Successful treatment of serotonin syndrome with chlorpromazine

Adverse Clinical Effects Associated With Non-catecholamine Pharmacologic Agents for Treatment of Vasoplegic Syndrome in Adult Cardiac Surgery

Vasoplegic syndrome is a relatively common complication that can happen during and after major adult cardiac surgery. It is associated with a higher rate of complications, including postoperative renal failure, longer duration of mechanical ventilation, and intensive care unit stay, as well as increased mortality. The underlying pathophysiology of vasoplegic syndrome is that of profound vascular hyporesponsiveness, and involves a complex interplay among inflammatory cytokines, cellular surface receptors, and nitric oxide (NO) production. The pharmacotherapy approaches for the treatment of vasoplegia include medications that increase vascular smooth muscle contraction via increasing cytosolic calcium in myocytes, reduce the vascular effects of NO and inflammation, and increase the biosynthesis of and vascular response to norepinephrine. Clinical trials have demonstrated the clinical efficacy of non-catecholamine pharmacologic agents in the treatment of vasoplegic syndrome. With an increase in their use today, it is important for clinicians to understand the adverse clinical outcomes and patient risk profiles associated with these agents, which will allow better-tailored medical therapy.

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.

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.

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.

A case of the serotonin syndrome secondary to phenelzine monotherapy at therapeutic dosing

A 27-year-old Caucasian female with a history of depression was admitted to our local hospital with vague events that occurred a day before. This included an episode of dysarthria, and unsteadiness, followed by feeling generally unwell. Two weeks prior to presentation she was commenced on phenelzine. During clinical assessment she suddenly deteriorated with a dramatic fall in her conscious level. Moreover, she became hyperthermic, tachycardic, and diaphoretic, and developed increased tone in all muscles and ocular clonus. Rectal diazepam was administered but failed to control the symptoms. Consequently, she was transferred to the intensive care unit for intubation and muscle relaxants were commenced. She responded well and recovered next day without complications. Her symptoms and signs were consistent with the serotonin syndrome with phenelzine being the likely cause. To the best of our knowledge, this is the first reported case to associate the condition with phenelzine alone at therapeutic dose.

Serotonin syndrome after sertraline overdose in a child: a case report

Serotonin syndrome is a potentially life-threatening drug effect. It may be misdiagnosed because it has mostly been reported in adults. Case Report. An 8-year-old girl with behavioral problems and medicated with risperidone and sertraline was admitted in the emergency department after she had taken voluntarily 1500 mg of sertraline (50 mg/kg). At admission, she had marked agitation, visual hallucinations, diaphoresis, flushing, and tremor. She had fever and periods of hypertension. She also showed generalized rigidity and involuntary movements. She was treated with fluids and iv diazepam, midazolam, clemastine, and biperiden. As the patient presented a severe insomnia and a progressive rhabdomyolysis, she was transferred to pediatric intensive care unit (ICU), where she was under treatment with cyproheptadine, mechanical ventilation, and muscular paralysis for 11 days. She was discharged from hospital a few days later with no neurological sequelae. Conclusions. Serotonin syndrome is still not well recognized by physicians. In our patient, the diagnosis was made early due to the history of overdose with serotonin reuptake inhibitors and the triad of mental, neurological, and autonomic signs. Parents must be educated to prevent children from having free access to drugs, avoiding self-medication or overdose.

The serotonin syndrome-the need for physician's awareness

Background

Serotonin syndrome is a potentially life-threatening adverse drug reaction that results from therapeutic drug use, usually of selective serotonin reuptake inhibitors (SSRIs), intentional excessive use or interactions between various drugs.

Case presentation

A 16-year-old Caucasian boy presented to our emergency department (ED) with alteration in his mental status for 6 h prior to arrival. On physical examination in our ED, he was combative and disoriented to time, place and person. He was febrile, hypertensive and tachycardic as well. He had intermittent rigid extremities with myoclonus of both lower extremities. A diagnosis of serotonin syndrome (SS) was made based on history of intake of fluoxetine and clinical signs, which included presence of inducible clonus and agitation. The child received supportive care involving intravenous fluids and intravenous lorazepam. The child was back to his baseline mental status and had a normal neurological exam by 24 h and was discharged home later for follow-up with a psychiatrist.

Conclusions

SS occurs with increasing frequency, and most cases resolve with prompt recognition and supportive care. Failure to make an early diagnosis and to comprehend adverse pharmacological effects of therapy can lead to adverse outcomes.

Serotonin: a review

5-Hydroxytryptamine, or serotonin, is a biogenic amine most noted for its role as a neurotransmitter. Manipulation of serotonin in animal models was used as a tool for studying its role in humans. Through such research serotonin has been shown to modulate gastrointestinal motility, peripheral vascular tone, cerebral vascular tone, and platelet function and has been implicated in the pathophysiology of mood disorders, emesis, migraine, irritable bowel syndrome (IBS), and pulmonary and systemic hypertension. The knowledge gained is being directly applied back to animals in research on drugs that manipulate the serotonergic system in dogs and cats. Increasing use and availability of drugs that manipulate the serotonergic system has created a circumstance through which a novel toxicity was discovered in both humans and animals. Serotonin Syndrome describes the clinical picture seen in humans and animals with serotonin toxicity. This paper provides a review the physiology of serotonin and its involvement in the pathophysiologic mechanisms of various conditions, including the Serotonin Syndrome.

A systematic review of the serotonergic effects of mirtazapine in humans: implications for its dual action status

A systematic review of published work concerning mirtazapine was undertaken to assess possible evidence of serotonergic effects or serotonin toxicity (ST) in humans, because drug toxicity and interaction data from human over-doses is an useful source of information about the nature and potency of drug effects. There is a paucity of evidence for mirtazapine having effects on any indicator of serotonin elevation, which leads to an emphasis on ST as an important line of evidence. Mirtazapine is compared with its analogue mianserin, and other serotonergic drugs. Although mirtazapine is referred to as a dual-action 'noradrenergic and specific serotonergic drug' (NaSSA) little evidence to support that idea exists, except from initial microdialysis studies in animals showing small effects; those have not subsequently been replicated or substantiated by independent researchers. Also, new data indicate its affinity for Alpha 2 adrenoceptors is not different to mianserin. It appears to exhibit no serotonergic symptoms or toxicity in over-dose by itself, nor is there evidence that it precipitates ST in combination with monoamine oxidase inhibitors, as would be expected if it raises intra-synaptic serotonin levels. Mirtazapine has no demonstrable serotonergic effects in humans and there is insufficient evidence to designate it as a dual-action drug.

Monoamine oxidase inhibitors, opioid analgesics and serotonin toxicity

Toxicity resulting from excessive intra-synaptic serotonin, historically referred to as serotonin syndrome, is now understood to be an intra-synaptic serotonin concentration-related phenomenon. Recent research more clearly delineates serotonin toxicity as a discreet toxidrome characterized by clonus, hyper-reflexia, hyperthermia and agitation. Serotonergic side-effects occur with serotonergic drugs, and overdoses of serotonin re-uptake inhibitors (SRIs) frequently produce marked serotonergic side-effects, and in 15% of cases, moderate serotonergic toxicity, but not to a severe degree, which produces hyperthermia and risk of death. It is only combinations of serotonergic drugs acting by different mechanisms that are capable of raising intra-synaptic serotonin to a level that is life threatening. The combination that most commonly does this is a monoamine oxidase inhibitor (MAOI) drug combined with any SRI. There are a number of lesser-known drugs that are MAOIs, such as linezolid and moclobemide; and some opioid analgesics have serotonergic activity. These properties when combined can precipitate life threatening serotonin toxicity. Possibly preventable deaths are still occurring. Knowledge of the properties of these drugs will therefore help to ensure that problems can be avoided in most clinical situations, and treated appropriately (with 5-HT(2A) antagonists for severe cases) if they occur. The phenylpiperidine series opioids, pethidine (meperidine), tramadol, methadone and dextromethorphan and propoxyphene, appear to be weak serotonin re-uptake inhibitors and have all been involved in serotonin toxicity reactions with MAOIs (including some fatalities). Morphine, codeine, oxycodone and buprenorphine are known not to be SRIs, and do not precipitate serotonin toxicity with MAOIs.

A Comparison of the Pharmacokinetics of Oral and Sublingual Cyproheptadine

BACKGROUND

Cyproheptadine is reported to be effective in treating serotonin syndrome. It is only available as an oral preparation and administration after SSRI overdose treated with activated charcoal is problematic. Sublingual administration may circumvent this problem. The pharmacokinetics of sublingual cyproheptadine are not characterized. This study compares the pharmacokinetics of cyproheptadine following oral and sublingual administration.

METHODS

Cross-over, non-blinded, volunteer study using five healthy males. Eight milligrams of oral and sublingual cyproheptadine were administered on separate occasions with a one-week washout period. Sublingual arm subjects were pretreated with 50 g of oral activated charcoal 30 min prior to cyproheptadine, to prevent any gut absorption. Serum cyproheptadine concentration was measured at baseline, 30 min, and 1, 2, 3, 4, 6, 8, and 10 h by liquid chromatography and mass spectroscopy.

RESULTS

Mean C(max) for oral and sublingual were 30.0 microg/L and 4.0 microg/L respectively: mean T(max) were 4 h and 9.6 h; mean AUC were 209 and 25 microg x hr/L. Mean +/- SEM within-subject difference between oral and sublingual C(max) was 25.9 +/- 4.1 (p = 0.003) and AUC was 184 +/- 31 (p = 0.004).

CONCLUSIONS

Serum concentrations after sublingual cyproheptadine are significantly less than after oral administration. At these concentrations, the sublingual route is unlikely to be effective in treating serotonin syndrome.

Drug-induced hyperthermia and muscle rigidity: a practical approach

Body thermoregulation can be violently offset by drugs capable of altering the balance between heat production and dissipation. Such events may rapidly become fatal. The drugs that are involved in the eruption of such syndromes include inhalation anaesthetics, sympathomimetic agents, serotonin antagonists, antipsychotic agents and compounds that exhibit anticholinergic properties. The resultant hyperthermia is frequently accompanied by an intense skeletal muscle hypermetabolic reaction that leads to rapidly evolving rigidity, extensive rhabdomyolysis and hyperkalemia. The differential diagnosis should, however, rule out non-drug-induced causes, such as lethal catatonia, central nervous system infection or tetanus, strychnine poisoning, thyrotoxic storm and pheochromocytoma. Prompt life-saving procedures include aggressive body temperature reduction. Patients with a suspected drug (or non-drug) hypermetabolic reaction should be admitted into an intensive care area for close monitoring and system-oriented supportive treatment. We present six conditions, in decreasing order of gravity and potential lethality, in which hyperthermia plays an essential role, and suggest a clinical approach in such conditions.

The toxicity of antidepressant poisoning: is it changing? A comparative study of cyclic and newer serotonin-specific antidepressants

AIM

To compare the clinical features of cyclic antidepressant and newer, non-cyclic, serotonin-specific antidepressant poisoning.

METHODS

Comparitive, descriptive study of all antidepressant overdose patients admitted to a hospital toxicology service from February 1997 to April 2001. Patient data were entered prospectively into a dedicated toxicology database for subsequent analysis.

RESULTS

There were 256 admissions for antidepressant poisoning (17.5% of all poisoning admissions). Cyclic antidepressant poisoning comprised 43% of antidepressant admissions. Statistically significant differences between the two groups included: cyclic antidepressant group had longer median length of stay (23.1 vs 15.9 h, P = 0.0008), greater need for endotracheal intubation (31%vs 4%, OR = 11.5, P < 0.0001) and higher incidence of seizures (7.2%vs 0.7%, OR = 10.4, P = 0.01), faster median pulse rate, longer QRS-interval on admission, and longer intensive care unit stays. However, non-cyclic, serotonin-specific antidepressant poisonings involved larger doses of antidepressants and were more likely to ingest other medications along with these. Serotonin syndrome was only seen in non-cyclic, serotonin-specific poisoning (10.3%, OR = 26.6, P = 0.0002). Patients with serotonin syndrome had a longer median hospital stay (46 vs 16 h, P < 0.0002) compared to other non-cyclic, serotonin-specific patients. There were no deaths during the study period.

CONCLUSIONS

Cyclic antidepressants still comprise a significant proportion of antidepressant poisoning and result in more significant morbidity than non-cyclic, serotonin-specific poisoning. Clinicians should also be aware that non-cyclic, serotonin-specific poisoning may result in the development of serotonin syndrome. This was the most significant toxic effect noted following non-cyclic, serotonin-specific poisoning in this study.

Serotonin syndrome: early management with cyproheptadine

OBJECTIVE

To report a psychiatric patient who developed serotonin syndrome after a medication overdose and whose marked mydriasis was quickly reversed by administration of cyproheptadine. This phenomenon was confirmed when other cases of serotonin syndrome were studied.

METHOD

In the index patient as well as in three subsequent cases of serotonin syndrome, pupil diameter, muscle tone, mental status, and vital signs were monitored before and after a test dose of cyproheptadine as medications were discontinued and antiserotonergic therapy begun.

RESULTS

In each patient, cyproheptadine produced rapid reversal of mydriasis within one hour of the initial dose. Other signs of serotonin syndrome remitted more slowly. As the signs and symptoms of serotonin syndrome remitted and pupils returned to normal size and reactiveness, cyproheptadine therapy seemed to produce mydriasis after each dose. Cessation of therapy after this point did not result in recurrence of symptoms. One patient developed serotonin syndrome twice. Two patients developed serotonin syndrome during treatment with medications that are partial serotonin antagonists (mirtazapine and nefazodone).

CONCLUSIONS

Rapid reversal of mydriasis in serotonin syndrome by cyproheptadine may serve as a specific suppressive test for the condition, and possibly may add to our understanding of the syndrome. Treatment with cyproheptadine is not thought to abbreviate the illness, but provides symptomatic relief while symptoms persist.

Serotonin syndrome. Presentation of 2 cases and review of the literature

Serotonin syndrome is an underreported complication of pharmacotherapy that has been relatively ignored in the medical literature. We discuss 2 recent cases seen at our institution and 39 cases described in the English-language literature since 1995. We found that patients with serotonin syndrome most often (74.3%) presented within 24 hours of medication initiation, overdose, or change in dosage. The most common presenting symptoms and signs were confusion, agitation, diaphoresis, tachycardia, myoclonus, and hyperreflexia. The prevalences of hypertension, coma/unresponsiveness, seizures, and death were not as prominent in our study as previously reported, perhaps reflecting earlier recognition and intervention. The most common therapeutic intervention was supportive care alone (48% of patients). The use of 5-hydroxytryptamine (5-HT) antagonists such as cyproheptadine, however, has become more common and might reduce the duration of symptoms. Only 1 death occurred, and most patients (57.5%) had complete resolution of their symptoms within 24 hours of presentation. The increased use of serotonergic agents (alone and in combination) across multiple medical disciplines presents the possibility that the prevalence and clinical significance of this condition will rise in the future. Internists will need to be increasingly aware of and prepared for this pharmacologic complication. Prevention, early recognition of the clinical presentation, identification and removal of the offending agents, supportive care, and specific pharmacologic therapy are all important to the successful management of serotonin syndrome.

[Serotonin syndrome associated to the use of paroxetine. Case report]

We report on a case of serotonin syndrome associated to the use of the paroxetine, a serotonin reuptake inhibitor drug. Serotonin syndrome related to this drug not combined with other drugs had not yet been described in literature.

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 resulting from drug interactions

We describe six patients diagnosed with serotonin syndrome after exposure to drugs with serotonergic activity. Drug interactions occurred as a result of a combination of tricyclic antidepressants, selective serotonin reuptake inhibitors, selective noradrenaline reuptake inhibitors or monoamine oxidase inhibitors. Management included supportive care and the use of non-specific serotonin antagonists (cyproheptadine, benzodiazepines and chlorpromazine). All patients made uneventful recoveries.

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.

Treatment of the serotonin syndrome with cyproheptadine

The serotonin syndrome is the result of excess stimulation of central nervous 5-hydroxytryptamine (5HT)-1a and 5HT-2 receptors. The diagnosis requires a history of exposure to agents active at serotonin receptors and the presence of alterations in mental status, autonomic instability, and neuromuscular abnormalities such as tremor, hyperreflexia, or myoclonus. In this descriptive case series, five cases of serotonin syndrome are reported. All patients gave a history of recent exposure to one or more serotonergic medications, including moclobemide, paroxetine, sertraline, and venlafaxine, with clinical evidence of serotonin syndrome. All patients were administered cyproheptadine (4-8 mg orally) for serotonergic signs. Three had complete resolution of signs within 2 h of administration. Another two had a residual tremor or hyperreflexia following the first dose, which resolved following a repeat dose. There were no adverse outcomes from cyproheptadine use. The role of specific serotonin receptor antagonists such as cyproheptadine in the treatment of the serotonin syndrome remains to be delineated. Its use should be considered an adjunct to supportive care. Currently, it is unknown whether cyproheptadine modifies patient outcome.