Treatment of clozapine-induced constipation with bethanechol

Antipsychotic-Induced Constipation: A Review of the Pathogenesis, Clinical Diagnosis, and Treatment

Antipsychotic-induced gastrointestinal hypomotility and, in particular, its manifestation of constipation are common adverse effects in patients with schizophrenia in clinical practice. Serious complications of antipsychotic-induced constipation include ileus, ischaemic bowel disease, colon perforation, aspiration pneumonia, and bacterial septicaemia, which can be life threatening if left untreated, especially in patients prescribed clozapine. The aim of this paper is to review the latest research on the epidemiology, clinical examination methods, pathophysiology, and treatment options and preventive measures for antipsychotic-induced constipation. While clinicians are normally aware of the overall side effects caused by antipsychotics, constipation is often an under-recognized condition despite its relatively high incidence and its impact on daily living. The incidence of constipation differs among individual antipsychotics, but more than 50% of patients prescribed antipsychotics suffer from constipation. Limited fluid intake, poor dietary habits, and a sedentary lifestyle can also worsen constipation. The mechanisms of antipsychotic-induced constipation may be antagonism of cholinergic, histaminergic, and serotonergic receptors, with both parent drug and metabolite(s) contributing to the effects on gastrointestinal motility. Numerous methods, mainly divided into scale evaluations and objective examinations, are applied to evaluate antipsychotic-induced constipation; however, objective examinations have a greater ability to identify cases of gastrointestinal hypomotility since there is often an under-reporting of symptoms in subjective reporting and scale evaluation due to a higher pain threshold, an inability to express pain sensations, and a lack of symptom awareness in these patients. Antipsychotic drug-induced constipation should be closely monitored in patients receiving these medications, with timely intervention to avoid serious gastrointestinal consequences. There is currently no consensus on the efficacy of laxatives in these patients. Further in-depth studies should explore the underlying mechanisms and devise optimal therapeutic approaches to minimize constipation during antipsychotic treatment.

Managing Recurrent Clozapine-Induced Constipation in a Patient with Resistant Schizophrenia

Clozapine is an effective antipsychotic for the treatment of resistant schizophrenia. However, clozapine can lead to serious side effects. One of the most common side effects is constipation and in rare cases ileus, which is associated with a considerable case fatality rate. Our patient exhibited repeated episodes of ileus while being treated with clozapine. We adapted the treatment of the patient in several ways to manage these severe side effects. First, we reduced clozapine dosage by opting for an augmentation strategy of clozapine through paliperidone. Then, we added linaclotide as a nonconventional laxative. We further adapted treatment after the occurrence of a volvulus prompting surgical intervention which revealed a malformation of the intestines' peritoneal attachment. A gastrostomy to facilitate the treatment of any further episode was performed and bethanechol was introduced alongside linaclotide. Follow-up revealed the efficacy of our strategy involving the use of linaclotide in managing the side effects of clozapine in this patient.

Clozapine-Induced Constipation: A Case Report and Review of Current Management Guidelines

Clozapine is a second-generation antipsychotic recommended after the failure of two or more antipsychotics for treatment-resistant schizophrenia. Clozapine proved to also decrease recurrent suicidal behaviors in schizophrenia spectrum disorders. Yet, physicians often use clozapine as a last resort despite its proven efficacy due to its side effect profile. A noted side effect of clozapine is agranulocytosis, which requires a weekly complete blood count with differentials. Clozapine's anticholinergic activity causes colonic hypomotility, leading to constipation, and only a few studies examined clozapine-induced constipation (CIC). Few of the reported complications of CIC include bowel obstruction or bowel perforation due to fecal impaction. Herein we document a case report of CIC and also conducted a review of published case reports examining the complexity and management of CIC. CIC is a critical condition if unresolved as it can lead to mortality. Future directions and guidelines should be developed for early diagnosis and treatment for CIC, which will provide reassurance and directions for both the physicians and patients.

Clozapine: why wait to start a laxative?

Clozapine, the antipsychotic of choice for treatment-resistant schizophrenia, has a number of side-effects, some of which are potentially life-threatening. Historically viewed as a relatively minor side-effect, there is increasing awareness of the potentially severe sequalae of constipation secondary to clozapine-induced gastrointestinal hypomotility (CIGH). These include ileus, intestinal obstruction, bowel ischaemia, gastrointestinal necrosis, toxic megacolon and death. CIGH is significantly more common than clozapine-induced blood dyscrasias and has a higher mortality rate. Although strict criteria must be followed to assertively monitor, detect and treat blood dyscrasias in patients taking clozapine, no such framework exists for CIGH. We recommend that prescribing guidelines, regulatory agencies and information from manufacturers should more clearly highlight the risks identified in the literature. Furthermore, we recommend that, in people taking clozapine, constipation should be prevented by prophylactic treatment with laxatives rather than treated only when clinically identified.

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Clozapine-Associated Aspiration During Electroconvulsive Therapy

Clozapine-induced gastric hypomotility (CIGH) is an underreported, underrecognized effect from high-dose clozapine. In this report, we present a patient with treatment refractory schizophrenia receiving high-dose clozapine who aspirated during general anesthesia for electroconvulsive therapy. To our knowledge, this is the first report of aspiration under general anesthesia as a result of CIGH and highlights the potential dangers high-dose clozapine can pose on patients undergoing electroconvulsive therapy with unrecognized CIGH.

Clozapine and Gastrointestinal Hypomotility

Gastrointestinal hypomotility (GIH) is an under-reported but highly prevalent and potentially dangerous side effect of clozapine. In a comprehensive meta-analysis of clozapine-treated patients, the prevalence of GIH was 32%. In general, GIH has consistently been reported to have a negative impact on quality of life, and there is no reason to believe this will be different in clozapine-treated patients with therapy-resistant schizophrenia. GIH is dangerous; in a comparative review of lethal side effects of clozapine, the mortality of agranulocytosis was 2.2-4.2% compared with 15.0-27.5% for GIH. The mortality rate in our review of all published case reports of ileus was 43.7%. (Co-)Prescription of anticholinergic drugs in patients treated with clozapine should be avoided as anticholinergics are associated with increased incidence and fatality of ileus. Prevention of GIH can best be obtained by frequent and targeted questioning by the mental healthcare providers of the patients' defecation pattern and this is therefore strongly recommended for timely detection and treatment of treatment-emergent GIH throughout clozapine treatment. Treatment approaches can be either preventive laxative prescription with every clozapine prescription in all clozapine-treated patients or targeted treatment of treatment-emergent GIH. First-line treatments of GIH are the osmotic laxative macrogol, stool softener docusate and bowel stimulant senna. As the occurrence of severe cases of GIH is not restricted to a certain treatment duration, alertness for and/or treatment of GIH is required for the whole duration of clozapine treatment.

Trends in the prescription of clozapine in a psychiatric hospital: a 5-year observational study

INTRODUCTION

Clozapine is a well-recognized effective treatment for some patients with treatment-resistant schizophrenia (TRS). Although it has potential benefits and approximately 30% of patients have a clinical indication for clozapine use, prescription rates are low.

OBJECTIVE

To evaluate clozapine prescription trends over a 5-year period in a tertiary psychiatric hospital.

METHODS

In this observational study, data prospectively collected by the Medical and Statistical File Service (Serviço de Arquivo Médico e Estatístico) and the Pharmacy Division of Instituto de Psiquiatria de Santa Catarina between January 2010 and December 2014 were summarized and analyzed by investigators blinded to data collection. The number of 100 mg clozapine pills dispensed by the Pharmacy Division to the inpatient units was the outcome and considered a proxy measure of clozapine prescriptions. The number of occupied inpatient unit beds and the number of patients admitted with F20-F29 (ICD-10) diagnoses during the study period were considered to be possible confounders.

RESULTS

A multiple linear regression model showed that time in months was independently associated with an increase in the number of clozapine pills dispensed by the Pharmacy Division (β coefficient = 15.82; 95% confidence interval 10.88-20.75).

CONCLUSION

Clozapine prescriptions were found to have increased during the 5-year period studied, a trend that is opposite to reports from several other countries.

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).

Prevalence and Predictors of Clozapine-Associated Constipation: A Systematic Review and Meta-Analysis

Constipation is a frequently overlooked side effect of clozapine treatment that can prove fatal. We conducted a systematic review and meta-analysis to estimate the prevalence and risk factors for clozapine-associated constipation. Two authors performed a systematic search of major electronic databases from January 1990 to March 2016 for articles reporting the prevalence of constipation in adults treated with clozapine. A random effects meta-analysis was conducted. A total of 32 studies were meta-analyzed, establishing a pooled prevalence of clozapine-associated constipation of 31.2% (95% CI: 25.6-37.4) (n = 2013). People taking clozapine were significantly more likely to be constipated versus other antipsychotics (OR 3.02 (CI: 1.91-4.77), p < 0.001, n = 11 studies). Meta-regression identified two significant study-level factors associated with constipation prevalence: significantly higher (p = 0.02) rates of constipation were observed for those treated in inpatient versus outpatient or mixed settings and for those studies in which constipation was a primary or secondary outcome measure (36.9%) compared to studies in which constipation was not a specified outcome measure (24.8%, p = 0.048). Clozapine-associated constipation is common and approximately three times more likely than with other antipsychotics. Screening and preventative strategies should be established and appropriate symptomatic treatment applied when required.

Colonic transit diagnostic test shows significant gastrointestinal hypomotility in clozapine-treated patients in comparison with subjects treated with other antipsychotics

BACKGROUND

Constipation occurs in 25-60% of the subjects during administration of the antipsychotic drug (AP) clozapine (CLZ).

METHODS

We used a colonic transit diagnostic test that quantifies in a single abdominal X-ray the number of silver O-ring markers out of 25 units ingested five days before. The quantity of markers is directly proportional to the degree of gastrointestinal hypomotility, and elimination of over 80% of the markers is considered normal. The test was applied to three groups of AP-treated subjects for at least three consecutive months: CLZ alone (n=45), CLZ+Other APs (n=28), and Other APs (n=64).

RESULTS

The number of remaining markers at day 5 (mean±S.D.) was significantly higher in the CLZ alone (10.8±10.6) and in the CLZ+Other APs (9.7±9.7) groups than in the Other AP group (4.5±6.7), Kruskal-Wallis test: p=0.004. No significant associations were found between the number of markers, age, AP dose and treatment duration. All subjects who passed <80% of markers - which approximately corresponds to the 60th percentile of marker elimination - showed a scattered marker distribution along the colon, thus suggesting colon inertia. In subjects with hypomotility, 38.5% of the CLZ group, 25% of the CLZ+Other APs group, and 25% of the Other APs group were negative for the Rome III clinical criteria of constipation, thus showing objective, not subjective, hypomotility.

CONCLUSIONS

This study objectively confirms significant gastrointestinal hypomotility associated with CLZ administration.