Serotonin Syndrome with Elevated Paroxetine Concentrations

Increased Brain Serotonin Rather Than Increased Blood Acetaldehyde as a Common Denominator Behind Alleged Disulfiram-Like Reactions

Several pharmaceutical agents are known to produce ethanol intolerance, which is often depicted as disulfiram-like reaction. As in the case with disulfiram, the underlying mechanism is believed to be the accumulation of acetaldehyde in the blood, due to inhibition of the hepatic aldehyde dehydrogenases, albeit this has not been confirmed in all cases by blood acetaldehyde measurements. Herein, cefamandole, cotrimoxazole, griseofulvin, procarbazine, and propranolol, which are reported to produce a disulfiram-like reaction, as well as disulfiram, were administered to Wistar rats and the hepatic activities of ethanol metabolizing enzymes along with the levels of brain monoamines were determined. Blood acetaldehyde was also evaluated after ethanol administration in rats pretreated with the abovementioned pharmaceutical products. Disulfiram, cefamandole, and procarbazine significantly increased blood acetaldehyde levels after ethanol administration, while on the contrary, cotrimoxazole, griseofulvin, and propranolol had no effect on blood acetaldehyde. Interestingly, all substances used, except disulfiram, increased the levels of brain serotonin. According to our findings, cotrimoxazole, griseofulvin, and propranolol do not produce a typical disulfiram-like reaction, because they do not increase blood acetaldehyde when given together with ethanol. On the other hand, all tested agents share the common property to enhance brain serotonin, whereas a respective effect of ethanol is well established. Hence, the ethanol intolerance produced by these agents, whether blood acetaldehyde concentration is elevated or not, could be the result of a “toxic serotonin syndrome,” as in the case of the concomitant use of serotonin-active medications that provoke clinical manifestations similar to those of a disulfiram reaction.

A Case Report of Serotonin Syndrome in a Patient on Selective Serotonin Reuptake Inhibitor (SSRI) Monotherapy

INTRODUCTION

Paroxetine is a selective serotonin reuptake inhibitor (SSRI) with several indications, one of which is for depression. We present a case of probable paroxetine-induced serotonin syndrome.

CASE SUMMARY

A 21-year-old female with a history of generalized anxiety disorder and major depression presented with increased depressive symptoms over several months while taking fluoxetine 20 mg daily. Fluoxetine was discontinued without taper and replaced with paroxetine 10 mg daily, along with hydroxyzine 50 mg twice daily as needed for anxiety. Within a week of starting the paroxetine, the patient reported increased anxiety, insomnia, and constant shaking. The paroxetine continued to be uptitrated over a 3-week period to a dose 30 mg due to unremitting depressive symptoms. One month later, the patient presented with tachycardia, generalized body aches, extreme fatigue, weakness, uncontrollable twitching, tremor, and hyperreflexia. A widespread burning sensation accompanied by random hot flashes without diaphoresis was also noted. Serotonin syndrome was diagnosed using the Hunters criteria. Paroxetine was discontinued, and the patient's physical symptoms resolved within a week.

DISCUSSION

To date, only 5 cases of serotonin syndrome have been reported in patients receiving SSRI monotherapy at recommended therapeutic doses.

Management of severe arterial hypertension associated with serotonin syndrome: a case report analysis based on systematic review techniques

Serotonin syndrome is thought to arise from serotonin excess. In many cases, symptoms are mild and self-limiting. But serotonin syndrome can become life threatening, when neuromuscular hyperexcitability spins out of control. Uncontainable neuromuscular hyperexcitability may lead to cardiovascular complications, linked to extreme changes in blood pressure. Currently, there is little guidance on how to control blood pressure in hyperserotonergic states. We report a case with treatment-resistant arterial hypertension, followed by a clinical review (using systematic review principles and techniques) of the available evidence from case reports published between 2004 and 2016 to identify measures to control arterial hypertension associated with serotonin syndrome. We conclude that classic antihypertensives may not be effective for the treatment of severe hypertension associated with serotonin syndrome. Benzodiazepines may lower blood pressure. Patients with severe hypertension not responding to benzodiazepines may benefit from cyproheptadine, propofol or both. In severe cases, higher cyproheptadine doses than currently recommended may be necessary.

Rare case of severe serotonin syndrome leading to bilateral compartment syndrome

The term 'serotonin syndrome' describes a constellation of symptoms caused by serotonergic overstimulation. Its characteristic clinical presentation consists of encephalopathy, neuromuscular signs and autonomic hyperactivity. After removal of the offending agent, the clinical course is usually self-limited but can occasionally lead to severe symptoms. We report the case of a 68-year-old woman who presented emergently with encephalopathy. Home medications included paroxetine and dextroamphetamine/amphetamine. Physical examination revealed tachycardia, tachypnoea, diaphoresis, rigidity, hyperreflexia and clonus. Given the fast onset of symptoms, a diagnosis of serotonin syndrome was made. Laboratory studies showed acute-on-chronic kidney injury and elevated creatine kinase. The patient's mental status quickly returned to baseline with supportive care. Her rhabdomyolysis, however, persisted and led to acute compartment syndrome in her lower extremities. After bilateral leg fasciotomies and treatment of a severe wound infection with intravenous antibiotics, the patient has now recovered with complete resolution of her symptoms.

Pharmaceutical Agents Known to Produce Disulfiram-Like Reaction: Effects on Hepatic Ethanol Metabolism and Brain Monoamines

Several pharmaceutical agents produce ethanol intolerance, which is often depicted as disulfiram-like reaction. As in the case with disulfiram, the underlying mechanism is believed to be the accumulation of acetaldehyde in the blood, due to inhibition of the hepatic aldehyde dehydrogenases. In the present study, chloramphenicol, furazolidone, metronidazole, and quinacrine, which are reported to produce a disulfiram-like reaction, as well as disulfiram, were administered to Wistar rats and the hepatic activities of alcohol and aldehyde dehydrogenases (1A1 and 2) were determined. The expression of aldehyde dehydrogenase 2 was further assessed by Western blot analysis, while the levels of brain monoamines were also analyzed. Finally, blood acetaldehyde was evaluated after ethanol administration in rats pretreated with disulfiram, chloramphenicol, or quinacrine. The activity of aldehyde dehydrogenase 2 was inhibited by disulfiram, chloramphenicol, and furazolidone, but not by metronidazole or quinacrine. In addition, although well known for metronidazole, quinacrine also did not increase blood acetaldehyde after ethanol administration. The protein expression of aldehyde dehydrogenase 2 was not affected at all. Interestingly, all substances used, except disulfiram, increased the levels of brain serotonin. According to our findings, metronidazole and quinacrine do not produce a typical disulfiram-like reaction, because they do not inhibit hepatic aldehyde dehydrogenase nor increase blood acetaldehyde. Moreover, all tested agents share the common property to enhance brain serotonin, whereas a respective effect of ethanol is well established. Therefore, the ethanol intolerance produced by these agents, either aldehyde dehydrogenase is inhibited or not, could be the result of a “toxic serotonin syndrome,” as in the case of the concomitant use of serotonin-active medications.

Case reports of neuroleptic malignant syndrome in context of quetiapine use

A retrospective analysis was followed on 20 case reports covering the possible correlation between the atypical antipsychotic, quetiapine, and neuroleptic malignant syndrome (NMS), determined by the study of 7 different NMS criteria guidelines. A great majority (19) of the case studies did not meet the requirements of all 7 guidelines, frequently due to unreported information. Nor was quetiapine proven to be the sole cause of the possible NMS in the two age groups investigated. Only one case was found to have no other medication or medical conditions confounding the relationship of quetiapine and NMS symptoms, and that case was in the context of a significant quetiapine overdose. The other 19 cases demonstrated the difficulty of identifying the cause of NMS when polypharmacy and other medical conditions are involved. The authors note the need for caution in deciding both the presence of NMS and the causal factors of the symptoms.

Misuse of the Naranjo Adverse Drug Reaction Probability Scale in toxicology

CONTEXT

When an adverse event occurs in an overdose patient, it may be difficult to determine whether the event was caused by the ingested drug or by medical therapy. Naranjo et al. developed a probability scale, the Naranjo Adverse Drug Reaction Probability Scale (Naranjo Scale), to assess the probability that a drug administered in therapeutic doses caused an adverse event thereby classifying the event as an adverse drug reaction (ADR). Although Naranjo et al. specifically excluded the application of this scale to adverse events in overdose patients, case reports demonstrate that authors continue to apply the Naranjo Scale to events in these patients.

OBJECTIVE

The World Health Organization defines an ADR as occurring only when drugs are administered in therapeutic doses. Yet ADRs continue to be reported in overdose patients. We sought to examine the use of the Naranjo scale in case reports of overdose patients to assess the potential consequences of that application.

METHODS

A Medline search via PubMed without language limits, through September 2012, using the search terms "Naranjo" and "overdose" or "poisoning" yielded 146 publications. Additional searches were performed to find articles with keywords of the Naranjo Scale development, current applications and validity of application in specific populations such as critically ill and overdose patients.

RESULTS

From the 146 publications, we identified 17 case reports or case series of overdose patients in which the Naranjo Scale was applied to a clinical complication to support a causal relationship between an administered drug and the clinical complication and thereby classify the clinical complication as an ADR. We also identified a recent publication in which the Naranjo Scale was applied to a new treatment modality (lipid emulsion) that is currently administered to overdose patients. Original publication of the Naranjo Scale and studies evaluating its use in critically ill patients or those with drug-induced disease were also retrieved.

CONCLUSION

Adverse events that occur in overdose patients are excluded from the definition of ADR. Yet in case reports or series of overdose patients, the Naranjo Scale has been applied to assess the probability an event was caused by the ingested drug or therapeutic modality. This application of the Naranjo Scale is not scientifically valid and may lead to erroneous conclusions. There is no evidence to support the application of the Naranjo scale to any events that occur in overdose patients.

Selective serotonin reuptake inhibitor poisoning: An evidence-based consensus guideline for out-of-hospital management

A review of US poison center data for 2004 showed over 48,000 exposures to selective serotonin reuptake inhibitors (SSRIs). A guideline that determines the conditions for emergency department referral and prehospital care could potentially optimize patient outcome, avoid unnecessary emergency department visits, reduce health care costs, and reduce life disruption for patients and caregivers. An evidence-based expert consensus process was used to create the guideline. Relevant articles were abstracted by a trained physician researcher. The first draft of the guideline was created by the lead author. The entire panel discussed and refined the guideline before distribution to secondary reviewers for comment. The panel then made changes based on the secondary review comments. The objective of this guideline is to assist poison center personnel in the appropriate out-of-hospital triage and initial management of patients with a suspected ingestion of an SSRI by 1) describing the process by which an ingestion of an SSRI might be managed, 2) identifying the key decision elements in managing cases of SSRI ingestion, 3) providing clear and practical recommendations that reflect the current state of knowledge, and 4) identifying needs for research. This guideline applies to ingestion of immediate-release forms of SSRIs alone. Co-ingestion of additional substances might require different referral and management recommendations depending on their combined toxicities. This guideline is based on an assessment of current scientific and clinical information. The expert consensus panel recognizes that specific patient care decisions may be at variance with this guideline and are the prerogative of the patient and the health professionals providing care, considering all of the circumstances involved. This guideline does not substitute for clinical judgment. Recommendations are in chronological order of likely clinical use. The grade of recommendation is in parentheses. 1) All patients with suicidal intent, intentional abuse, or in cases in which a malicious intent is suspected (e.g., child abuse or neglect) should be referred to an emergency department. This activity should be guided by local poison center procedures. In general, this should occur regardless of the dose reported (Grade D). 2) Any patient already experiencing any symptoms other than mild effects (mild effects include vomiting, somnolence [lightly sedated and arousable with speaking voice or light touch], mydriasis, or diaphoresis) should be transported to an emergency department. Transportation via ambulance should be considered based on the condition of the patient and the length of time it will take the patient to arrive at the emergency department (Grade D). 3) Asymptomatic patients or those with mild effects (defined above) following isolated unintentional acute SSRI ingestions of up to five times an initial adult therapeutic dose (i.e., citalopram 100 mg, escitalopram 50 mg, fluoxetine 100 mg, fluvoxamine 250 mg, paroxetine 100 mg, sertraline 250 mg) can be observed at home with instructions to call the poison center back if symptoms develop. For patients already on an SSRI, those with ingestion of up to five times their own single therapeutic dose can be observed at home with instructions to call the poison center back if symptoms develop (Grade D). 4) The poison center should consider making follow-up calls during the first 8 hours after ingestion, following its normal procedure. Consideration should be given to the time of day when home observation will take place. Observation during normal sleep hours might not reliably identify the onset of toxicity. Depending on local poison center policy, patients could be referred to an emergency department if the observation would take place during normal sleeping hours of the patient or caretaker (Grade D). 5) Do not induce emesis (Grade C). 6) The use of oral activated charcoal can be considered since the likelihood of SSRI-induced loss of consciousness or seizures is small. However, there are no data to suggest a specific clinical benefit. The routine use of out-of-hospital oral activated charcoal in patients with unintentional SSRI overdose cannot be advocated at this time (Grade C). 7) Use intravenous benzodiazepines for seizures and benzodiazepines and external cooling measures for hyperthermia (>104 degrees F [>40 degrees C]) for SSRI-induced serotonin syndrome. This should be done in consultation with and authorized by EMS medical direction, by a written treatment protocol or policy, or with direct medical oversight (Grade C).

Mechanism of paroxetine-induced cell death in renal tubular cells

Paroxetine belongs to the family of selective serotonin reuptake inhibitors. Much research has been performed on the in vitro effect of paroxetine; however, the effect of paroxetine on Madin-Darby canine kidney renal tubular cells is unknown. The present study was aimed at exploring how paroxetine affects viability and to examine the underlying mechanisms. Paroxetine (15-200 microM) was shown to reduce cell viability via inducing apoptosis in a concentration-dependent manner. Paroxetine-induced cytotoxicity and apoptosis were not changed by the p38 mitogen-activated protein kinase inhibitor SB203580 and the c-Jun NH2-terminal kinase inhibitor SP600125, but was potentiated by the extracellular signal-regulated kinase inhibitor PD98059; inhibited by GF 109203X, a protein kinase C inhibitor; and potentiated by phorbol 12-myristate 13-acetate, a protein kinase C activator. Paroxetine induced [Ca2+](i) rises; however, pre-treatment with 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetra(acetoxymethyl)ester, a Ca2+ chelator, to prevent 20 microM paroxetine-induced [Ca2+](i) rises did not protect cells from death. H-89 (a protein kinase A inhibitor) and U73122 (a phospholipase C inhibitor) failed to alter paroxetine-induced cell death. The results suggest that in Madin-Darby canine kidney cells, paroxetine caused protein kinase C-dependent, Ca2+-independent apoptosis which was potentiated by inhibition of the extracellular signal-regulated kinase pathway.

Rare case of serotonin syndrome with therapeutic doses of paroxetine

Paroxetine (Paxil) is a selective serotonin reuptake inhibitor (SSRI) and anxiolytic that is approved to treat numerous mood disorders. Serotonin syndrome, defined as a triad of mental status changes, autonomic instability, and neuromuscular abnormalities, is a potentially life-threatening complication of administering such serotonin-modifying drugs. Most cases of serotonin syndrome that have occurred with paroxetine administration are due to inadvertent drug interactions, most notably between SSRIs and monamine oxidase inhibitors, or intentional overdoses. The authors present the case of an 80-year-old woman who presented with serotonin syndrome while on a therapeutic dose of paroxetine. Paroxetine was stopped, and aggressive hydration with fluids and treatment with cyproheptadine was followed by remarkable improvement and return to baseline status in 4 days. This case illustrates the importance for physicians to have a heightened sense of suspicion of the serotonin syndrome in any patient known to be on serotonin-modifying agents presenting with altered sensorium and cholinergic symptoms. Consequently, they will be able to start timely treatment without subjecting the patient to unnecessary and potentially harmful tests.

Paroxetine-induced apoptosis in human osteosarcoma cells: activation of p38 MAP kinase and caspase-3 pathways without involvement of [Ca2+]i elevation

Selective serotonin reuptake inhibitors (SSRIs), a group of antidepressants, are generally used for treatment of various mood and anxiety disorders. There has been much research showing the anti-tumor and cytotoxic activities of some antidepressants; but the detailed mechanisms were unclear. In cultured human osteosarcoma cells (MG63), paroxetine reduced cell viability in a concentration- and time-dependent manner. Paroxetine caused apoptosis as assessed by propidium iodide-stained cells and increased caspase-3 activation. Although immunoblotting data revealed that paroxetine could activate the phosphorylation of extracellular signal-regulated kinase (ERK), c-Jun NH(2)-terminal kinase (JNK) and p38 mitogen-activated protein kinase (p38 MAPK), only SB203580 (a p38 MAPK inhibitor) partially prevented cells from apoptosis. Paroxetine also induced [Ca(2+)](i) increases which involved the mobilization of intracellular Ca(2+) stored in the endoplasmic reticulum and Ca(2+) influx from extracellular medium. However, pretreatment with BAPTA/AM, a Ca(2+) chelator, to prevent paroxetine-induced [Ca(2+)](i) increases did not protect cells from death. The results suggest that in MG63 cells, paroxetine caused Ca(2+)-independent apoptosis via inducing p38 MAPK-associated caspase-3 activation.

Paroxetine overdose

Paroxetine is a commonly used antidepressant with a safe side-effect profile. A case of paroxetine overdose (560 mg) is reported in an 18-year-old female who attempted suicide and recovered without any sequelae, requiring only supportive treatment. This report highlights a case of pure paroxetine overdose and the safety profile of paroxetine in overdose.

Serotonin Toxicity Associated with Concomitant Use of Linezolid

OBJECTIVE:

To report 2 cases of serotonin toxicity (ST) associated with concomitant use of linezolid and serotonergic drugs and review previously published case reports.

CASE SUMMARIES:

Case 1. A 38-year-old white female with cystic fibrosis treated with venlafaxine 300 mg/day for one year was prescribed linezolid 600 mg intravenously every 12 hours for treatment of methicillin-resistant Staphylococcus aureus (MRSA) pulmonary infection. She displayed symptoms of ST 8 days after the introduction of linezolid. The venlafaxine dosage was decreased to 150 mg/day, and symptoms gradually abated over 36 hours. Case 2. A 37-year-old male with multiple myeloma received citalopram 40 mg/day and trazodone 150 mg/day for anxiety-related disorders. Linezolid treatment with 600 mg orally twice daily was instituted for MRSA cellulitis. The following day, the patient developed anxiety, panic attacks, tremors, tachycardia, and hypertension that persisted throughout linezolid treatment. Symptoms finally waned 5 days after linezolid treatment was stopped.

DISCUSSION:

The symptoms observed in our patients were consistent with Sternbach's criteria for ST. A review of published case reports showed a short time to onset of symptoms following the introduction of linezolid, generally within 1–3 days. Also of note is the use of relatively high dosages of serotonergic drugs. Use of the Naranjo probability scale indicated a possible relationship between the use of linezolid and the occurrence of ST in both cases.

CONCLUSIONS:

Clinicians should pay special attention to patients treated with serotonergic drugs, especially those receiving dosages in the higher end of the normal range who are prescribed linezolid, and consider tapering or reducing the dosage of serotonergic drugs for the duration of antibiotic therapy.

Pain reactivity in 2-month-old infants after prenatal and postnatal serotonin reuptake inhibitor medication exposure

OBJECTIVE

In this prospective study, we examined biobehavioral responses to acute procedural pain at 2 months of age in infants with prenatal and postnatal selective serotonin reuptake inhibitor (SSRI) medication exposure. Based on previous findings showing reduced pain responses in newborns after prenatal exposure, we hypothesized that altered pain reactivity would also be found at 2 months of age.

METHODS

Facial action (Neonatal Facial Coding System) and cardiac autonomic reactivity derived from the respiratory activity and heart rate variability (HRV) responses to a painful event (heel-lance) were compared between 3 groups of infants: (1) infants with prenatal SSRI exposure alone (n = 11; fluoxetine, n = 2; paroxetine, n = 9); (2) infants with prenatal and postnatal SSRI (via breast milk) exposure (total n = 30; fluoxetine, n = 6; paroxetine, n = 20; sertraline, n = 4); and (3) control infants (n = 22; nonexposed) during baseline, lance, and recovery periods. Measures of maternal mood and drug levels were also obtained, and Bayley Scales of Infant Development-II were administered at ages 2 and 8 months.

RESULTS

Facial action increased in all groups immediately after the lance but was significantly lower in the pSE group during the lance period. HR among infants in the pSE and ppSE groups was significantly lower during recovery. Using measures of HRV and the transfer relationship between heart rate and respiration, exposed infants had a greater return of parasympathetic cardiac modulation in the recovery period, whereas a sustained sympathetic response continued in control infants. Although postnatal exposure via breast milk was extremely low when infant drug levels could be detected in ppSE infants, changes in HR and HRV from lance to recovery were greater compared among infants with levels too low to be quantified. Neither maternal mood nor the presence of clonazepam influenced pain responses.

CONCLUSIONS

Blunted facial-action responses were observed among infants with prenatal SSRI exposure alone, whereas both prenatal and postnatal exposure was associated with reduced parasympathetic withdrawal and increased parasympathetic cardiac modulation during recovery after an acute noxious event. These findings are consistent with patterns of pain reactivity observed in the newborn period in the same cohort. Given that postnatal exposure via breast milk was extremely low and altered biobehavioral pain reactivity was not associated with levels of maternal reports of depression, these data suggest possible sustained neurobehavioral outcomes beyond the newborn period. This is the first study of pain reactivity in infants with prenatal and postnatal SSRI exposure, and our findings were limited by the lack of a depressed nonmedicated control group, small sample size, and understanding of infant behaviors associated with pain reactivity that could have also have been influenced by prenatal SSRI exposure. The developmental and clinical implications of our findings remain unclear, and the mechanisms that may have altered 5-hydroxytryptamine-mediated pain modulation in infants after SSRI exposure remain to be studied. Treating maternal depression with antidepressants during and after pregnancy and promoting breastfeeding in this setting should remain a key goal for all clinicians. Additional study is needed to understand the long-term effects of prenatal and early postnatal SSRI exposure.