GRe) is well-known as a novel antioxidant in the nervous system, we investigated whether GRe modulates 5-HT2A receptor agonist DOI-induced serotonin impairments. We proposed that protein kinase Cδ (PKCδ) mediates serotonergic impairments. Treatment with GRe or 5-HT2A receptor antagonist MDL11939 significantly attenuated DOI-induced serotonergic behaviors (i.e., overall serotonergic syndrome behaviors, head twitch response, hyperthermia) by inhibiting mitochondrial translocation of PKCδ, reducing mitochondrial glutathione peroxidase activity, mitochondrial dysfunction, and mitochondrial oxidative stress in wild-type mice. These attenuations were in line with those observed upon PKCδ inhibition (i.e., pharmacologic inhibitor rottlerin or PKCδ knockout mice). Furthermore, GRe was not further implicated in attenuation mediated by PKCδ knockout in mice. Our results suggest that PKCδ is a therapeutic target for GRe against serotonergic behaviors induced by DOI.

Serotonin syndrome: a clinical review of current controversies.

Serotonin syndrome is a state of increased central and peripheral serotonin (5-hydroxytryptamine) activity. Unless recognized and treated early, serotonin syndrome can lead to seizures, shock and death. Both substances with direct and indirect serotonergic activity can precipitate the syndrome. Serotonin syndrome can occur not only in psychiatric but also in non-psychiatric settings. Yet, clinicians may not be familiar with the condition. We explore some of the current controversies regarding serotonin syndrome. Specifically, we tested the following assumptions: (i) Despite being rare, serotonin syndrome is still clinically relevant; (ii) The Hunter criteria are the gold standard for diagnosing serotonin syndrome; (iii) Hyperthermia is common in cases of serotonin syndrome; (iv) Serotonin syndrome usually develops fast; (v) Severe serotonin syndrome usually or almost exclusively involves monoamine oxidase inhibitors. We found that (i) despite being rare, serotonin syndrome was clinically relevant, (ii) the Hunter criteria could not be regarded as the gold standard for the diagnosis of serotonin syndrome since they missed more cases than the other two diagnostic criteria systems (Sternbach and Radomski criteria), (iii) Serotonin syndrome could occur in the absence of an elevated temperature, (iv) fast onset could not be regarded as a reliable clinical sign of serotonin syndrome, and (v) absence of monoamine oxidase inhibitors treatment did not exclude a diagnosis of serotonin syndrome. Clinicians should bear in mind that in the context of relevant drug history, serotonin syndrome may still be possible in these circumstances.

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.

[Hyponatremia associated with SSRI/NRSI: Descriptive and comparative epidemiological study of the incidence rates of the notified cases from the data of the French National Pharmacovigilance Database and the French National Health Insurance]. / Les hyponatrémies sous ISRS/IRSNA : étude épidémiologique descriptive et comparative des taux d'incidence de cas notifiés à partir des données de la Banque nationale de pharmacovigilance et de l'Assurance maladie.

INTRODUCTION: Selective Serotonin Reuptake Inhibitors (SSRIs) and Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs) are frequently prescribed. These antidepressants can potentially induce serious hyponatremia through the SIADH syndrome. That seems to concern all molecules of these classes but the individual risk of each molecule is not well known. The aims of the study were to compare the incidence rate of each molecule in order to identify the existence of molecules more at risk of inducing hyponatremia and to characterize a profile of patients at risk for hyponatremia during a treatment with a SSRI or a SNRI. METHOD: The cases of hyponatremia under SSRI/SNRI were extracted from the French pharmacovigilance database (BPNV). The exposition to the different SSRIs/SNRIs in the French population was estimated from the French National Health Insurance database (SNIIRAM) using a sampled database (Echantillon Généralistes des Bénéficiaires). The study ran from 01/01/2011 to 31/12/2013. The primary study endpoint was the incidence rate of notifications of the hyponatremia cases in patients treated by SSRI/SNRI and recorded into the BNPV database, related to the average annual number of corresponding treatments initiated during the same period. RESULTS: The number of cases of hyponatremia included in the study was 169 for 3 749 800 adult patients initiating treatment. The incidence rate of cases was 1.64 for 100 000 persons per year (PY). The standardized incidence rates between the different molecules showed no difference except for duloxetine (2.79/100 000 PY p > 0.03). Identified risk factors were age, with a large increase of incidence rate from 75 years old (incidence 12.5 higher) and female gender. CONCLUSIONS: Comparison of the incidence rates from spontaneous reports indicates a greater risk of hyponatremia for duloxetine for 2011-2013. This result needs to be confirmed by other studies. The advanced age and female sex are risk factors, irrespective of the molecule.

Malignant Syndrome and Serotonin Syndrome in a General Hospital Setting: Clinical Features, Frequency and Prognosis.

Objective The differences in the frequency and clinical features of malignant syndrome (MS) and serotonin syndrome (SS) in same population have only rarely been reported. To report the frequency and clinical features of MS and SS in a general hospital setting. Methods The clinical and laboratory features of patients with MS and those with SS, who were consecutively admitted to Chiba Rosai Hospital, during the past 4.5 years were reviewed. Results Of the 2005 patients admitted, MS was observed in 16 patients (0.8%) and SS in 2 (0.1%). In the 16 patients with MS, the underlying disorder included depression (n = 5), and dementia or parkinsonism (n = 11). The underlying etiology of the 2 patients with SS was depression. In 5 patients, MS was difficult to distinguish from SS because of overlapping symptoms and signs and/or treatments with both neuroleptic and serotoninergic drugs. Of the 16 patients with MS, 1 died, 1 remained wheelchair-bound, 4 were able to walk with assistance, and 10 regained their ability to ambulate independently. The 2 patients with SS recovered after cyproheptadine therapy and were discharged on foot. Conclusion MS occurs more frequently than SS in the general hospital setting. Underlying aetiologies in patients with MS were more common due to dementia or parkinsonism than in patients with psychiatric disorders. The differential diagnosis of MS and SS is often difficult and the diagnostic sensitivities largely differ for each of the diagnostic criteria. As a result, the establishment of new diagnostic criteria that specifically focus on distinguishing MS from SS is therefore required.

Acute Presentation of Nonmotor Symptoms in Parkinson's Disease.

There are a few syndromes involving the nonmotor symptoms of Parkinson's disease and other movement disorders that can quickly lead to severe morbidity and mortality, and, as such, need rapid identification and management. Among these are neuroleptic malignant syndrome, serotonin syndrome, dopamine agonist withdrawal syndrome, and dystonic storm. It is important to maintain a high index of suspicion for these disorders as lack of identification can lead to death. Many of these acutely occurring nonmotor syndromes are primarily the result of imbalances in dopaminergic and serotonergic systems due to changes in pharmacologic management of psychiatric disorders or Parkinson's disease. We discuss these acutely occurring nonmotor symptoms in order to raise awareness and also to highlight how these extremes in symptoms may uniquely shed light on the pathophysiology of Parkinson's disease.

Serotonergic medications, herbal supplements, and perioperative serotonin syndrome.

PURPOSE: Perioperative use of serotonergic agents increases the risk of serotonin syndrome. We describe the occurrence of serotonin syndrome after fentanyl use in two patients taking multiple serotonergic agents. CLINICAL FEATURES: Two patients who had been taking multiple serotonergic medications or herbal supplements (one patient taking fluoxetine, turmeric supplement, and acyclovir; the other taking fluoxetine and trazodone) developed serotonin syndrome perioperatively when undergoing outpatient procedures. Both experienced acute loss of consciousness and generalized myoclonus after receiving fentanyl. In one patient, the serotonin syndrome promptly resolved after naloxone administration. In the other patient, the onset of serotonin syndrome was delayed and manifested after discharge, most likely attributed to the intraoperative use of midazolam for sedation. CONCLUSION: Even small doses of fentanyl administered to patients taking multiple serotonergic medications and herbal supplements may trigger serotonin syndrome. Prompt reversal of serotonin toxicity in one patient by naloxone illustrates the likely opioid-mediated pathogenesis of serotonin syndrome in this case. It also highlights that taking serotonergic agents concomitantly can produce the compounding effect that causes serotonin syndrome. The delayed presentation of serotonin syndrome in the patient who received a large dose of midazolam suggests that outpatients taking multiple serotonergic drugs who receive benzodiazepines may require longer postprocedural monitoring.

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.

Serotonin Syndrome from 5-Hydroxytryptophan Supplement Ingestion in a 9-Month-Old Labrador Retriever.

INTRODUCTION: 5-Hydroxytryptophan (5-HTP) supplements are available over the counter and labeled as sleeping aids and anxiolytics for human use. 5-HTP is a serotonin precursor and overdose can lead to serotonin syndrome. CASE REPORT: A 9-month-old female Labrador retriever was evaluated after ingestion of a 5-HTP supplement. Signs of agitation developed within 1 h of ingestion, and emesis was attempted by the owner with  3% hydrogen peroxide (H2O2) orally. On presentation, the dog was obtunded, bilaterally mydriatic and salivating. Physical exam revealed tachypnea, tachycardia, hyperthermia, and hypertension. Eighteen hours post presentation, the dog developed melena, hematemesis, and pigmenturia. A hemogram revealed mild anemia with evidence of oxidative erythrocyte damage (eccentrocytes, Heinz bodies, and siderocytes). A chemistry panel revealed markedly elevated creatine kinase and hyperbilirubinemia, supporting hemolytic anemia. A urinalysis revealed pigmenturia. Hemolytic anemia was presumed to be caused by oxidative damage secondary to gastrointestinal ulceration and circulatory embolism of H2O2. Treatment included fluid therapy, a mannitol constant rate infusion, antiemetics, gastroprotectants, and cyproheptadine as a serotonin antagonist. The patient responded well to treatment and was discharged within 48 h of presentation. DISCUSSION: Serotonin syndrome is an increasingly common toxic syndrome in veterinary medicine with the availability of over-the-counter medications that alter serotonin metabolism. The importance of appropriate client education regarding emesis with H2O2 is highlighted.

[Malignant hyperthermia syndrome in the intensive care unit : Differential diagnosis and acute measures]. / Maligne hypertherme Syndrome auf der Intensivstation : Differenzialdiagnostik und Akutmaßnamen.

Malignant hyperthermia is a life-threatening disease caused by derangement of the autonomic nerve system and hypermetabolism of the peripheral musculature. Commonly body core temperatures of more than 40 °C will be found in this disease which is caused mostly by psychopharmacological drugs like antidepressants, neuroleptics but also antibiotics, pain killers, anti-Parkinson drugs, and volatile anesthetics. The inducers of malignant hyperthermia interact with postsynaptic receptors (serotonin, anticholinergics) or muscular intracellular structures responsible for calcium utilization (volatile anesthetics, succinylcholine). Rarely malignant hyperthermia is a consequence of mental stress or vigorous exercise and or heat. Malignant hyperthermic syndromes lead to a severe dysbalance of the autonomic nerve system accompanied by rhabdomyolysis, disseminated intravascular coagulopathy, and finally multi-organ failure. Accordingly, medical management is primarily directed to stabilize vital functions, withdrawal of the causing drug, and if possible antagonizing toxic substances. The leading symptom hyperthermia needs to be treated physically with available cooling systems.

Effects of fentanyl on serotonin syndrome-like behaviors in rats.

Emerging evidence from case reports suggests that fentanyl may precipitate potentially life-threatening serotonin syndrome in patients taking serotonergic drugs. However, the underlying mechanism of the association between serotonin syndrome and fentanyl remains under investigation. We therefore investigated the pharmacological effects of an analgesic dose of fentanyl (0.2 mg/kg) injected subcutaneously (s.c.) on serotonergic toxicity-like responses in rats. Rats were s.c. injected with 0.75 mg/kg 8-OH-DPAT, a full 5-HT1A agonist, as an animal model of serotonin syndrome. The 8-OH-DPAT-treated rats showed well-characterized serotonin syndrome-like behaviors (low body posture, forepaw treading), hyperlocomotion, and decreased body temperature. Rats injected s.c. with fentanyl alone showed no significant changes in any of the parameters measured, while concomitant administration of fentanyl + 8-OH-DPAT resulted in exaggerated 8-OH-DPAT-induced serototoxic responses. A separate dose-response experiment showed that the serototoxic effect of fentanyl was dose-dependent. Pretreatment with naloxone [2.0 mg/kg, intraperitoneal (i.p.) injection], an opioid receptor antagonist, failed to antagonize the fentanyl-induced exaggerated serotonin syndrome-like behaviors. In contrast, pretreatment with WAY-100653, a serotonin 5-HT1A receptor antagonist (0.5 mg/kg, i.p. injection) completely inhibited all responses. Our findings provide preclinical proof-of-concept that an analgesic dose of fentanyl enhances serotonin toxicity, likely via its serotonin-reuptake inhibitory activity, independently of interaction with the opioid receptors.

Serotonin syndrome overlapping with neuroleptic malignant syndrome: A case report and approaches for differentially diagnosing the two syndromes.

Serotonin syndrome (SS) and neuroleptic malignant syndrome (NMS) are life-threatening adverse reactions caused by serotonergic antidepressants and neuroleptics, respectively. SS and NMS have overlapping clinical features, and thus differentially diagnosing the syndromes can be difficult in patients who are taking both types of drugs. Here, the author reports a unique case of a patient who developed SS that overlapped with NMS after taking imipramine and lithium carbonate with the subsequent addition of metoclopramide. This is the first case report of SS that overlapped with NMS. The author also briefly summarizes the clinical symptoms of each syndrome and describes the approaches that were used to differentially diagnose the two syndromes.

Tramadol overdose causes seizures and respiratory depression but serotonin toxicity appears unlikely.

CONTEXT: Tramadol is a commonly used centrally acting analgesic associated with seizures and suspected to cause serotonin toxicity in overdose. OBJECTIVE: This study sought to investigate the effects of tramadol overdose, and included evaluation for serotonin toxicity based on the Hunter Serotonin Toxicity Criteria where the seven clinical features of spontaneous clonus, inducible clonus, ocular clonus, agitation, diaphoresis, tremor and hyperreflexia are examined for in all patients taking serotonergic medications; seizures and central nervous system depression. MATERIALS AND METHODS: This was an observational cases series based on a retrospective review of tramadol overdoses (> 400 mg) admitted to a tertiary toxicology unit from November 2000 to June 2013. Demographic details, information on ingestion (dose and co-ingestants), clinical effects, complications (seizures, serotonin toxicity and cardiovascular effects) and intensive care unit (ICU) admission were extracted from a clinical database. RESULTS: There were 71 cases of tramadol overdose (median age: 41 years, range: 17-69 years; and median ingested dose: 1000 mg, interquartile range [IQR]: 800-2000 mg). Seizures were dose related and occurred in 8 patients, one of them co-ingested a benzodiazepine compared with 16 patients without seizures. There were no cases of serotonin toxicity meeting the Hunter Serotonin Toxicity Criteria. Tachycardia occurred in 27 and mild hypertension occurred in 32. The Glasgow Coma Score was < 15 in 29 and < 9 in 5 patients; three co-ingested tricyclic antidepressants and two tramadol alone (3000 mg and 900 mg). Respiratory depression occurred in 13, median dose: 2500 (IQR: 1600-3000) mg which was significantly different (p = 0.003) to patients without respiratory depression, median dose: 1000 (IQR: 750-1475) mg. Eight patients were admitted to ICU, five due to co-ingestant toxicity and three for respiratory depression. DISCUSSION: Tramadol overdose was associated with a significant risk of seizures and respiratory depression in more severe cases, both which appear to be related to the ingested dose. There were no cases of serotonin toxicity, while opioid-like effects and adrenergic effects were prominent. CONCLUSION: Tramadol overdose is associated with seizures and respiratory depression, but is unlikely to cause serotonin toxicity.

[Serotonin syndrome and pain medication : What is relevant for practice?]. / Serotoninsyndrom und medikamentöse Schmerztherapie : Was ist für die Praxis relevant?

Serotonin syndrome is a dangerous and rare complication of a pharmacotherapy and can lead to death. Caused by unwanted interactions of serotonergic drugs, it is characterised by a neuroexcitatory triad of mental changes, neuromuscular hyperactivity and autonomic instability. Opioids with serotonergic effects include the phenylpiperidine series opioids fentanyl, methadone, meperidine and tramadol and the morphine analogues oxycodone and codeine. In combination with certain serotonergic drugs, e.g. antidepressants, they can provoke serotonin syndrome. In patients with such combinations, special attention should be paid to clinical signs of serotonergic hyperactivity. Higher risk combinations (e.g. monoamine oxidase inhibitors with tramadol) must be avoided. Treatment with serotonergic agents must be stopped in moderate or severe serotonin syndrome. Patients with a severe serotonin syndrome require symptomatic intensive care and specifically a pharmacological antagonism with cyproheptadine or chlorpromazine.

[The serotonin syndrome: why should cardiologists be aware and scared of it]. / Sindrome serotoninergica: perché anche il cardiologo la dovrebbe conoscere (e temere).

The serotonin syndrome (SS) represents a life-threatening adverse drug reaction, caused by serotonin overload in the central and peripheral nervous system, producing autonomic instability, neuromuscular and cardiovascular abnormalities, and cognitive alterations. The incidence of SS has been growing over the last few years, as a consequence of population aging and the steadily increasing use of pro-serotoninergic agents in clinical practice, in the presence of various comorbidities, mainly cardiovascular. Cardiologists often use combination therapies including serotoninergic agents, and should therefore consider the risk of serotoninergic adverse events caused by inappropriate drug interactions. SS is often difficult to diagnose and may be life-threatening if not adequately managed. Considering the several published case reports of overdose or not recommended associations, a greater awareness by clinicians about the potential risks associated with inappropriate use of these drugs is needed, as well as better information on the clinical features and therapeutic approaches to SS.

Serotonin syndrome following metaxalone overdose and therapeutic use of a selective serotonin reuptake inhibitor.

UNLABELLED: Metaxalone has only recently been associated with serotonin syndrome. The mechanism of action of this centrally acting muscle relaxant is unknown; however, the observation of serotonin syndrome in patients with metaxalone overdose suggests a role in the serotonergic pathway. CASE REPORT: (Case 1) A 29-year-old woman with overdose of metaxalone presented to the emergency department with altered mental status, seizure-like activity, hyperthermia, rigidity in the lower extremities, myoclonus, and hyperreflexia. Vital signs on arrival include blood pressure of 168/80 mmHg, heart rate of 208 beats per minute (bpm), respirations of 20/min, a temperature of 41.6° C rectally, and room air oxygen saturation of 97%. She was intubated and sedated with benzodiazepines, and actively cooled. Serum paroxetine concentration was 23 (therapeutic range: 20-200) ng/mL, and serum metaxalone concentration was 31 mcg/mL (peak plasma concentrations average 0.9 mcg/mL at 3.3 h following a single oral dose of 400 mg). (Case 2) A 27-year-old man presented to the emergency department with altered mental status, rigidity in his lower extremities, myoclonus, and hyperreflexia. Vital signs on arrival include blood pressure of 158/131 mmHg, heart rate of 126 bpm, respiratory rate of 20 breaths per minute, and temperature of 37.2°C, with oxygen saturation of 98% on room air. His medication list included metaxalone and escitalopram. He was managed aggressively with IV boluses of diazepam, in total 80 mg, in the emergency department. Serum escitalopram concentration was 24 ng/mL with a therapeutic range of 21-64 ng/mL, and serum metaxalone concentration was 58 mcg/mL. CONCLUSION: These two cases suggest that at supratherapeutic concentrations metaxalone has serotonergic effects. Severe serotonin toxicity may result from metaxalone abuse in individuals using a selective serotonin reuptake inhibitor therapeutically.