Serotonin syndrome

Serotonin syndrome in a child associated with erythromycin and sertraline

Serotonin syndrome is an uncommon, serious adverse reaction that is usually associated with the interaction of two or more serotonergic agents. A 12-year-old boy receiving sertraline developed the syndrome after erythromycin was added to his regimen. The proposed mechanism involves erythromycin inactivation of cytochrome P450 3A4 inhibition of sertraline metabolism, accumulation of the drug, and precipitation of the syndrome. It is important for clinicians to consider both pharmacokinetic and pharmacodynamic interactions to minimize the risk of the reaction.

The serotonin syndrome and its treatment

Serotonin syndrome is caused by drug induced excess of intrasynaptic 5-hydroxytryptamine. The clinical manifestations are mediated by the action of 5-hydroxytryptamine on various subtypes of serotonin receptors. There is no effective drug treatment established. The history of the treatment of serotonin syndrome with 5-hydroxytryptamine blocking drugs is reviewed. A literature search was undertaken using both Medline and a manual search of the older literature. Reports of cases treated with the 5-HT2 blockers cyproheptadine and chlorpromazine were identified and analysed. There is some evidence suggesting the efficacy of chlorpromazine and cyproheptadine in the treatment of serotonin syndrome. The evidence for cyproheptadine is less substantial, perhaps because the dose of cyproheptadine necessary to ensure blockade of brain 5-HT2 receptors is 20-30 mg, which is higher than that used in the cases reported to date (4-16 mg).

Serotonin syndrome: history and risk

This review focuses on the history of investigations into the behavioural reaction resulting from excess stimulation of post-synaptic 5-hydroxytryptamine receptors and the relative risk of this occurring with different combinations of drugs. Other aspects, particularly treatment with 5-hydroxytryptamine receptor antagonists, are reviewed in a recent separate paper [44]. The first human case was in 1955 and animal work had defined the characteristic features by 1958, and established they were lessened by chlorpromazine. Substantial evidence of a 'dose-effect' relationship existed by 1984. The relative risk with different drug combinations is assessed from available evidence and argued to be strongly associated with the degree of elevation of 5-hydroxytryptamine, which is greatest following combinations of irreversible inhibitors of monoamine oxidase A and B with potent serotonin reuptake inhibitors. The various serotonergic drugs that may be implicated in serotonin syndrome are tabulated and discussed in relation to the relative risk. It is suggested that the proposed 'diagnostic criteria' for serotonin syndrome are inappropriate since there is a continuous spectrum from side effects to toxicity. The term 'serotonin syndrome' may encourage the presumption that it is an idiosyncratic response, as neuroleptic malignant syndrome is usually considered to be. The terms 'toxic serotomimetic reaction' or 'toxic serotonin syndrome' may be preferable alternatives. The differences between serotonin syndrome and neuroleptic malignant syndrome are highlighted with examples from difficult or questionable cases in the recent literature. It is proposed that more systematic national collection of toxicity data is essential in order to quantify the relative risk of serotonin syndrome with various combinations of serotonergic drugs.

Serotonin syndrome due to venlafaxine overdose

A case is presented of serotonin syndrome after deliberate overdose of the antidepressant venlafaxine. The mechanism, diagnosis, and management of this disorder is discussed.

Death by "ecstasy": the serotonin syndrome?

"Ecstasy" or 3,4-methylenedioxymethamphetamine (MDMA) is a popular drug of abuse and is generally regarded as safe by the lay public. There are an increasing number of reports of MDMA-induced toxicity that exhibit features of the serotonin syndrome. We report a case of severe hyperthermia, altered mental status, and autonomic dysfunction after a single recreational ingestion of MDMA.

SSRI-induced extrapyramidal side-effects and akathisia: implications for treatment

The selective serotonin reuptake inhibitors (SSRIs) may occasionally induce extrapyramidal side-effects (EPS) and/or akathisia. This may be a consequence of serotonergically-mediated inhibition of the dopaminergic system. Manifestations of these effects in patients may depend on predisposing factors such as the presence of psychomotor disturbance, a previous history of drug-induced akathisia and/or EPS, concurrent antidopaminergic and/or serotonergic therapy, recent monoamine oxidase inhibitor discontinuation, comorbid Parkinson's disease and possibly deficient cytochrome P450 (CYP) isoenzyme status. There is increasing awareness that there may be a distinct form of melancholic or endogenous depression with neurobiological underpinnings similar to those of disorders of the basal ganglia such as Parkinson's disease. Thus, it is not surprising that some individuals with depressive disorders appear to be susceptible to developing drug-induced EPS and/or akathisia. In addition, the propensity for the SSRIs to induce these effects in individual patients may vary within the drug class depending, for example, on their selectivity for serotonin relative to other monoamines, affinity for the 5-HT2C receptor, pharmacokinetic drug interaction potential with concomitantly administered neuroleptics and potential for accumulation due to a long half-life. The relative risk of EPS and akathisia associated with SSRIs have yet to be clearly established. The potential risks may be reduced by avoiding rapid and unnecessary dose titration. Furthermore, early recognition and appropriate management of EPS and/or akathisia is required to prevent the impact of these effects on patient compliance and subjective well-being. It is important that the rare occurrence of EPS in patients receiving SSRIs does not preclude their use in Parkinson's disease where their potentially significant role requires more systematic evaluation.

Medical causes of seizures

Seizures are commonly encountered in patients who do not have epilepsy. Factors that may provoke such seizures include organ failure, electrolyte imbalance, medication and medication withdrawal, and hypersensitive encephalopathy. There is usually one underlying cause, which may be reversible in some patients. A full assessment should be done to rule out primary neurological disease. Treatment of seizures in medically ill patients is aimed at correction of the underlying cause with appropriate short-term anticonvulsant medication. Phenytoin is ineffective in the management of seizures secondary to alcohol withdrawal, and in those due to theophylline or isoniazid toxicity. Control of blood pressure is important in patients with renal failure and seizures. Non-convulsive status epilepticus should be considered in any patient with confusion or coma of unclear cause, and electroencephalography should be done at the earliest opportunity. Most ill patients with secondary seizures do not have epilepsy, and this should be explained to patients and their families. Only those patients with recurrent seizures and uncorrectable predisposing factors need long-term treatment with anticonvulsant medication.

Serotonin syndrome after challenge with the 5-HT agonist meta-chlorophenylpiperazine

meta-Chlorophenylpiperazine (mCPP) is a non-selective 5-HT-receptor agonist/antagonist that is used extensively in psychiatry to assess central serotonergic function. We report on three patients who developed symptoms of the serotonin syndrome when they participated in an mCPP (0.5 mg/kg body weight p.o.) challenge test as part of a research protocol. They had relatively high plasma mCPP concentrations. The syndrome did not occur in normal volunteers who had comparable plasma concentrations of mCPP. Investigators should be aware of the possible occurrence of the serotonin syndrome after a single oral dose of mCPP.

Psychiatric and behavioral problems

In an emergency setting, many neurologic conditions present with psychiatric and behavioral symptoms. These symptoms may either be the first manifestation of the neurologic illness or a later occurrence in the progression of the disease. It is important for clinicians evaluating patients with psychiatric symptoms to identify the signs indicating associated neurologic illness and to have strategies for managing the acute, potentially dangerous, neuropsychiatric manifestations of the disease. This article addresses emergency evaluation and management of depression, anxiety, psychosis, mania, suicide attempts, neuroleptic malignant syndrome and other hypermetabolic and amnestic syndromes, somatoform disorders, aggression, and legal issues, such as capacity to accept or refuse treatment.

Antiparkinsonian Agents : Clinically Significant Drug Interactions and Adverse Effects, and Their Management

The treatment of Parkinson's disease for most patients entails long term exposure to multiple agents, including anticholinergics, levodopa, amantadine, dopamine receptor agonists, catechol-O-methyltransferase inhibitors, selegiline (deprenyl) and clozapine. Patients with Parkinson's disease require medication for the control of the motor symptoms of their condition, for related medical or psychiatric symptoms of the disorder, and for concurrent medical problems, such as hypertension or cardiac disease.All these agents may cause adverse effects. There is a potential for drug-drug interactions between different antiparkinsonian agents and between antiparkinsonian medication and the other drugs a patient may be taking. Clinicians caring for patients with Parkinson's disease must be knowledgable about the potential adverse effects and drug interactions of an expanding array of medications for this condition.

Severe hyperthermia during tetrabenazine therapy for tardive dyskinesia

We recently observed a 45-year-old patient with a history of psychiatric illness who presented with severe hyperthermia (rectal temperature above 41 degrees C) with intense rhabdomyolysis and liver cytolysis during tetrabenazine therapy for neuroleptic tardive dyskinesia. In addition to tetrabenazine, this patient took lorazepam and two antidepressant drugs: clomipramine, a potent serotonin-reuptake inhibitor, and mianserin. Hyperthermia responded to parenteral sodium dantrolene and oral bromocriptine administration. The significant role of tetrabenazine (a central nervous system dopamine-depleting drug) and the contribution of antidepressants to the mechanism of this neuroleptic malignant syndrome - like hyperthermia are discussed.

Neuroleptic malignant syndrome in the acquired immunodeficiency syndrome

Patients infected by the human immunodeficiency virus are predisposed to many infectious and noninfectious complications and often receive a variety of drugs. Furthermore, they seem to have a particular susceptibility to idiosyncratic adverse drug reactions. It is therefore surprising that only a few cases of the neuroleptic malignant syndrome have been described in patients with the acquired immunodeficiency syndrome. A high index of suspicion is required to diagnose the neuroleptic malignant syndrome in these patients, as its usual manifestations, including fever and altered consciousness, are frequently attributed to an underlying infection.

Serotonin syndrome. A clinical update

Serotonin syndrome is characterized by varied degrees of cognitive, autonomic, and neuromuscular dysfunction and can only be produced by drug therapy that increases central nervous system serotonin neurotransmission. Information gained from a retrospective review of 127 cases of serotonin syndrome is presented. It is not uncommon for severe cases of serotonin syndrome to be confused with neuroleptic malignant syndrome. Treatment is mainly supportive, but specific pharmacologic therapy with serotonin antagonists may be potentially beneficial.

The serotonin syndrome

The serotonin syndrome is characterized by mental status changes and a variety of autonomic and neuromuscular manifestations. Its duration is usually brief, resolving within hours provided that the inciting agent has been discontinued. In most cases, two or more types of medications known to increase the activity of serotonin at the 5-HT1A receptor are required to produce it, and it frequently begins soon after the initiation of a new treatment regimen. Treatment is largely supportive although limited clinical experience warrants the cautious use of specified agents. Although its overall incidence is unknown, it is probably low, and an appropriate level of suspicion coupled with an adequate knowledge of the patient's drug history remains the mainstay of diagnosis and treatment.

Myoglobinuria, malignant hyperthermia, neuroleptic malignant syndrome and serotonin syndrome

This article presents an overview of the causes and manifestations of myoglobinuria and provides criteria for its diagnosis and management. The article also reviews neuroleptic malignant syndrome, malignant hyperthermia, and serotonin syndrome, all of which could cause rhabdomyolysis and myoglobinuria.

Recurrent near-syncope with flushing

Episodic vasomotor instability with flushing is an uncommon presentation that is suggestive of an endocrine etiology. This report is the case of a 42-year-old woman who presented to the ED 5 times in a 2-week period for recurrent, self-limited episodes of light-headedness associated with tachycardia, hypertension, and flushing. The patient's diagnosis eluded detection in both the outpatient and the inpatient settings for several months. The clinical diagnosis was ultimately confirmed by biochemical test samples obtained in the ED during a subsequent symptomatic event. The differential diagnosis of this patient's presentation includes pheochromocytoma, carcinoid syndrome, medullary thyroid carcinoma, systemic mastocytosis, and other endocrine and toxicologic diseases. ED management of the patient with transient yet significant vasomotor changes includes a workup for syncope, initiation of focused biochemical investigations, referral to the appropriate consultant, and consideration for admission.

Selective serotonin reuptake inhibitor-induced serotonin syndrome: review

The selective pharmacology of the selective serotonin reuptake inhibitors (SSRIs) results in a lower potential for pharmacodynamic drug interactions relative to other antidepressants such as the tricyclic antidepressants (TCAs) and monoamine oxidase inhibitors (MAOIs). However, the SSRIs have been implicated in the development of the serotonin syndrome--a potentially life-threatening complication of treatment with psychotropic drugs. The syndrome is produced most often by the concurrent use of two or more drugs that enhance central nervous system serotonin activity and often goes unrecognized because of the varied and nonspecific nature of its clinical features. The serotonin syndrome is characterized by alterations in cognition (disorientation, confusion), behavior (agitation, restlessness), autonomic nervous system function (fever, shivering, diaphoresis, diarrhea), and neuromuscular (ataxia, hyperreflexia, myoclonus) activity. The difference between this syndrome and the occurrence of adverse effects caused by serotonin reuptake inhibitors alone is the clustering of the signs and symptoms, their severity, and their duration. There are important pharmacokinetic interactions between SSRIs and other serotonergic drugs due principally to their effects on the cytochrome P450(CYP) isoenzymes, the potential for which varies widely amongst the SSRI group, which may increase the likelihood of a pharmacodynamic interaction. The exceptionally long washout period required after fluoxetine discontinuation may cause additional problems and/or inconvenience. Patients with serotonin syndrome usually respond to discontinuation of drug therapy and supportive care alone, but they may also require treatment with antiserotonergic agent such as cyproheptadine, methysergide, and/or propranolol. To reduce the occurrence, morbidity, and mortality of the serotonin syndrome, it must be both prevented by prudent pharmacotherapy and given prompt recognition when it is present.

[123I]beta-CIT single-photon emission tomography in DOPA-responsive dystonia

The radiotracer [123I]beta-CIT is a sensitive marker of dopamine uptake sites that can be used to visualize dopaminergic nerve endings in vivo in the human brain. We report on [123I]beta-CIT single-photon emission computed tomography (SPECT) findings in a patient with DOPA-responsive dystonia (DRD). [123I]beta-CIT SPECT showed a striatal radiotracer uptake in the upper range of normal, indicating intact dopamine transporters and structural integrity of nigrostriatal neurons. This differentiates DRD from clinically similar cases with juvenile-onset parkinsonism with dystonia that have a considerable poorer prognosis. [123I]-beta-CIT SPECT may provide a method equally as useful as fluorodopa positron emission tomography in DRD.

Catastrophic Consequences Secondary to Psychotropic Drugs, Part 1

The use of psychotropic drugs has dramatically changed the lives of many; yet as often occurs with technological advances, negative outcomes can be encountered. Potentially fatal reactions to neuroleptic drugs and serotonin-enhancing agents (e.g., antidepressants) have been presented in Part 1, with the intent of alerting and informing psychiatric nurses. Part 2 will complete this series on catastrophic consequences of psychotropic drugs with a discussion of agranulocytosis and lithium toxicity.

Headache induced by serotonergic agonists--a key to the interpretation of migraine pathogenesis?

Serotonergic agonists such as m-chlorophenylpiperazine (m-CPP) and fenfluramine may induce migraine attacks. This has led to opposing theories concerning the role of 5-hydroxytryptamine (5HT) in triggering migraine attacks; is there hyperfunction or hypofunction of the central serotonergic system. Our review of the literature strongly suggests that m-CPP and fenfluramine provoke migraine attacks by stimulating, directly or indirectly, the 5HT2C/5HT2B receptors, although there is no total agreement with this interpretation. Central 5HT hypersensitivity in migraine patients, probably due to 5HT neuronal depletion, is proposed on the basis of review of electrophysiological tests and neuroendocrine challenge paradigms.

Possible serotonin syndrome associated with tramadol and sertraline coadministration

OBJECTIVE

To report a possible case of serotonin syndrome associated with coadministration of tramadol hydrochloride and sertraline hydrochloride.

CASE SUMMARY

A 42-year-old woman developed atypical chest pain, sinus tachycardia, confusion, psychosis, sundowning, agitation, diaphoresis, and tremor. She was taking multiple medications, including tramadol and sertraline. The tramadol dosage had recently been increased, resulting in what was believed to be serotonergic syndrome.

DISCUSSION

Serotonin syndrome is a toxic hyperserotonergic state that develops soon after initiation or dosage increments of the offending agent. Patients may differ in their susceptibility to the development of serotonin syndrome. The (+) enantiomer of tramadol inhibits serotonin uptake. Tramadol is metabolized to an active metabolite, M1, by the CYP2D6 enzyme. If this metabolite has less serotonergic activity than tramadol, inhibition of CYP2D6 by sertraline could have been a factor in the interaction.

CONCLUSIONS

Clinicians should be aware of the potential for serotonin syndrome with concomitant administration of sertraline and tramadol.

Citalopram overdose--review of cases treated in Swedish hospitals

BACKGROUND

The toxic effects of acute citalopram overdose are reported by the Swedish Poisons Information Centre.

DESIGN

Case reports received from Swedish hospitals during 1995 have been analyzed. Forty-four cases of pure citalopram intoxication have been studied in detail.

RESULTS

At doses below 600 mg, mild symptoms were observed. Doses above 600 mg caused ECG abnormalities and convulsions in some patients, while doses greater than 1900 mg caused such symptoms in all patients.

CONCLUSIONS

The findings are consistent with previous reports claiming that selective serotonin reuptake inhibitors are less toxic compared to tricyclic antidepressants. However, there is a risk of developing serious symptoms when large doses have been ingested.

Brainstem encephalopathy with stimulus-sensitive myoclonus leading to respiratory arrest, but with recovery: a description of two cases and review of the literature

Two unrelated patients developed bulbar symptoms, followed within several weeks by spontaneous myoclonus and painful, generalized, stimulus-sensitive jerks triggered by unexpected noises and cutaneous stimuli. They progressed to respiratory arrest and required mechanical ventilation, but both patients subsequently made an almost full recovery. These cases stress the importance of persevering with supportive treatment despite rapid progression of this severe generalized movement disorder. The relationship of brainstem reflex myoclonus to hyperekplexia, progressive encephalomyelitis with rigidity, and the stiff-man syndrome is discussed.

Serotonin syndrome complicating migraine pharmacotherapy

Serotonin syndrome, a condition with numerous clinical neurological manifestations, is the result of central serotonergic hyperstimulation. Features of the syndrome include mental status and behavioral changes (agitation, excitement, hypomania, obtundation), motor system involvement (myoclonus, hemiballismus, tremor, hyperreflexia, motor weakness, dysarthria, ataxia) and autonomic symptoms (fever, chills, diarrhea). Serotonin syndrome has been reported exclusively in patients on medications for psychiatric illness and Parkinsonism, despite the fact that the putative action of many antimigraine agents also involves the serotonin system. We herein report six patients with migraine who developed symptoms suggestive of the serotonin syndrome. Five were taking one or more serotomimetic agents for migraine prophylaxis (sertraline, paroxetine, lithium, imipramine, amitriptyline). In each case the symptoms and signs developed in close temporal proximity with use of a migraine abortive agent known to interact with serotonin receptors. In three instances the agent was subcutaneous sumatriptan and, in three, intravenous dihydroergotamine. In each instance the symptoms were transient and there was full recovery. With the ever increasing use of migraine medications active at serotonin receptor sites, cases of serotonin syndrome will likely occur more frequently. It is important that physicians treating migraine are aware of the serotonin syndrome and are able to recognize its varying presentations.

[Serotonin syndrome in acute poisoning with antidepressive agents]

We report a case of severe serotonin syndrome after self-poisoning with two antidepressant drugs, paroxetine (a selective inhibitor of serotonin reuptake) and moclobemide (a reversible inhibitor of MAO-A). The serotonin syndrome is characterized by neuromuscular, behavioural, and autonomic changes. It occurs with the use of drugs able to increase serotonergic transmission in brain by acting on biosynthesis, reuptake, catabolism or release of serotonin. Treatment is symptomatic. The incidence of severe cases seems to have increased, probably due to the use of new antidepressant "specific" inhibitors of the serotonin reuptake.

Neurotransmitters in CSF of idiopathic adult-onset dystonia: reduced 5-HIAA levels as evidence of impaired serotonergic metabolism

While several radiological findings point towards the basal ganglia as a possible anatomical site of the lesion in dystonia patients the biochemical basis of the disorder is still unknown. 5-Hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA) levels-the respective metabolites of serotonin and dopamine-were measured in lumbar cerebrospinal fluid (lCSF) of 15 patients with idiopathic adult-onset focal dystonia and in lCSF of 11 controls. 100 microliters lCSF were analyzed for 5-HIAA and HVA by reversed-phase HPLC with electrochemical detection. 5-HIAA levels were significantly reduced in dystonia patients (11.4 micrograms/ml) compared to controls (18.4 ng/ml) (p < 0.02). HVA levels in dystonia patients (30.3 ng/ml) were below control values (41.6 ng/ml) but this finding did not reach statistical significance. Decreased lCSF levels of 5-HIAA suggest an impaired serotonin metabolism in patients with idiopathic adult-onset dystonia. This observation may provide a biochemical basis for a more specific pharmacotherapy in dystonia patients.

The depressions of Alzheimer's disease: sorting, pharmacotherapy, and clinical advice

Research describing wide prevalence variation of Alzheimer's disease (AD) and comorbid depression is explained in light of subsyndromal depressions, the use of standardized diagnostic instruments and procedures, and the subcortical and cortical components of mood. There appear to be several "depressions" of AD. Against this backdrop, double-blind, placebo-controlled studies of antidepressant use in AD are reviewed and methodologic problems identified. Evidence for efficacy in controlled trials is weak, but open-label trials are, as expected, more encouraging. The potential efficacy of new agents for the depressions of AD receive comment. A heuristic model makes use of the conclusions developed, the stage of illness, and a preliminary classification scheme for the depressions of AD; this model provides a rational basis for thinking about medication selection for AD depressions. Clinical decisions are illustrated.