Dyskinesias associated with atomoxetine in combination with other psychoactive drugs

Serotonin syndrome induced by overdose of atomoxetine alone in a patient with attention-deficit hyperactivity disorder: A case report

Background

Serotonin syndrome is characterized by mental status changes, autonomic hyperactivity, and neuromuscular abnormalities. This syndrome results from various medications that engender serotonergic overactivity. Atomoxetine is a norepinephrine reuptake inhibitor used for the treatment of attention-deficit hyperactivity disorder (ADHD). Two case reports have described serotonin syndrome induced by the combination of atomoxetine with venlafaxine or methylphenidate, but no report describes this syndrome induced by atomoxetine alone. This report describes serotonin syndrome induced solely by an overdose of atomoxetine in a patient with ADHD.

Case Presentation

The patient in this case was a 21-year-old man who had been treated with atomoxetine for ADHD. He was transported to our hospital 1 h after intentional ingestion of 1200 mg of atomoxetine in a suicide attempt. On admission, he showed profuse diaphoresis, marked agitation, somnolence, slight fever, tachycardia, prolonged QT interval, myoclonus, tremor, and hyperreflexia. He was diagnosed as having serotonin syndrome and was treated with administration of activated charcoal and massive infusion. Three days later, his serotonin syndrome symptoms had disappeared completely.

Conclusion

Findings in this case suggest that atomoxetine alone can cause serotonin syndrome presumably via its effects of serotonin reuptake inhibition. Clinicians should consider this syndrome induced by atomoxetine overdose.

Tardive Dyskinesia-like Syndrome Due to Drugs that do not Block Dopamine Receptors: Rare or Non-existent: Literature Review

Background

Although tardive dyskinesia (TD) is most commonly defined as a movement disorder caused by chronic exposure to dopamine‐receptor‐blocking drugs (DRBDs), it has also been thought to result from exposure to some non‐DRBDs.

Methods

We critiqued many reviews making the association between non‐DRBDs and a TD‐like syndrome and almost all case reports. We checked whether cases met criteria for the diagnosis of TD‐like syndrome and whether DRBDs had been excluded.

Results

We found that both tricyclic antidepressants and selective serotonin reuptake inhibitor antidepressants may unmask or exacerbate TD after prior exposure to or with concurrent use of DRBDs. We found support for its existence outside of this context to be extremely weak.

Discussion

There is little evidence that drugs other than DRBDs by themselves cause a TD syndrome; most reported cases appear to occur as a result of a “priming” effect induced by a DRBD, which is later unmasked.

Extrapyramidal Reactions Associated with Serotonergic Antidepressants

OBJECTIVE

Extrapyramidal reactions (EPRs) associated with serotonergic antidepressant treatments have been reported since 1958. These reactions can be distressing for patients and complicate treatment. Our objective was to complete a follow-up review of published EPR cases reported for serotonergic antidepressants.

DATA SOURCES

Published cases between January 1998 and May 2015 were collected through a medical literature search. Citation reference lists were also searched manually.

STUDY SELECTION AND DATA EXTRACTION

Identified cases were reviewed for patient age, gender, psychiatric diagnosis, dosage, time to reaction onset, concurrent medications, and EPR description. Cases were excluded when there was not a clear description, if descriptions were not consistent with accepted definitions, or if the written English was poor. We included cases of akathisia, dystonia, dyskinesia, parkinsonism, or mixed EPRs. Authors scored each case using the Naranjo adverse drug reaction probability scale.

DATA SYNTHESIS

We identified 86 published reports involving 91 patients; selective serotonin reuptake inhibitors were implicated in 80.2% of cases. All EPR types were reported: 17 akathisia cases, 18 dyskinesia cases, 27 dystonia cases, 19 parkinsonism cases, and 10 mixed EPR cases. EPRs typically occurred within 30 days of either treatment initiation or dose increase. Age, gender, antidepressant dosing, or concurrent antipsychotic treatment did not appear to broadly contribute to EPR risk. Naranjo scores ranged from 2 to 8.

CONCLUSIONS

Case reports associating serotonergic antidepressants with EPRs continue to be published. Practitioners are advised that monitoring for such is important. Rigorous research efforts are needed to better understand the clinical risk factors for these adverse drug reactions.

Overdose of drugs for attention-deficit hyperactivity disorder: clinical presentation, mechanisms of toxicity, and management

The prevalence of attention-deficit hyperactivity disorder (ADHD) in the USA is estimated at approximately 4-9% in children and 4% in adults. It is estimated that prescriptions for ADHD medications are written for more than 2.7 million children per year. In 2010, US poison centers reported 17,000 human exposures to ADHD medications, with 80% occurring in children <19 years old and 20% in adults. The drugs used for the treatment of ADHD are diverse but can be roughly separated into two groups: the stimulants such as amphetamine, methylphenidate, and modafinil; and the non-stimulants such as atomoxetine, guanfacine, and clonidine. This review focuses on mechanisms of toxicity after overdose with ADHD medications, clinical effects from overdose, and management. Amphetamine, dextroamphetamine, and methylphenidate act as substrates for the cellular monoamine transporter, especially the dopamine transporter (DAT) and less so the norepinephrine (NET) and serotonin transporter. The mechanism of toxicity is primarily related to excessive extracellular dopamine, norepinephrine, and serotonin. The primary clinical syndrome involves prominent neurological and cardiovascular effects, but secondary complications can involve renal, muscle, pulmonary, and gastrointestinal (GI) effects. In overdose, the patient may present with mydriasis, tremor, agitation, hyperreflexia, combative behavior, confusion, hallucinations, delirium, anxiety, paranoia, movement disorders, and seizures. The management of amphetamine, dextroamphetamine, and methylphenidate overdose is largely supportive, with a focus on interruption of the sympathomimetic syndrome with judicious use of benzodiazepines. In cases where agitation, delirium, and movement disorders are unresponsive to benzodiazepines, second-line therapies include antipsychotics such as ziprasidone or haloperidol, central alpha-adrenoreceptor agonists such as dexmedetomidine, or propofol. Modafinil is not US FDA approved for treatment of ADHD; however, it has been shown to improve ADHD signs and symptoms and has been used as an off-label pharmaceutical for this diagnosis in both adults and children. The mechanism of action of modafinil is complex and not fully understood. It is known to cause an increase in extracellular concentrations of dopamine, norepinephrine, and serotonin in the neocortex. Overdose with modafinil is generally of moderate severity, with reported ingestions of doses up to 8 g. The most common neurological effects include increased anxiety, agitation, headache, dizziness, insomnia, tremors, and dystonia. The management of modafinil overdose is largely supportive, with a focus on sedation, and control of dyskinesias and blood pressure. Atomoxetine is a selective presynaptic norepinephrine transporter inhibitor. The clinical presentation after overdose with atomoxetine has generally been mild. The primary effects have been drowsiness, agitation, hyperactivity, GI upset, tremor, hyperreflexia, tachycardia hypertension, and seizure. The management of atomoxetine overdose is largely supportive, with a focus on sedation, and control of dyskinesias and seizures. Clonidine is a synthetic imidazole derivative with both central and peripheral alpha-adrenergic agonist actions. The primary clinical syndrome involves prominent neurological and cardiovascular effects, with the most commonly reported features of depressed sensorium, bradycardia, and hypotension. While clonidine is an anti-hypertensive medication, a paradoxical hypertension may occur early with overdose. The clinical syndrome after overdose of guanfacine may be mixed depending on central or peripheral alpha-adrenoreceptor effects. Initial clinical effects may be drowsiness, lethargy, dry mouth, and diaphoresis. Cardiovascular effects may depend on time post-ingestion and may present as hypotension or hypertension. The management of guanfacine overdose is largely supportive, with a focus on support of blood pressure. Overdose with ADHD medications can produce major morbidity, with many cases requiring intensive care medicine and prolonged hospital stays. However, fatalities are rare with appropriate care.

A systematic review of combination therapy with stimulants and atomoxetine for attention-deficit/hyperactivity disorder, including patient characteristics, treatment strategies, effectiveness, and tolerability

OBJECTIVE

The purpose of this article was to systematically review the literature on stimulant and atomoxetine combination therapy, in particular: 1) Characteristics of patients with attention-deficit/hyperactivity disorder (ADHD) given combination therapy, 2) treatment strategies used, 3) efficacy and effectiveness, and 4) safety and tolerability.

METHODS

Literature databases (MEDLINE(®), EMBASE, Cochrane Central Register of Controlled Trials, Science Citation Index Expanded, and SciVerse Scopus) were systematically searched using prespecified criteria. Publications describing stimulant and atomoxetine combination therapy in patients with ADHD or healthy volunteers were selected for review. Exclusion criteria were comorbid psychosis, bipolar disorder, epilepsy, or other psychiatric/neurologic diseases that could confound ADHD symptom assessment, or other concomitant medication(s) to treat ADHD symptoms.

RESULTS

Of the 16 publications included for review, 14 reported findings from 3 prospective studies (4 publications), 7 retrospective studies, and 3 narrative reviews/medication algorithms of patients with ADHD. The other two publications reported findings from two prospective studies of healthy volunteers. The main reason for prescribing combination therapy was inadequate response to previous treatment. In the studies of patients with ADHD, if reported, 1) most patients were children/adolescents and male, and had a combined ADHD subtype; 2) methylphenidate was most often used in combination with atomoxetine for treatment augmentation or switch; 3) ADHD symptom control was improved in some, but not all, patients; and 4) there were no serious adverse events.

CONCLUSIONS

Published evidence of the off-label use of stimulant and atomoxetine combination therapy is limited because of the small number of publications, heterogeneous study designs (there was only one prospective, randomized controlled trial), small sample sizes, and geographic bias. Existing evidence suggests, but does not confirm, that this drug combination may benefit some, but not all, patients who have tried several ADHD medications without success.

Cases of adverse reaction to psychotropic drugs and possible association with pharmacogenetics

Thousands of samples for pharmacogenetic tests have been analysed in our laboratory since its establishment. In this article we describe some of the most interesting cases of CYP poor metabolisers associated with adverse reactions to psychotropic drugs. Prevention of disease/illness, including Adverse Drug Reaction (ADR), is an aim of modern medicine. Scientific data supports the fact that evaluation of drug toxicology includes several factors, one of which is genetic variations in pharmacodynamics and pharmacokinetics of drug pathways. These variations are only a part of toxicity evaluation, however, even if it would help to prevent only a small percentage of patients from suffering adverse drug reactions, especially life threatening ADRs, pharmacogenetic testing should play a significant role in any modern psychopharmacologic practice. Medical practitioners should also consider the use of other medications or alternative dosing strategies for drugs in patients identified as altered metabolisers. This will promise not only better and safer treatments for patients, but also potentially lowering overall healthcare costs.

Efficacy and Safety of Atomoxetine in the Treatment of Children and Adolescents with Attention Deficit Hyperactivity Disorder

Several non-stimulant medications have been used in the treatment of attention deficit hyperactivity disorder (ADHD). Atomoxetine, was introduced in 2002. The safety and efficacy of atomoxetine in the treatment of ADHD for children, adolescents, and adults has been evaluated in over 4000 patients in randomized controlled studies and double blinded studies as well as in recent large longitudinal studies. This paper provides an updated summary of the literature on atomoxetine, particularly in relation to findings on the short- and long-term safety of atomoxetine in children and adolescents arising from recent large longitudinal cohort studies. Information is presented about the efficacy, safety, and tolerability of this medication.

Suicide cases and venlafaxine

Piatkov I, Jones T, Van Vuuren RJ. Suicide cases and venlafaxine.

Objective: Our aim was to establish whether the presence or absence of fully functioning cytochrome P450 2D6, 2C19 and 2C9 genetic alleles was associated with suicide in patients receiving venlafaxine treatment.

Method: Authorisation from the NSW State Coroner to perform post-mortem genetic testing was obtained for 11 samples from deceased persons who committed suicide during treatment with venlafaxine (VENADR study).

Results: All patients, but one, have at least one copy of the loss-of-function, altered or decreased cytochrome P450 enzyme activity allele. Four patients' results reveal loss-of-function genotypes, while all others were found to have diminished enzyme activity polymorphisms. Seven patients had multiple altered function polymorphisms, which included CYP2D6, CYP2C19 or CYP2C9.

Conclusion: Our preliminary limited data show that neurotoxicity development, which manifests as suicide while on venlafaxine treatment, probably correlates with a higher prevalence of gene copies of altered functioning cytochrome P450 genetic polymorphisms.

Atomoxetine for the treatment of attention-deficit/hyperactivity disorder in children and adolescents: a review

OBJECTIVE

This review examines and summarizes the pharmacodynamic and pharmacokinetic properties, short- and longer-term efficacy, the moderating effect of comorbid disorders, as well as short- and long-term safety and tolerability of atomoxetine for the treatment of pediatric attention-deficit/hyperactivity disorder (ADHD).

METHODS

A systematic literature search was performed to review the extant literature on articles pertaining to the pharmacological treatment with atomoxetine in pediatric and/or adolescent ADHD.

RESULTS

There is an extensive literature on atomoxetine; over 4000 children have participated in clinical trials of atomoxetine, demonstrating its short- and longer-term efficacy. In addition, studies have examined the moderating effect of comorbid disorders on atomoxetine response, as well as atomoxetine's therapeutic potential for other psychiatric conditions. Short- and longer-term safety and tolerability continue to be reported.

CONCLUSIONS

Atomoxetine is indicated for both acute and maintenance/extended treatment of pediatric ADHD. Clinicians and families must be familiar with atomoxetine's evidence base, including its profile of clinical response and its possible effectiveness in the presence of comorbidity.