Combination treatment with clozapine and paroxetine in schizophrenia: safety and tolerability data from a prospective open clinical trial

Optimizing antidepressant and clozapine co-prescription in clinical practice: A systematic review and expert recommendations

OBJECTIVES

To synthesize the information relevant for clinical practice on clozapine-antidepressant co-prescription concerning pharmacokinetic drug-drug interactions (DDI), adverse drug reactions (ADRs) associated with the co-prescription, antidepressant add-on for clozapine-resistant symptoms and antidepressant add-on for clozapine-induced ADRs.

METHODS

Articles were identified with MEDLINE, Web of Sciences and PsycINFO search from inception through April 2023. Data were synthesized narratively.

RESULTS

ADRs are most often induced by the co-prescription of antidepressants that inhibit CYP enzymes (fluvoxamine, fluoxetine, paroxetine). Fluvoxamine add-on is hazardous because of its potent inhibition of clozapine metabolism and has few indications (lowering daily number of clozapine tablets, reducing norclozapine-induced metabolic disturbances and other dose-dependent clozapine-induced ADRs). ADR frequency may be reduced by therapeutic drug monitoring and knowledge of other factors impacting clozapine metabolism (pneumonia, inflammation, smoking, etc.). Improvement of negative symptoms is the most documented beneficial effect of antidepressant add-on for clozapine-resistant psychotic symptoms. The add-on antidepressant should be chosen according to its safety profile regarding DDI with clozapine: antidepressants inhibiting clozapine metabolism or increasing the anticholinergic load should be avoided. Other indications of antidepressant add-on (affective or obsessive compulsive symptoms, sialorrhea, and enuresis) are poorly documented.

CONCLUSION

Antidepressant add-on to clozapine is associated with potential benefits in clozapine users as this strategy may contribute to reduce the burden of clozapine-resistant symptoms or of clozapine-induced ADRs. Further studies are needed to determine whether antidepressant add-on can reduce the risk of clozapine discontinuation.

Characteristics and definitions of ultra-treatment-resistant schizophrenia - A systematic review and meta-analysis

OBJECTIVE

The aim of this systematic review and meta-analysis was to characterize ultra-treatment-resistant Schizophrenia also known as clozapine-resistant schizophrenia (CRS) patients across clozapine combination and augmentation trials through demographic and clinical baseline data. Furthermore, we investigated the variability and consistency in CRS definitions between studies.

METHODS

Systematic searches of articles indexed in PubMed, EMBASE, the Cochrane Central Register of Controlled Trials (CENTRAL) and PsycINFO were conducted in March 2020. 1541 randomized and non-randomized clinical trials investigating pharmacological and non-pharmacological clozapine add-on strategies were screened and a total of 71 studies were included. The primary outcome was the overall symptom score at baseline, measured with Positive and Negative Syndrome Scale (PANSS) total or Brief Psychiatric Rating Scale (BPRS) total scores.

RESULTS

Data from 2731 patients were extracted. Patients were overall moderately ill with a mean PANSS total score at baseline of 79.16 (±7.52), a mean duration of illness of 14.64 (±4.14) years with a mean clozapine dose of 436.94 (±87.47) mg/day. Illness severity data were relatively homogenous among patients independently of the augmentation strategy involved, although stark geographical differences were found. Overall, studies showed a large heterogeneity of CRS definitions and insufficient guidelines implementation.

CONCLUSIONS

This first meta-analysis characterizing CRS patients and comparing CRS definitions revealed a lack of consistent implementation of a CRS definition from guidelines into clinical trials, compromising the replicability of the results and their applicability in clinical practice. We offer a new score modeled on a best practice definition to help future trials increase their reliability.

Augmentation strategies in partial responder and/or treatment-resistant schizophrenia patients treated with clozapine

INTRODUCTION

Although clozapine (CLZ) is considered the best evidence-based therapeutic option for treatment of resistant schizophrenia patients, a significant proportion of CLZ-treated patients show a partial or inadequate response to treatment, leading to increased healthcare cost and poor quality of life for affected individuals.

AREAS COVERED

This paper comprises a review of main research in CLZ augmentation strategies for treatment-refractory schizophrenia, with a focus on research conducted between 1990 and 2014. Databases that were searched include: PubMed, CINAHL, EMBASE PsychINFO, AgeLine and Cochrane Database of Systematic Reviews. Primary search terms were 'clozapine augmentation', 'clozapine and add-on' and 'treatment-resistant schizophrenia', with cross reference to specific agents covered in this article. We reviewed the available evidence on CLZ augmentation with antipsychotics, antidepressants, mood stabilizers and other agents.

EXPERT OPINION

Many drugs have been evaluated as CLZ add-on therapies without demonstrating convincing efficacy in treating refractory schizophrenia symptoms. More research is needed to better define outcomes in schizophrenia, the topic of treatment-resistance and more well-designed trials are required to establish true efficacy and safety of CLZ augmentation strategies.

Leukopenia Associated with Paroxetine Use

Objective:

To report a case of leukopenia associated with paroxetine treatment.

Case Summary:

A 44-year-old white female with a history of anemia secondary to heavy menses, anxiety, depression, and current tobacco dependence presented with general symptoms of fatigue and blurred vision. The patient's medications at the time of the initial visit were ferrous sulfate 325 mg twice a day and paroxetine 20 mg/day. Three years prior to the initiation of paroxetine, the patient's documented white blood cell (WBC) count was 7.4 × 103/ μL with normal differential and hemoglobin was 10.5 g/dL; on presentation, laboratory test results were WBC count 1.3 × 103/ μL, red blood cell count 1.78 × 106/ μL, hemoglobin 4.5 g/dL, hematocrit 15.1%, and platelets 248 × 103/ μL. Three months after discontinuation of paroxetine, the patient's WBC count was 4.4 × 103/ μL.

Discussion:

Paroxetine and other antidepressants have not been known to cause adverse hematologic effects that can be seen with other antipsychotics, namely, clozapine. The use of the Naranjo probability scale indicated a probable relationship between leukopenia and paroxetine therapy in this patient. Based on a MEDLINE search (February 12, 2007), there are limited data on leukopenia as an adverse event of paroxetine. We found this to be a unique case of leukopenia suspected to be secondary to extended use of low-dose paroxetine.

Conclusions:

Although leukopenia caused by paroxetine and other medications with serotonergic effects appears to be uncommon, physicians and pharmacists should be aware of this rare but potentially serious adverse event.

Somatic augmentation strategies in clozapine resistance--what facts?

BACKGROUND

Polypharmacy without evidence-based support is sometimes needed for patients treated with 40% to 70% clozapine who are clozapine nonresponders. Several somatic augmentation strategies are proposed in the scientific literature, with different levels of evidence for safety and efficacy.

OBJECTIVES

The purpose of the present study is to review the available literature on the efficacy and safety of clozapine augmentation with somatic agents other than antipsychotics. The following classes of agents are considered: (1) mood stabilizers, (2) antidepressants, (3) electroconvulsive therapy and repetitive transcranial magnetic stimulation, (4) glutamatergic agents, (5)fatty acids supplements, and (6) benzodiazepines.

RESULTS

Case controls and small-size clinical trials largely dominate the literature, limiting the power to draw conclusions concerning safety issues and the meaning of negative studies. Moreover, variable definitions of clozapine resistance, heterogeneous outcome measures, and short duration of treatment trials are additional limitations.

CONCLUSION

Generally, adjunctive strategies for clozapine-resistant patients remain based on scarce evidence of efficacy and significant safety concerns. Low-frequency repetitive transcranial magnetic stimulation, fatty acids supplements, and mirtazapine showed good tolerability and some efficacy, but the results need replication.

Fluvoxamine augmentation in risperidone-resistant schizophrenia: an open trial

We investigated the efficacy and safety of augmenting risperidone with fluvoxamine for the treatment of residual positive and negative symptoms in patients with chronic schizophrenia who had shown an incomplete response to risperidone. A total of 30 patients completed the open trial over a 12-week period during which fluvoxamine was added to risperidone. The result from the positive and negative syndrome scale (PANSS) and Simpson-Angus extrapyramidal effects (S-A) scale were examined at baseline, 1, 2, 4, 8 and 12 weeks of treatment. There were no significant differences in PANSS positive, negative and general psychopathology scores, or in S-A scale scores at any point during the treatment. These results suggest that fluvoxamine appears to be ineffective in augmenting the risperidone treatment response in chronic schizophrenic patients. Further controlled trials will be needed to confirm this observation.

Fluoxetine prevents PCP- and MK801-induced HSP70 expression in injured limbic cortical neurons of rats

BACKGROUND

N-Methyl-D-aspartate (NMDA) receptor antagonists, including phencyclidine (PCP) and dizocilpine (MK801), cause schizophrenialike psychosis in humans, and produce vacuolated neurons in the cingulate and retrosplenial cortices of the rat brain. Since psychotically depressed patients and schizophrenic depressed patients may require treatment with selective serotonin reuptake inhibitors (SSRIs), it is of interest to examine the relationship between SSRIs and NMDA antagonist neurotoxicity.

METHODS

The neurotoxicity of PCP and MK801 was assessed using heat shock protein (HSP70) immunocytochemistry and HSP70 Western blots because HSP70 is expressed in the injured, vacuolated neurons. Female rats were given fluoxetine (0, 5, 10, and 20 mg/kg IP) followed 1 hour later by MK801 (1 mg/kg IP) or PCP (50 mg/kg IP).

RESULTS

Pretreatment with fluoxetine (20 mg/kg IP) 1 hour before MK801 prevented the induction of HSP70 by MK801 in the cingulate and retrosplenial cortices. Pretreatment with fluoxetine (10 or 20 mg/kg IP) 1 hour before PCP also prevented the HSP70 induction by PCP.

CONCLUSIONS

Fluoxetine prevents the neurotoxicity of NMDA receptor antagonists in rat brain. This suggests the possibility that SSRIs could modulate psychosis, and may provide a model for examining the link between the hallucinogenic properties of PCP and lysergic acid diethylamide.