Clozapine for treatment-resistant schizophrenia: National Institute of Clinical Excellence (NICE) guidance in the real world

Adherence to treatment guidelines in clinical practice: study of antipsychotic treatment prior to clozapine initiation

BACKGROUND

Clozapine is the only antipsychotic drug licensed for treatment-resistant schizophrenia but its use is often delayed. Since previous studies, national guidelines on the use of clozapine and other antipsychotics have been disseminated to clinicians.

AIMS

To determine the theoretical delay to clozapine initiation and to quantify the prior use of antipsychotic polypharmacy and high-dose antipsychotic treatment.

METHOD

Clinico-demographic data were extracted from the treatment records of all patients commencing clozapine in our centre between 2006 and 2010.

RESULTS

Complete records were available for 149 patients. The mean theoretical delay in initiating clozapine was 47.7 months (s.d. = 49.7). Before commencing clozapine, antipsychotic polypharmacy and high-dose treatment was evident in 36.2 and 34.2% of patients respectively. Theoretical delay was related to illness duration (β = 0.7, P<0.001) but did not differ by gender or ethnicity.

CONCLUSIONS

Substantial delays to clozapine initiation remain and antipsychotic polypharmacy and high doses are commonly used prior to clozapine, despite treatment guidelines.

The effect of clozapine on the AMPK-ACC-CPT1 pathway in the rat frontal cortex

Clozapine is an antipsychotic drug that has a greater efficacy than other medications in some contexts, especially for the treatment of treatment-resistant schizophrenia. However, clozapine induces more metabolic side-effects involving abnormality in lipid metabolism compared to other antipsychotics. AMP-activated protein kinase (AMPK) plays a central role in controlling lipid metabolism through modulating the downstream acetyl CoA carboxylase (ACC) and carnitine palmitoyl transferase 1 (CPT1) pathway. In this study, we investigated the effect of a single intraperitoneal injection of clozapine on the AMPK-ACC-CPT1 pathway in the rat frontal cortex, which has been implicated as a target site for this antipsychotic drug. At 2 h after injection, the clinically relevant dose of clozapine had activated AMPK, with increased phosphorylation of AMPKα at Thr(172), and had inactivated ACC, with increased phosphorylation of ACC at Ser(79). In addition, clozapine activated the brain-specific isoform of CPT1, CPT1c, whose activity is inhibited by unphosphorylated ACC, in the rat frontal cortex. Immunohistochemistry and immunofluorescence analysis showed that clozapine induced an increase in number of p-AMPKα (Thr(172))- and p-ACC (Ser(79))-positive cells among the neurons of the rat frontal cortex. Taken together, these results show that clozapine activated the AMPK-ACC-CPT1 pathway in the neurons of the rat frontal cortex. These findings indicate that the antipsychotic agent clozapine affects the lipid regulatory system of neurons in the brain.

Role of aripiprazole in treatment-resistant schizophrenia

About one third of patients with schizophrenia respond unsatisfactorily to antipsychotic treatment and are termed "treatment-resistant". Clozapine is still the gold standard in these cases. However, 40%-70% of patients do not improve sufficiently on clozapine either. In the search for more efficacious strategies for treatment-resistant schizophrenia, drugs with different pharmacological profiles seem to raise new hopes, but are they valid? The aim of this review was to evaluate the evidence for aripiprazole as a potential strategy in monotherapy or combination therapy for patients with treatment-resistant schizophrenia. The evidence for aripiprazole monotherapy and for the combination of aripiprazole with psychotropics other than clozapine is scant, and no recommendation can be made on the basis of the currently available data. More effort has been made in describing combinations of aripiprazole and clozapine. Most of the open-label and case studies as well as case reports have shown positive effects of this combination on overall psychopathology and to some extent on negative symptoms. Several reports describe the possibility of dose reduction for clozapine in combination with aripiprazole, a strategy that might help so-called "treatment-intolerant" patients. The findings of four randomized controlled trials with respect to changes in psychopathology seem less conclusive. The most commonly found beneficial effects are better metabolic outcomes and indicators of the possibility of reducing the clozapine dose. However, other side effects, such as akathisia, are repeatedly reported. Further, none of the studies report longer-term outcomes. In the absence of alternatives, polypharmacy is a common strategy in clinical practice. Combining aripiprazole with clozapine in clozapine-resistant or clozapine-intolerant patients seems to be worthy of further investigation from the pharmacological and clinical points of view.

QTc prolongation: is clozapine safe? Study of 82 cases before and after clozapine treatment

OBJECTIVE

The most feared cardiological consequence of clozapine is sudden cardiac death. A potential marker of it is QTc interval (QTc) prolongation. This study aimed to determine the prevalence of QTc prolongation in patients before and after 18 weeks of clozapine treatment and to detect predictors of QTc prolongation.

METHODS

Patients undergoing treatment with clozapine who had been given an electrocardiogram prior to the treatment and had their electrocardiogram, serum clozapine and norclozapine levels taken on the 18th week were selected. Exclusion criteria were thioridazine, pimozide, diuretics or beta-blocker treatment, electrolytic alteration, heart diseases and substance misuse diagnosis. Prolonged QTc was defined as >450 ms in men and >470 ms in women.

RESULTS

No significant differences were detected in prevalence of prolonged QTc or mean QTc before and after 18 weeks of clozapine treatment (p = 0.15, p = 0.32, respectively). Age, heart rate at 18th week and QTc prior to clozapine treatment had significant effects on QTc at follow-up. Prolonged QTc during previous treatment and heart rate >95 beats/min at 18 weeks were found to be predictors of QTc prolongation.

CONCLUSION

No significant differences were detected in prevalence of QTc prolongation or mean QTc among patients before and after 18 weeks on clozapine.

Antipsychotic polypharmacy in schizophrenia: benefits and risks

Antipsychotic polypharmacy refers to the co-prescription of more than one antipsychotic drug for an individual patient. Surveys of prescribing in psychiatric services internationally have identified the relatively frequent and consistent use of combined antipsychotics, usually for people with established schizophrenia, with a prevalence of up to 50% in some clinical settings. A common reason for prescribing more than one antipsychotic is to gain a greater or more rapid therapeutic response than has been achieved with antipsychotic monotherapy. However, the evidence on the risks and benefits for such a strategy is equivocal, and not generally considered adequate to warrant a recommendation for its use in routine clinical practice in psychiatry. Combined antipsychotics are a major contributor to high-dose prescribing, associated with an increased adverse effect burden, and of limited value in helping to establish the optimum maintenance regimen for a patient. The relatively widespread use of antipsychotic polypharmacy identified in cross-sectional surveys reflects not only the addition of a second antipsychotic to boost therapeutic response, but also the use of as-required antipsychotic medication (mainly to treat disturbed behaviour), gradual cross-titration while switching from one antipsychotic to another, and augmentation of clozapine with a second antipsychotic where the illness has failed to respond adequately to an optimized trial of clozapine. This review addresses the clinical trial data and other evidence for each of these pharmacological approaches. Also reviewed are examples of systematic, practice-based interventions designed to reduce the prevalence of antipsychotic polypharmacy, most of which have met with only modest success. Guidelines generally agree that if combined antipsychotics are prescribed to treat refractory psychotic illness, this should be after other, evidence-based, pharmacological treatments such as clozapine have been exhausted. Further, their prescription for each patient should be in the context of an individual trial, with monitoring of the clinical response and adverse effects, and appropriate physical health monitoring.

Evidence-based guidelines for the pharmacological treatment of schizophrenia: recommendations from the British Association for Psychopharmacology

These guidelines from the British Association for Psychopharmacology address the scope and targets of pharmacological treatment for schizophrenia. A consensus meeting, involving experts in schizophrenia and its treatment, reviewed key areas and considered the strength of evidence and clinical implications. The guidelines were drawn up after extensive feedback from the participants and interested parties, and cover the pharmacological management and treatment of schizophrenia across the various stages of the illness, including first-episode, relapse prevention, and illness that has proved refractory to standard treatment. The practice recommendations presented are based on the available evidence to date, and seek to clarify which interventions are of proven benefit. It is hoped that the recommendations will help to inform clinical decision making for practitioners, and perhaps also serve as a source of information for patients and carers. They are accompanied by a more detailed qualitative review of the available evidence. The strength of supporting evidence for each recommendation is rated.