Effect of anticholinergics in preventing acute deterioration in patients undergoing abrupt clozapine withdrawal

Letter to the FDA Proposing Major Changes in the US Clozapine Package Insert Supported by Clozapine Experts Worldwide. Part I: A Review of the Pharmacokinetic Literature and Proposed Changes

PURPOSE/BACKGROUND

Clozapine was approved in the United States (US) using 1989 regulations and knowledge. After 30 years, many sections of the US package insert (PI) are outdated.

METHODS

We comprehensively reviewed the literature to propose PI updates. We present the information in 2 articles. In Part I, we focus on basic pharmacology based on 407 relevant articles. Part II focuses on clinical aspects and pharmacovigilance.

FINDINGS/RESULTS

Based on more recent expectations of Food and Drug Administration regulations, we reviewed clozapine basic pharmacology including the following: 1) clearance, 2) pharmacokinetics and pharmacodynamics, and 3) monitoring tools. We identified 9 major problems in the basic pharmacological sections of the PI including the following: 1) in vivo studies indicate that clozapine is dependent on CYP1A2 for its metabolism, 2) the minor role of CYP2D6 in clozapine metabolism requires removing the PI recommendation to lower clozapine doses in CYP2D6 poor metabolizers, 3) in nontoxic concentrations CYP3A4 has a minor role in clozapine metabolism and potent CYP3A4 inhibitors lack clinically relevant effects, 4) several drug-drug interactions need to be updated based on recent literature, 5) systemic inflammation may decrease clozapine metabolism and increase the risk of clozapine intoxication, 6) obesity may decrease clozapine metabolism, 7) patients of Asian and Indigenous American ancestry need lower clozapine doses, 8) personalized titration and c-reactive protein monitoring should be considered until prospective studies are available, and 9) the half-life section needs to be modified to acknowledge that single dosing at night is frequent in the US.

IMPLICATIONS/CONCLUSIONS

An improvement in the US clozapine PI may lead to improvement in PIs worldwide.

Management of Cholinergic Rebound After Abrupt Withdrawal of Clozapine: A Case Report and Systematic Literature Review

BACKGROUND

Cholinergic discontinuation symptoms, also known as "cholinergic rebound," from abrupt clozapine discontinuation are characterized by a range of somatic and psychiatric symptoms.

OBJECTIVE

The objective of this study was to describe the clinical features and management options for clozapine withdrawal-associated cholinergic rebound syndrome (henceforth referred to as CWCRS) and present an illustrative case report.

METHODS

Based on a literature search of the databases PubMed, OVID Medline, and Embase as well as reviewing reference lists of relevant past reviews, we carried out a systematic review of case reports on the management of CWCRS from 1946 to 2023.

RESULTS

We identified 10 previously published articles on the clinical management of CWCRS, with a total of 18 patients (6 female, 12 male) with an average age of 43 years (standard deviation 14). Half of the patients had a history of tardive dyskinesia. The mean dose of clozapine before discontinuation was 351 mg/day, with duration of clozapine treatment ranging from 3 weeks to 9 years. Clozapine was the most effective treatment, followed by benztropine.

CONCLUSIONS

Given the small number of cases and the nonexperimental nature of the available studies, this review could not provide reliable data to guide management of CWCRS. The findings, however, suggest that clozapine may be more effective than other commonly used treatment options. With the high rates of discontinuation among patients on clozapine, there is a pressing need for further research into the epidemiology, natural history, and management of clozapine withdrawal syndromes.

Clozapine Withdrawal Catatonia: A Case Report

Catatonia, which is associated with gamma-aminobutyric acid (GABA) hypoactivity, often responds robustly to benzodiazepines. It has been reported to be a consequence of abrupt discontinuation of clozapine, an antipsychotic used for treatment-resistant schizophrenia. Clozapine discontinuation, sometimes necessitated by medical concerns, can carry the risk of adverse outcomes, including catatonia. We present the case of a 66-year-old African-American male with schizoaffective disorder (depressive subtype) and a complex medical history. He discontinued clozapine abruptly due to medication unavailability, and, seven days later, presented with catatonic symptoms, initially unrecognized by emergency room clinicians. His symptoms included self-neglect, auditory hallucinations, isolation, psychomotor retardation, fixed gaze, and thought blocking. An attempt to reinstate clozapine led to orthostatic hypotension, prompting admission to an inpatient psychiatry unit. Attempt to initiate risperidone for psychosis worsened the catatonia, which then responded rapidly to intravenous lorazepam challenge. This facilitated the re-introduction of clozapine with slow re-titration.

[Safety aspects during treatment with clozapine. : Monitoring and rechallenge - a narrative review]

BACKGROUND

Due to its unique efficacy in treatment-resistant schizophrenia, discontinuation of treatment with clozapine is frequently associated with a significant worsening of symptoms, but also with an increased risk of suicide. Based on the literature, this review aims at summarizing different monitoring recommendations in order to be able to continue this therapy despite the occurrence of side effects. In addition, we provide recommendations when rechallenge of a previously stopped treatment with clozapine can be considered and when a definite discontinuation must take place.

MATERIAL AND METHODS

Medline, the Guideline for the use of clozapine 2013 of the Netherlands Clozapine Collaboration Group, and the S3 Guideline for Schizophrenia of the German Association of Psychiatry, Psychotherapy and Psychosomatics were searched for relevant literature, the last query dating from April 28th, 2023.

RESULTS

If agranulocytosis or cardiomyopathy develops, treatment with clozapine must be discontinued and should not be resumed thereafter. In contrast, treatment with clozapine which had to be discontinued due to myocarditis or prolongation of the QTc interval may be continued if left ventricular function is normal or after normalization of the QTc interval. Other side effects are usually not absolute contraindications for rechallenge but often require the adjunctive use of additional pharmacologic and non-pharmacologic measures.

CONCLUSION

Taking into consideration various monitoring recommendations, cessation of treatment with clozapine can often be prevented or treatment with clozapine that has been discontinued due to side effects can be resumed.

Recognition and Treatment Challenges of Acute Clozapine Withdrawal Syndrome: A Case Report

The limited psychiatric bedspace due to the COVID-19 pandemic and the lack of access to an up-to-date medication regimen delayed the recognition of the diagnosis and treatment for a 40-year-old man with schizoaffective disorder, bipolar type, who traveled from his home city and abruptly discontinued his prescription of clozapine. He developed a cholinergic rebound syndrome including delirium and extrapyramidal symptoms (EPS). The delay included time spent in two different medical hospitals: one awaiting psychiatric bedspace, and secondly, when the patient's cholinergic rebound syndrome was misdiagnosed as acute alcohol withdrawal. Once the etiology was recognized, he was promptly treated with anticholinergic medication (benztropine) and retitrated to his outpatient dose of clozapine leading to the resolution of symptoms including delirium and EPS. This case will discuss the challenges of continuity of care in delirious, psychotic, or otherwise confused patients, including contributions from the COVID-19 pandemic. A medication card or other improvements in medication databases that may reduce delays in treatment are discussed.

Clinical Outcomes after Clozapine Discontinuation in Patients with Schizophrenia: A Systematic Review

INTRODUCTION

Clozapine is the gold standard of treatment for patients with treatment-resistant schizophrenia. However, approximately 60% of those patients do not respond to clozapine; moreover, clinical outcomes after clozapine discontinuation are unclear so far. Therefore, we conducted a systematic review to clarify the outcomes after clozapine discontinuation.

METHODS

A systematic literature search was conducted, using MEDLINE and Embase with the following keywords: (clozapine AND (cessation* OR cease* OR withdraw* OR discontinu* OR halt* OR stop* OR switch*) AND (schizophreni* OR schizoaffective)).

RESULTS

A total of 28 clinical studies from 27 articles were identified and included in this systematic review. Three randomized controlled trials reported worsening of psychiatric symptoms. In 10 single-arm studies, the results of worsening and improving psychiatric symptoms were inconsistent. In one large retrospective cohort study, clozapine rechallenge, olanzapine, and antipsychotic polypharmacy had lower rehospitalization rates compared to no medication after clozapine discontinuation. In the other 14 retrospective studies, the vast majority showed worsening of clinical status after clozapine discontinuation. Among five studies on clinical outcomes after clozapine rechallenge, four reported improvements in clinical status in more than half of patients who rechallenged clozapine. The remaining study reported that the clozapine discontinuation-rechallenge group had a worse remission assessment score than the clozapine discontinuation-no rechallenge group.

DISCUSSION

Clinical outcomes generally worsen after clozapine discontinuation. Clozapine rechallenge and olanzapine may be considered following clozapine discontinuation. The outcomes after clozapine discontinuation in clozapine non-responders remain inconclusive; therefore, well-designed studies are warranted.

Demographic and clinical characteristics of patients who recommence clozapine following therapy interruptions

OBJECTIVE

The proportion of patients who recommence clozapine after cessation, the time taken to resume clozapine post-cessation, and distinguishing demographic and clinical characteristics of this group have been poorly researched. We evaluated these in the current study.

METHOD

We retrospectively extracted selected demographic and clinical variables and clozapine treatment interruption and recommencement data up to December 2018 of a cohort of 458 patients who first commenced clozapine between 2006 and 2016. The study was conducted at three Australian health services.

RESULTS

Of the 310 (69%) patients who had at least one interruption of clozapine treatment, 170 (54.8%) did not resume clozapine, and 140 (45.2%) recommenced it after the first interruption. More than half of those who recommenced did so within a month and 80% by 12 months. Cox regression analysis revealed that age was significantly associated with recommencement, with a 2% decrease in the likelihood of restarting after an interruption for each year later that clozapine was initially commenced (HR = 0.98 95%CI: 0.97, 0.997, p = 0.02). Those who ceased clozapine due to adverse effects were less likely to restart than those who ceased due to noncompliance (HR = 0.63 95%CI: 0.41, 0.97, p = 0.03). More time on clozapine prior to interruption increased the likelihood of restarting it, with each additional month on clozapine increasing this likelihood by 1% (HR = 1.01 95%CI: 1.01, 1.02, p < 0.001).

CONCLUSION

If the distinguishing demographic and clinical characteristics of the group identified in this study are corroborated through further research, this could further validate the need to identify treatment resistance and commence clozapine early in people with schizophrenia and provide appropriate interventions to those more at risk of permanent discontinuation of clozapine.

Reducing the Risk of Withdrawal Symptoms and Relapse Following Clozapine Discontinuation-Is It Feasible to Develop Evidence-Based Guidelines?

Clozapine is the only antipsychotic that is effective in treatment-resistant schizophrenia. However, in certain clinical situations, such as the emergence of serious adverse effects, it is necessary to discontinue clozapine. Stopping clozapine treatment poses a particular challenge due to the risk of psychotic relapse, as well as the development of withdrawal symptoms. Despite these challenges for the clinician, there is currently no formal guidance on how to safely to discontinue clozapine. We assessed the feasibility of developing evidence-based recommendations for (1) minimizing the risk of withdrawal symptoms, (2) managing withdrawal phenomena, and (3) commencing alternatives treatment when clozapine is discontinued. We then evaluated the recommendations against the Appraisal of Guidelines for Research and Evaluation (AGREE) II criteria. We produced 19 recommendations. The majority of these recommendation were evidence-based, although the strength of some recommendations was limited by a reliance of studies of medium to low quality. We discuss next steps in the refinement and validation of an evidence-based guideline for stopping clozapine and identify key outstanding questions.

Clozapine discontinuation withdrawal symptoms in schizophrenia

Clozapine is an atypical antipsychotic used in treatment-resistant schizophrenia. Whilst clozapine is highly effective, there are some clinical scenarios, such as the emergence of severe side effects, that necessitate its discontinuation. There is an emerging literature suggesting that discontinuing antipsychotics, in particular clozapine, can cause an array of withdrawal symptoms. We review the evidence for the existence of clozapine-induced withdrawal symptoms, and in particular focus on withdrawal-associated psychosis, cholinergic rebound, catatonia and serotonergic discontinuation symptoms. To date, there has been surprisingly little clinical guidance on how to minimise the likeliness of withdrawal symptoms in patients who are stopped on clozapine abruptly or gradually. We discuss the key outstanding questions in this area and why there is a need for guidance on the management of withdrawal symptoms associated with clozapine discontinuation.

Closure beyond clozapine: successfully averting rebound symptoms in a patient with schizoaffective disorder and agranulocytosis

SUMMARY

'Rebound' or 'withdrawal' symptoms are frequently observed after a sudden discontinuation of clozapine. We describe a patient with treatment-resistant schizoaffective disorder who developed agranulocytosis on clozapine but was successfully switched to treatment with olanzapine with no deterioration in her condition. We put forward three possible theories which may have accounted for the lack of rebound symptoms in this patient: the pharmacological profile of olanzapine, the anticholinergic effects of hyoscine hydrobromide, and the possibility that this patient may not be treatment-resistant and so have a reduced risk of rebound psychosis due to displaying a different pathophysiology.

DECLARATION OF INTEREST

None.

Predicting Unsuccessful Clozapine Treatment After First Use in Adult Patients With Psychotic Disorders

PURPOSE/BACKGROUND

Cessation of clozapine therapy and insufficient response may result in relapse of psychotic symptoms and in clinical admissions. However, discontinuation rates are high. Identifying patients at risk for unsuccessful clozapine use might enable clinicians to direct specific attention to them.

METHODS/PROCEDURES

Routinely collected data from a large insurance company were used to develop a simple prediction model for unsuccessful clozapine treatment in psychiatric patients 1 year after clozapine was first dispensed by a community pharmacy in the Netherlands. Multivariate logistic regression analyses were performed with the Nagelkerke R statistic as a measure of the predictive value of the model.

FINDINGS/RESULTS

A total of 937 patients were dispensed clozapine for the first time by their community pharmacy between January 1, 2011, and December 31, 2015 (index date). Of these, 741 patients had started their clozapine treatment in hospital before the index date (inpatient starters); the remaining 196 patients started clozapine as outpatients on the index date (outpatient starters). In 191 patients (20.4%), clozapine treatment was unsuccessful 1 year after the index date. Unsuccessful treatment was more common among outpatient starters than among inpatient starters (32.1% vs 17.3%). Using backward selection of the variables, a model consisting of 61 variables had the best predictive value overall (Nagelkerke R = 0.301), whereas a model consisting of 52 variables had the best predictive value in outpatient starters (Nagelkerke R = 0.676).

IMPLICATIONS/CONCLUSIONS

The likelihood of unsuccessful clozapine treatment after 1 year was higher among patients who started clozapine as outpatients. Despite the use of a diversity of variables and different statistical approaches, it was not possible to make a simple prediction model for unsuccessful clozapine treatment using relatively easily accessible data.

The Porirua Protocol in the Treatment of Clozapine-Induced Gastrointestinal Hypomotility and Constipation: A Pre- and Post-Treatment Study

BACKGROUND

Clozapine, an antipsychotic used in treatment-resistant schizophrenia, causes slow gastrointestinal transit in 50-80% of patients. Clozapine-induced gastrointestinal hypomotility is both common and serious, and potential complications include severe constipation, ileus, bowel obstruction and related complications, with a higher mortality rate than clozapine-related agranulocytosis. Little evidence exists on its prevention and management.

METHOD

Using a well-validated radiopaque marker ('Metcalf') method, we compared colonic transit times (CTTs) of clozapine-treated inpatients not receiving laxatives with their transit times when receiving laxatives, with treatment prescribed according to the Porirua Protocol for clozapine-related constipation (docusate and senna augmented by macrogol 3350 in treatment-resistant cases).

RESULTS

The median age of participants was 35 years, and median clozapine dose, plasma level and duration of treatment were 575 mg/day, 506 ng/mL and 2.5 years, respectively. Overall, 14 participants (10 male) were enrolled and all completed the study. Transit times improved markedly with laxative treatment. Median colonic transit without laxatives was 110 h (95% confidence interval [CI] 76-144 h), over four times longer than normative values (p < 0.0001). Median CTT with laxatives was 62 h (95% CI 27-96 h), a 2-day reduction in average transit time (p = 0.009). The prevalence of gastrointestinal hypomotility decreased from 86% pre-treatment to 50% post-treatment (p = 0.061). Severe gastrointestinal hypomotility decreased from 64 to 21% (p = 0.031). Subjective reporting of constipation did not correlate well with objective hypomotility, and did not change significantly with treatment.

CONCLUSION

Treating clozapine-treated patients with docusate and senna augmented by macrogol appears effective in reducing CTTs in clozapine-induced constipation. Randomised controlled trials are the next step. Australian New Zealand Clinical Trial Registry ACTRN12616001405404 (registered retrospectively).

Antipsychotic-induced sensitization and tolerance: Behavioral characteristics, developmental impacts, and neurobiological mechanisms

Antipsychotic sensitization and tolerance refer to the increased and decreased drug effects due to past drug use, respectively. Both effects reflect the long-term impacts of antipsychotic treatment on the brain and result from the brain's adaptive response to the foreign property of the drug. In this review, clinical evidence of the behavioral aspect of antipsychotic sensitization and tolerance is selectively reviewed, followed by an overview of preclinical literature that examines these behavioral characteristics and the related pharmacological and nonpharmacological factors. Next, recent work on the developmental impacts of adolescent antipsychotic sensitization and tolerance is presented and recent research that delineates the neurobiological mechanisms of antipsychotic sensitization and tolerance is summarized. A theoretical framework based on "drug learning and memory" principles is proposed to account for the phenomena of antipsychotic sensitization and tolerance. It is maintained that antipsychotic sensitization and tolerance follow basic principles of learning or acquisition ("induction") and memory ("expression"). The induction and expression of both effects reflect the consequences of associative and nonassociative processing and are strongly influenced by various pharmacological, environmental, and behavioral factors. Drug-induced neuroplasticity, such as functional changes of striatal dopamine D2 and prefrontal serotonin (5-HT)2A receptors and their mediated signaling pathways, in principle, is responsible for antipsychotic sensitization and tolerance. Understanding the behavioral characteristics and neurobiological underpinnings of antipsychotic sensitization and tolerance has greatly enhanced our understanding of mechanisms of antipsychotic action, and may have important implications for future drug discovery and clinical practice.

Reasons for discontinuing clozapine: A cohort study of patients commencing treatment

BACKGROUND

Clozapine is uniquely effective in the management of treatment-resistant schizophrenia (TRS). However, a substantial proportion of patients discontinue treatment and this carries a poor prognosis.

METHODS

We investigated the risk factors, reasons and timing of clozapine discontinuation in a two-year retrospective cohort study of 316 patients with TRS receiving their first course of clozapine. Reasons for discontinuation of clozapine and duration of treatment were obtained from case notes and Cox regression was employed to test the association of baseline clinical factors with clozapine discontinuation.

RESULTS

A total of 142 (45%) patients discontinued clozapine within two years. By studying the reasons for discontinuations due to a patient decision, we found that adverse drug reactions (ADRs) accounted for over half of clozapine discontinuations. Sedation was the most common ADR cited as a reason for discontinuation and the risk of discontinuation due to ADRs was highest in the first few months of clozapine treatment. High levels of deprivation in the neighbourhood where the patient lived were associated with increased risk of clozapine discontinuation (HR=2.12, 95% CI 1.30-3.47).

CONCLUSIONS

Living in a deprived neighbourhood was strongly associated with clozapine discontinuation. Clinical management to reduce the burden of ADRs in the first few months of treatment may have a significant impact and help more patients experience the benefits of clozapine treatment.

Schizophrenia past clozapine: what works?

Clozapine is superior to other antipsychotic drugs for treatment of refractory schizophrenia. However, its use has been limited by its potentially serious adverse effects. There is little guidance on the management of patients who discontinue clozapine for reasons such as lack of response, intolerance, or noncompliance. The literature was searched for studies on the efficacy of antipsychotics that replaced clozapine in such patients. The search revealed 15 papers, which were evaluated in this article. Olanzapine was the most tested alternative to clozapine with most of the studies reporting positive outcome, especially in patients with less severe illness and those who stop clozapine for reasons other than poor response. Other antipsychotics were not adequately tested in this manner. We concluded that in patients who discontinue clozapine, considering a trial of olanzapine would be worthwhile.

Environmental and behavioral controls of the expression of clozapine tolerance: evidence from a novel across-model transfer paradigm

Repeated administration of antipsychotic drugs induces a sensitization-like or tolerance-like effect in many behavioral tasks, including the conditioned avoidance response (CAR) and the phencyclidine (PCP)-induced hyperlocomotion, two rodent models with high predictive validity for antipsychotic activity. This study investigated the impacts of contextual and behavioral variables on the expression of clozapine tolerance using a recently validated across-model transfer paradigm (Zhang and Li, 2012 [1]). Male Sprague-Dawley rats were first repeatedly treated with clozapine (2.5-10.0 mg/kg, sc) in the CAR model or PCP (1.6 mg/kg, sc)-induced hyperlocomotion model for five consecutive days. They were then tested for the expression of clozapine tolerance in another model for another 5 days. Finally, all rats were switched back to the original model and tested again for the expression of clozapine tolerance. When tested in the PCP model, rats previously treated with clozapine in the CAR model did not show an immediate weaker inhibition of PCP-induced hyperlocomotion than those treated with clozapine for the first time, but showed a significantly weaker inhibition over time. In contrast, when tested in the CAR model, rats previously treated with clozapine in the PCP model showed an immediate weaker disruption of avoidance response than those treated with clozapine for the first time, but this weaker effect diminished over time. These results suggest that the expression of clozapine tolerance is strongly modulated by the test environment and/or selected behavioral response. Clozapine tolerance and its situational specificity may be related to the drug's low extrapyramidal motor side effect, its superior therapeutic efficacy and/or emergence of clozapine withdrawal syndrome.

Mechanisms of action of antipsychotic drugs of different classes, refractoriness to therapeutic effects of classical neuroleptics, and individual variation in sensitivity to their actions: Part II

Rapid-onset psychotic rebound is uncommon on discontinuation of most antipsychotic drugs, as might be expected for antipsychotic drugs with (hypothetically) indirect actions at their final target receptors. Rapid-onset psychosis is more common on withdrawal of clozapine, which might be expected if its action is direct. Drugs other than clozapine (notably thioridazine) may have hitherto unrecognised similarities to clozapine (but without danger of agranulocytosis), and may be useful in treatment of refractory psychosis. Quetiapine fulfils only some criteria for a clozapine-like drug. Clinical response to neuroleptics varies widely at any given plasma level. Haase's "neuroleptic threshold" concept suggests that the dose producing the slightest motor side effects produces most or all of the therapeutic benefit, but analyses presented here suggest that antipsychotic actions are not subject to a sharp "all-or-none" threshold but increase over a small dose range. This concept could provide a method for quantitative determination of individualized optimal doses.

Switching from conventional antipsychotics to ziprasidone: a randomized, open-label comparison of regimen strategies

In clinical psychopharmacology, the optimal method of switching from treatment A to treatment B with regard to efficacy and tolerability is an important area of study. We investigated the effects on efficacy and tolerability of switching patients from conventional antipsychotics to ziprasidone. This was a 6-week open-label, randomized study of 54 patients with persistent schizophrenia or schizoaffective disorder. Patients received ziprasidone 40 mg BID for 2 days, with titration up to 80 mg BID thereafter. The switch from conventional antipsychotics to ziprasidone was achieved using one of three discrete schedules: (1) abrupt discontinuation of conventional antipsychotics on day 1; (2) fast taper-50% of conventional antipsychotic dosage on days 1 through 7, followed by discontinuation and (3) slow taper-100% of conventional antipsychotic dosage on days 1 and 2, followed by 50% on days 3 through 7, then discontinuation. We found some evidence that the slow-taper strategy was associated with greater reductions in BPRS total scores early in the study compared to the other two strategies. However, these differences did not remain significant at endpoint, suggesting that there was no overall difference between the strategies.

An Unusual Cause of Delirium in a Psychiatric Patient: Abrupt Clozapine Discontinuation

Rapid clinical deteriorations have been reported after abrupt discontinuation of clozapine. A 42-year-old psychiatric patient presented with ingestion of hand-disinfectant solutions causing transient impairment of his conscious level. His clozapine therapy was discontinued for a short period of time and he developed delirium with normal results of investigations for underlying organic causes. His delirium resolved rapidly after the reintroduction of clozapine. The withdrawal effects of abrupt discontinuation of clozapine are discussed in this article.

Paralytic ileus associated with combined atypical antipsychotic therapy

First- and second-generation antipsychotics commonly cause mild and sometimes severe gastrointestinal motility depression. We discuss a case of a patient who developed paralytic ileus during his treatment with a combination of second-generation antipsychotics. The patient did not receive other medication that could cause depression of intestinal motility than the above-mentioned combination of antipsychotics and no other etiology could be found for the ileus. Furthermore we discuss the theoretical background of antipsychotics induced gastrointestinal motility depression and we provide the literature review of case reports of this topic.