Case files of the program in medical toxicology at brown university: amantadine withdrawal and the neuroleptic malignant syndrome

Amantadine withdrawal in a patient with spinocerebellar ataxia

We report a case of a man with spinocerebellar ataxia (SCA) on high-dose amantadine who was admitted for acute on chronic dysphagia secondary to progression of SCA. Four days after oral medications were held due to patient's dysphagia, he developed fever, tachycardia and mild rigidity in extremities and became obtunded. Despite antibiotics treatment, the vitals and mental status changes persisted for 8 days. When amantadine was resumed, the patient's vital signs and encephalopathy improved within 2 days. This is among the first reports of amantadine withdrawal syndrome (AWS) in a patient without Parkinson's disease. Our case reinforces the importance of careful medication review at admission and consideration of pharmacologic side effects with not only medication initiation but also discontinuation.

Rapid symptom control in neuroleptic malignant syndrome with electroconvulsive therapy: A case report

Introduction

Neuroleptic malignant syndrome (NMS), thought to arise through dopamine antagonism, is life-threatening. While prompt diagnosis of NMS is critical, it may be obscured by other diagnoses, such as malignant catatonia, with overlapping, life-threatening symptoms. Initiation of dopamine-blocking agents such as antipsychotics and abrupt cessation of dopaminergic medications such as amantadine can precipitate NMS. Once NMS is suspected, deft medical management should ensue. Multiple case reports detail electroconvulsive therapy's (ECT's) effectiveness in the treatment of NMS. While this relationship is well-documented, there is less literature regarding comparative efficacy of ECT in the acute treatment of NMS-like states precipitated by withdrawal of dopamine agonists, such as amantadine.

Case

We present a 52-year-old female with schizoaffective disorder bipolar type, with a history of a lorazepam-resistant catatonic episode the prior year that had responded to amantadine. She presented febrile with altered mental status, lead pipe rigidity, mutism, grasp reflex, stereotypy, autonomic instability, and a Bush-Francis Catatonia Rating Scale (BFCRS) of 24, suggesting malignant catatonia versus NMS. There was concern over a potentially abrupt cessation of her amantadine of which she had been prescribed for the past year.

Interventions

Organic etiologies were ruled out, and a presumptive diagnosis of NMS was made with central dopaminergic depletion from abrupt dopamine agonist (amantadine) withdrawal as the suspected underlying etiology. After intravenous lorazepam and reinduction of amantadine failed to alleviate her symptoms, urgent ECT was initiated. Our patient received an index series of ECT of seven treatments. After ECT #1 she was no longer obtunded, after treatment #2 her symptoms of mutism, rigidity, stereotypy, and agitation showed improvement, and by ECT #3, the NMS had rapidly dissipated as evidenced by stable vital signs, lack of rigidity, and coherent conversation.

Conclusion

Brisk identification of potentially life-threatening NMS and NMS-like states, including malignant catatonia, warrants a trial of ECT. ECT's theoretical mechanisms of action coincide with the theoretical pathophysiology of the conditions. It is a viable and safe treatment option for reducing mortality. With prompt initiation of ECT, we obtained rapid control of a condition with a potentially high mortality.

Implications of dopaminergic medication withdrawal in Parkinson's disease

The trajectory of the use of dopamine replacement therapy (DRT) in Parkinson's disease (PD) is variable and doses may need to be increased, but also tapered. The plan for dose adjustment is usually done as per drug information recommendations from the licensing bodies, but there are no clear guidelines with regards to the best practice regarding the tapering off schedule given sudden dose reductions of drugs such as dopamine agonists may have serious adverse consequences. A systematic literature search was, therefore, performed to derive recommendations and the data show that there are no controlled studies or evidence-based recommendations how to taper or discontinue PD medication in a systematic manner. Most of the data were available on the dopamine agonist withdrawal syndrome (DAWS) and we found only two instructions on how to reduce pramipexole and rotigotine published by the EMA. We suggest that based on the available data, levodopa, dopamine agonists (DA), and amantadine should not be discontinued abruptly. Abrupt or sudden reduction of DA or amantadine in particular can lead to severe life-threatening withdrawal symptoms. Tapering off levodopa, COMT inhibitors, and MAO-B inhibitors may worsen motor and non-motor symptoms. Based on our clinical experience, we have proposed how to reduce PD medication and this work will form the basis of a future Delphi panel to define the recommendations in a consensus.

Parkinsonism-hyperpyrexia Syndrome After Amantadine Withdrawal: Case Report and Review of the Literature

INTRODUCTION

Parkinsonism-hyperpyrexia syndrome (PHS) is a rare and potentially fatal complication of Parkinson disease (PD) characterized by a neuroleptic malignant-like syndrome due to abrupt discontinuation of antiparkinsonian medications.

CASE REPORT

A 79-year-old woman with late-stage PD presented at the hospital with neuropsychiatric and uncontrolled parkinsonian motor symptoms. Soon after the abrupt discontinuation of amantadine, the patient suddenly presented with global rigidity, global unresponsiveness, diaphoresis, tachycardia, recurrent hyperpyrexia, and a mildly elevated creatine kinase, which lead to the diagnosis of PHS. Amantadine was then reinitiated and her symptoms resolved within 10 days.

CONCLUSIONS

Amantadine is an antiparkinsonian medication scarcely associated with PHS. The few reported cases are further summarized and discussed in this article. This case highlights the importance of early recognition of PHS, which may be caused by changes in other antiparkinson agents such as amantadine, and the need to slowly titrate such agents.

Amantadine withdrawal syndrome masquerading as COVID-19 encephalopathy: a case report and review of the literature

Amantadine withdrawal syndrome (AWS) is a rare but recognized cause of severe and persistent altered mental status sometimes with co-occurring extrapyramidal symptoms. First described in a case series from 1987, its clinical manifestations have been characterized along a spectrum ranging from profound hypoactive delirium to hyperactive delirium with hallucinations. Risk factors for withdrawal include abrupt medication discontinuation, prolonged use, older age and underlying dementia.

Herein we describe a case of a 52-year-old woman who presented with confusion, hallucinations, and coronavirus disease-2019 infection. She subsequently developed a prolonged hypoactive delirium after her amantadine was tapered and held. Her hypoactive delirium entirely resolved with resumption of amantadine confirming the diagnosis of AWS. This case illustrates the importance of slowly tapering dopaminergic medications and being aware of rare pharmacologic side effects.

Dependence, withdrawal and rebound of CNS drugs: an update and regulatory considerations for new drugs development

The purpose of this article is to describe dependence and withdrawal phenomena related to CNS drugs discontinuation and to clarify issues related to the evaluation of clinical drug withdrawal and rebound as they relate to safety in new drug development. The article presents current understanding and definitions of drug dependence and withdrawal which are also relevant and important features of addiction, though not the same. Addiction, called substance use disorder in DSM-5, affects an individual’s brain and behaviour, represents uncontrollable drug abuse and inability to stop taking a drug regardless of the harm it causes. Characteristic withdrawal syndromes following abrupt discontinuation of CNS-active drugs from numerous drug classes are described. These include drugs both scheduled and non-scheduled in the Controlled Substances Act, which categorizes drugs in five schedules based on their relative abuse potentials and dependence liabilities and for regulatory purposes. Schedules 1 and 2 contain drugs identified as those with the highest abuse potential and strictest regulations. Less recognized aspects of drug withdrawal, such as rebound and protracted withdrawal syndromes for several drug classes are also addressed. Part I presents relevant definitions and describes clinical withdrawal and dependence phenomena. Part II reviews known withdrawal syndromes for the different drug classes, Part III describes rebound and Part IV describes protracted withdrawal syndromes. To our knowledge, this is the first compilation of withdrawal syndromes for CNS drugs. Part V provides details of evaluation of dependence and withdrawal in the clinical trials for CNS drugs, which includes general design recommendations, and several tools, such as withdrawal questionnaires and multiple scales that are helpful in the systematic evaluation of withdrawal. The limitations of different aspects of this method of dependence and withdrawal evaluation are also discussed.

Neuroleptic malignant syndrome and serotonin syndrome

The clinical manifestation of drug-induced abnormalities in thermoregulation occurs across a variety of drug mechanisms. The aim of this chapter is to review two of the most common drug-induced hyperthermic states, serotonin syndrome and neuroleptic malignant syndrome. Clinical features, pathophysiology, and treatment strategies will be discussed, in addition to differentiating between these two syndromes and differentiating them from other hyperthermic or febrile syndromes. Our goal is to both review the current literature and to provide a practical guide to identification and treatment of these potentially life-threatening illnesses. The diagnostic and treatment recommendations made by us, and by other authors, are likely to change with a better understanding of the pathophysiology of these syndromes.

The Role of Amantadine Withdrawal in 3 Cases of Treatment-Refractory Altered Mental Status

Amantadine, which was originally developed as an antiviral medication, functions as a dopamine agonist in the central nervous system and consequently is utilized in the treatment of Parkinson disease, drug-induced extrapyramidal reactions, and neuroleptic malignant syndrome. For reasons that are not entirely understood, abrupt changes in amantadine dosage can produce a severe withdrawal syndrome. Existing medical literature describes case reports of amantadine withdrawal leading to delirium, which at times has progressed to neuroleptic malignant syndrome. Amantadine withdrawal may be under-recognized by mental health clinicians, which has the potential to lead to protracted hospital courses and suboptimal outcomes. The goal of this case series is to highlight the role of amantadine withdrawal in the cases of 3 medically complex patients with altered mental status. In the first case, the cognitive side effects of electroconvulsive therapy masked acute amantadine withdrawal in a 64-year-old man with Parkinson disease. In the second case, a 75-year-old depressed patient developed a catatonic delirium when amantadine was discontinued. Finally, a refractory case of neuroleptic malignant syndrome in a 57-year-old patient with schizoaffective disorder rapidly resolved with the reintroduction of outpatient amantadine. These cases highlight several learning objectives regarding amantadine withdrawal syndrome: First, it may be concealed by co-occurring causes of delirium in medically complex patients. Second, its symptoms are likely to be related to a cortical and limbic dopamine shortage, which may be reversed with electroconvulsive therapy or reintroduction of amantadine. Third, its clinical presentation may occur on a spectrum and may include features suggestive of delirium, catatonia, or neuroleptic malignant syndrome.

Neuroleptic Malignant Syndrome

Objective: To review evidence for the treatment of neuroleptic malignant syndrome (NMS) and to discuss how to rechallenge patients with neuroleptics when continued pharmacotherapy for chronic psychological illness is required. Data Sources: A PubMed search was conducted through March 2016 using available medical subject heading (MeSH) terms and keywords that included neuroleptic malignant syndrome, treatment, dantrolene, and bromocriptine. A manual search of article reference sections followed. Study Selection and Data Extraction: Case reports and case series in English that discussed NMS and atypical NMS treatment as well as neuroleptic rechallenge were included for review. Data Synthesis: The reported incidence of NMS was 0.02% to 0.03%, with a mortality rate of 5.6%. Current literature on NMS is primarily retrospective and emphasizes diagnostic criteria, causative agents, and potential pharmacotherapy. Details regarding timing of administration, dose, and duration of pharmacotherapy are inconsistently reported. Reported dosing strategies and outcomes have been summarized. Instances of rechallenge were infrequently reported but demonstrate that recurrence may happen at any time after NMS resolution. Recommendations regarding safe rechallenge are provided. Conclusion: NMS is a rare adverse drug reaction, with a complex pathophysiology and presentation. Timely diagnosis and discontinuation of antipsychotic therapy is the first-line treatment, followed by supportive care and pharmacotherapy. Antipsychotic rechallenge is often required and should be attempted only after a drug-free period and with a different agent, slowly titrated with close monitoring.