Hyoscine for clozapine-induced hypersalivation: a double-blind, randomized, placebo-controlled cross-over trial

Analysis of clinical studies on clozapine from 2012-2022

Clozapine has been considered the "gold standard" in the treatment of schizophrenia for many years. Clozapine has a superior effect, particularly in the treatment of negative symptoms and suicidal behaviour. However, due to its numerous adverse reactions, clozapine is mainly used for treatment-resistant schizophrenia. The aim of this paper is to analyze the results of clinical studies on clozapine from 2012-2022. PubMed was used as the database. Sixty-four studies were included and categorised by topic. The pharmacokinetic properties of clozapine tablets and a clozapine suspension solution did not differ markedly. Clozapine was superior to olanzapine and risperidone in reducing aggression and depression. A long-term study showed that metabolic parameters changed comparably with olanzapine and clozapine after 8 years. Risperidone and ziprasidone can be used as an alternative to clozapine. Scopolamine, atropine drops, and metoclopramide are effective in the treatment of clozapine-induced hypersalivation. Eight drugs, including liraglutide, exenatide, metformin, and orlistat, are potentially effective in the treatment of clozapine-induced weight gain. Ziprasidone, haloperidol, and aripiprazole showed a positive effect on symptoms when added to clozapine. No investigated drug was superior to clozapine for the treatment of schizophrenia. Ziprasidone and risperidone can also be used well for the treatment of schizophrenia. In the treatment of clozapine-induced hypersalivation and weight gain, some drugs proved to be effective.

Pharmacological interventions for antipsychotic-related sialorrhea: a systematic review and network meta-analysis of randomized trials

Antipsychotic-induced sialorrhea carries a significant burden, but evidence-based treatment guidance is incomplete, warranting network meta-analysis (NMA) of pharmacological interventions for antipsychotic-related sialorrhea. PubMed Central/PsycInfo/Cochrane Central database/Clinicaltrials.gov/WHO-ICTRP and the Chinese Electronic Journal Database (Qikan.cqvip.com) were searched for published/unpublished RCTs of antipsychotic-induced sialorrhea (any definition) in adults, up to 06/12/2023. We assessed global/local inconsistencies, publication bias, risk of bias (RoB2), and confidence in the evidence, conducting subgroup/sensitivity analyses. Co-primary efficacy outcomes were changes in saliva production (standardized mean difference/SMD) and study-defined response (risk ratios/RRs). The acceptability outcome was all-cause discontinuation (RR). Primary nodes were molecules; the mechanism of action (MoA) was secondary. Thirty-four RCTs entered a systematic review, 33 NMA (n = 1958). All interventions were for clozapine-induced sialorrhea in subjects with mental disorders. Regarding individual agents and response, metoclopramide (RR = 3.11, 95% C.I. = 1.39-6.98), cyproheptadine, (RR = 2.76, 95% C.I. = 2.00-3.82), sulpiride (RR = 2.49, 95% C.I. = 1.65-3.77), propantheline (RR = 2.39, 95% C.I. = 1.97-2.90), diphenhydramine (RR = 2.32, 95% C.I. = 1.88-2.86), benzhexol (RR = 2.32, 95% C.I. = 1.59-3.38), doxepin (RR = 2.30, 95% C.I. = 1.85-2.88), amisulpride (RR = 2.23, 95% C.I. = 1.30-3.81), chlorpheniramine (RR = 2.20, 95% C.I. = 1.67-2.89), amitriptyline (RR = 2.09, 95% C.I. = 1.34-3.26), atropine, (RR = 2.03, 95% C.I. = 1.22-3.38), and astemizole, (RR = 1.70, 95% C.I. = 1.28-2.26) outperformed placebo, but not glycopyrrolate or ipratropium. Across secondary nodes (k = 28, n = 1821), antimuscarinics (RR = 2.26, 95% C.I. = 1.91-2.68), benzamides (RR = 2.23, 95% C.I. = 1.75-3.10), TCAs (RR = 2.23, 95% C.I. = 1.83-2.72), and antihistamines (RR = 2.18, 95% C.I. = 1.83-2.59) outperformed placebo. In head-to-head comparisons, astemizole and ipratropium were outperformed by several interventions. All secondary nodes, except benzamides, outperformed the placebo on the continuous efficacy outcome. For nocturnal sialorrhea, neither benzamides nor atropine outperformed the placebo. Active interventions did not differ significantly from placebo regarding constipation or sleepiness/drowsiness. Low-confidence findings prompt caution in the interpretation of the results. Considering primary nodes' co-primary efficacy outcomes and head-to-head comparisons, efficacy for sialorrhea is most consistent for the following agents, decreasing from metoclopramide through cyproheptadine, sulpiride, propantheline, diphenhydramine, benzhexol, doxepin, amisulpride, chlorpheniramine, to amitriptyline, and atropine (the latter not for nocturnal sialorrhea). Shared decision-making with the patient should guide treatment decisions regarding clozapine-related sialorrhea.

Treatment of Clozapine-Associated Sialorrhea: The Role of Benzamide Derivatives

PURPOSE

Hypersalivation is one of the most prevalent and distressing adverse effects associated with clozapine treatment. Currently, there is no standard therapeutic approach toward how to overcome it. Clinicians use various medications for managing this adverse effect. However, some of the agents are not effective enough, whereas others can induce other adverse effects. Recently, several reviews have been published on the treatment of clozapine-associated hypersalivation, in which the focus was on drugs from various pharmacological groups, and little attention was paid to drugs from the group of substituted benzamides. The intention of this brief narrative review is to draw the attention of clinicians to the use of the benzamide group for the treatment of this unpleasant adverse effect.

METHODS

A MEDLINE search was conducted to identify published treatment studies and case reports in the literature from 2000 to September 2021, concerning a treatment of clozapine-associated hypersalivation, mainly substituted benzamides.

RESULTS

Accumulating evidence during the last 2 decades indicates that agents derived from the benzamide group may be effective and safe agents for treatment of clozapine-associated hypersalivation. Whether with a psychotropic effect or without, medications from this group may produce a beneficial response.

CONCLUSIONS

Substitute benzamide derivatives have emerged as effective and well-tolerated agents for treatment clozapine-associated hypersalivation.

Clinical Effectiveness of Muscarinic Receptor-Targeted Interventions in Neuropsychiatric Disorders: A Systematic Review

BACKGROUND

For decades, treatment of mood disorders, psychoses, anxiety and dementia have been confounded by limited efficacy and high rates of treatment resistance. Preclinical and clinical evidence have highlighted disruption of cholinergic signalling in several neuropsychiatric conditions and examined intervention strategies including acetylcholinesterase inhibitors and nicotinic receptor-targeted intervention. However, the effectiveness of these approaches is often curtailed by on-target side effects. Post mortem studies implicate muscarinic receptor dysregulation in neuropsychiatric pathophysiology; therefore, we conducted a systematic review and meta-analysis to investigate the therapeutic efficacy and safety of muscarinic receptor-targeted interventions in adults with neuropsychiatric disorders.

METHODS

PubMed, EMBASE, PsycINFO, EBSCO and Web of Science were searched using relevant keywords from database inception to 7 August 2022. Randomised, double-blind, placebo-controlled studies were included if they investigated the effect of muscarinic receptor-targeted intervention in adults with a diagnosis of a neuropsychiatric disorder and were published in English. A narrative synthesis approach was adopted to describe the findings. Wherever three or more studies with a similar intervention were available, effect sizes were calculated, and a meta-analysis was performed. Cochrane risk-of-bias-2 tool was utilised to assess the risk of bias, and sensitivity analyses were performed to identify publication bias. Certainty analysis (high, moderate, low and/or very low) was conducted using GRADE criteria.

RESULTS

Overall, 33 studies met the inclusion criteria and 5 were included in the meta-analysis. Despite a limited pool with several different interventions, we found therapeutic efficacy of xanomeline (M₁/M₄ agonist) in primary psychotic disorders plus behavioural and psychological symptoms of dementia. Scopolamine showed a significant antidepressant effect in a combined cohort of major depressive and bipolar disorders in the short-term outcome measure, but no effect following cessation of treatment. Results from bias assessments suggest "very low" certainty in the antidepressant effect of scopolamine. Critical limitations of the current literature included low power, high heterogeneity in the patient population and a lack of active comparators.

CONCLUSION

While the results are not definitive, findings on muscarinic receptor-targeted interventions in several mental disorders are promising in terms of efficacy and safety, specifically in treating schizophrenia, mood disorders, and behavioural and psychiatric symptoms of Alzheimer's disease. However, orthosteric muscarinic receptor-targeted interventions are associated with a range of peripheral adverse effects that are thought to be mediated via M₂/M₃ receptors. The orthosteric binding site of muscarinic acetylcholine receptors is remarkably conserved, posing a challenge for subtype-selective interventions; nonetheless allosteric ligands with biased signalling pathways are now in development. We conclude that adequately powered prospective studies with subtype-selective interventions are required to determine the clinical effectiveness of muscarinic-receptor targeted interventions for the treatment of neuropsychiatric disorders.

Clozapine prescribing: comparison of clozapine dosage and plasma levels between White British and Bangladeshi patients

AIMS AND METHOD

To compare differences in clozapine doses and plasma levels between Bangladeshi and White British patients. Following ethical approval we identified all current Bangladeshi and White British patients on clozapine maintenance in an east London clinic. We carried out univariate and multivariate regression analyses to examine associations between clozapine doses and ethnicity, age, gender, smoking status and weight. We also compared plasma clozapine levels of the two groups.

RESULTS

On univariate analysis White British patients had on average 85 mg higher doses than Bangladeshi patients (P = 0.004). Older age, male gender and smoking were also associated with higher dose. On multivariate analysis only age and smoking status remained significant. A greater proportion of Bangladeshi patients had high plasma clozapine levels compared with White British (30.76% v. 20.75%), although the difference was not statistically significant.

CLINICAL IMPLICATIONS

Our findings point to the need for the broadening of data collection on ethnic differences in clozapine prescribing within big data-sets such as Prescribing Observatory for Mental Health (POM-UK). Ethnopharmacological variations can inform more person-centred guidance on prescribing.

The effect of sublingual atropine sulfate on clozapine-induced hypersalivation: a multicentre, randomised placebo-controlled trial

BACKGROUND

Hypersalivation and drooling are commonly reported in clozapine-treated patients. Current management strategies have been evaluated using subjective measures. Many case reports describe the successful use of atropine in the treatment of the condition.

AIMS

To measure the effect and safety of sublingual atropine on nocturnal unstimulated saliva secretion. Secondary aims were to evaluate the patient's satisfaction with the atropine effect on hypersalivation (or sialorrhea), drooling, and sleep.

METHOD

Twenty-one clozapine-treated patients with hypersalivation, or drooling, were randomised to take a single 600-μg dose of sublingual atropine drops or a matching placebo. The saliva secretion was measured over 5 min at baseline and 2 h after the administration of the study medication.

RESULTS

Sublingual atropine reduced the saliva secretion significantly more than the placebo (mean difference = - 57.21%, 95% CI: - 104.30, - 10.11, P = 0.02). A significant decrease in standing pulse rate was recorded in the participants in the atropine group (- 5.8 (- 9.54, - 2.15), P = 0.002). Subjectively, more patients in the atropine group found their pillow to have less saliva the following morning and found their sleep to be better.

CONCLUSIONS

Sublingual atropine drops significantly reduces nocturnal unstimulated clozapine-induced saliva secretion. More research is required to compare the effect of sublingual atropine with other anticholinergic medications and different dosage forms.

TRIAL REGISTRATION

ACTRN12618000051246.

Glycopyrrolate in comparison to hyoscine hydrobromide and placebo in the treatment of hypersalivation induced by clozapine (GOTHIC1): a feasibility study

Background

Clozapine-induced hypersalivation (CIH) is a common side effect of clozapine treatment and is disliked by clozapine patients, potentially threatening adherence to clozapine treatment. We proposed a trial of alternative medications, hyoscine and glycopyrrolate, for the treatment of CIH and the primary objective of the feasibility study was to assess the recruitment and retention of community clozapine patients as well as assess the metrics of the primary hypersalivation measure.

Methods

This 11-month trial took place in two NHS trusts in northwest UK. Participants were community-dwelling clozapine patients aged 18–65 years who were suffering from CIH, and were recruited from community mental health clinics. They were randomised using a telephone randomisation service to receive either hyoscine (1 week at 0.6 mg daily, 3 weeks at 0.9 mg daily), glycopyrrolate (1 week at 2 mg daily, 3 weeks at 3 mg daily) or placebo. Participants and investigators were blinded to which study arm the participants had been randomised to. We collected data on salivation levels and side effects on a weekly basis and also assessed cognition at the beginning and end of the trial. We also interviewed a sample of participants after the trial to gather information on their experience of having taken part.

Results

One hundred and thirty-eight potential participants agreed to being contacted by researchers about participation in the trial and of these, 29 participants were randomised. Of these, four participants exited the trial before taking any trial medication, and two participants left the study owing to concerns of side effects. Data from four participants was missing, and complete data was available for 19 participants who completed the trial. The mean recruitment rate overall was 1.3 participants per site per month, and the overall retention rate was 76%. Interview data suggested that participants’ experiences of trial participation were overwhelmingly positive.

Conclusions

The feasibility study demonstrated that a trial of alternative medications in the treatment of CIH is feasible; patients were willing to be randomised to the trial and retention rate was high.

Trial registration

ClinicalTrials.gov, NCT02613494, registered 24 November 2015