Pharmacoclinical strategy in neuroleptic resistant schizophrenic patients treated by clozapine: clinical evolution, concentration of plasma and red blood cell clozapine and desmethylclozapine, whole blood serotonin and tryptophan

Blood-based kynurenine pathway alterations in schizophrenia spectrum disorders: A meta-analysis

INTRODUCTION

The kynurenine pathway (KP) has been proposed as indirect link between systemic immune responses and clinical symptom development in schizophrenia spectrum disorders (SSD). Empirical evidence for such immune-related KP shifts in SSD has however resulted in divergent findings.

METHODS

We conducted a systematic literature search in PubMed. Thirty papers (total number of patients n = 1506; controls: n = 1432) reported on peripheral concentrations of KP metabolites in SSD patients versus controls. Six KP metabolites were included in a meta-analysis, with secondary analysis of covariate and subgroup effects of patients' symptomatic state, age and duration of illness.

RESULTS

Tryptophan (SMD: -0.30; p = .003) and Xanthurenic Acid (SMD: -0.80; p < .001) were significantly decreased in SSD compared to controls, while Quinolinic Acid (SMD: -0.40; p = .08) and Kynurenic Acid (SMD: -0.39; p = .04) were only significantly decreased in patients with acute or highly symptomatic illness. Finally, in relatively older patient cohorts Kynurenine (SMD: -0.31; p = .02) and Kynurenic Acid (SMD: -0.40; p = .002) were found to be decreased.

CONCLUSION

A partial downregulation of the KP is observed in SSD patients, in particular during acute symptomatic states and in older age, effects that were independent from each other. In contrast, younger and stable or remitted patients display limited to no KP metabolite abnormalities. The current meta-analysis illustrates the dynamic nature of KP abnormalities. It should be noted that all included studies investigated peripheral KP metabolites, which do not necessarily reflect central KP metabolite abnormalities in schizophrenic patients.

Lipid status, anti-oxidant enzyme defence and haemoglobin content in the blood of long-term clozapine-treated schizophrenic patients

OBJECTIVE

Despite clozapine's unique effectiveness in patients with schizophrenia, a number of adverse effects have been recognised including abnormalities in lipid and glucose metabolisms. A high clozapine level in red blood cells (RBCs) and disturbed anti-oxidant enzyme activities in blood from schizophrenic patients prompted us to investigate lipid status and anti-oxidant enzyme defence in the blood of chronic schizophrenic patients on long-term clozapine therapy.

METHODS

Plasma lipids, RBC anti-oxidant enzyme activities and haemoglobin (Hb) content were measured using established procedures in a group of eighteen chronically-medicated (average 630 days of therapy) schizophrenic patients receiving clozapine (average dose of 295 mg/day) and data were compared with those from a group of eighteen well-matched normal controls.

RESULTS

Significantly higher levels of plasma triglycerides (by 47%, p<0.01) and total cholesterol and phospholipids (by 8% and 11%, respectively p<0.05) in patients were found. CuZn-superoxide dismutase (SOD1) activity was markedly higher (by 35%, p<0.001) while selenium-dependent glutathione peroxidase (GSH-Px1) activity was markedly lower (by 41%, p<0.001) in patients. In addition, metHb and HbA1c levels in patients were significantly higher (by 58% and 25%, respectively p<0.001). SOD1 activity was negatively correlated (p<0.001) to GSH-Px1 activity in patients.

CONCLUSIONS

The findings support the view that ongoing oxidative stress may be a mechanism by which clozapine induces some adverse effects that increase the risk of diabetes and metabolic syndrome. If valid, this would indicate that in parallel with long-term clozapine treatment, schizophrenic patients could be encouraged to make some lifestyle changes to limit the detrimental effects of the medication.

Lower levels of whole blood serotonin in obsessive-compulsive disorder and in schizophrenia with obsessive-compulsive symptoms

It has been reported that some schizophrenic patients suffer from obsessive-compulsive symptoms (OCS), and clozapine treatment is quite often associated with an occurrence/increase of OCS in schizophrenic patients. The aim of the study was to explore whether differences would exist in the clinical symptomatology and the whole blood serotonin (5-HT) concentrations in patients with obsessive-compulsive disorder (OCD), schizophrenic patients with and without OCS (S+OCS, S-OCS), and clozapine-treated schizophrenic patients with and without clozapine-induced OCS (CLZ+OCS, CLZ-OCS). We found that S+OCS patients (n=15) showed significantly lower scores on the Hamilton Anxiety Scale (HAMA), but similar levels of compulsions and obsessions using Yale-Brown Obsessive-Compulsive Scale (YBOCS) as compared to the patients (n=35) with OCD. S+OCS patients scored significantly lower on the Positive and Negative Syndrome Scale (PANSS) but higher on the Hamilton Depression Scale (HAMD) compared with S-OCS patients (n=19). However, CLZ+OCS patients (n=15) suffered from dominant compulsions but fewer obsessions compared with the OCD and S+OCS patients. OCD, S+OCS and CLZ+OCS groups had significantly lower levels of whole blood 5-HT than did the healthy volunteers (n=15), S-OCS and CLZ-OCS groups. It suggests that alterations in serotonin metabolism may be a common biological characteristic of OCS in OCD as well as in schizophrenia.

Intérêt des antidépresseurs chez le patient schizophrène présentant un syndrome dépressif

INTRODUCTION

Depression is common in people with schizophrenia and is associated with substantial morbidity explaining also the considerable attention and recognition of this entity as suggested by the inclusion of the post-psychotic depression in DSM IV and ICD 10. The prevalence of this disorder varies according to the type of approach used (range between 7% to 75%). Prescription of antidepressants plus antipsychotic treatment is frequent in clinical practice (11 to 43%).

BACKGROUND

Pharmacokinetic and metabolic interactions have been identified. The cytochrome P450 has been identified as being implicated in the metabolism of most psychotropics, mainly through the CYP1A2, CYP2C19, CYP2D6, CYP3A4 isoenzymes. Tricyclic antidepressants are likely to increase chlorpromazine plasma levels. Similarly, antipsychotics such as perphenazine, chlorpromazine or haloperidol can increase antidepressant plasma levels, through the inhibition of CYP 450 isoenzymes (CYP2D6). Most of the Specific Serotonin Recapture Inhibitors (SSRIs) are likely to inhibit one or several CYP450 isoenzymes. The inhibition is moderate to marked for CYP1A2 (fluvoxamine and fluoxetine), CYP2C19 (fluoxetine, fluvoxamine and sertraline), CYP2D6 (paroxetine, fluoxetine and sertraline), and CYP3A4 (fluvoxamine, fluoxetine and sertraline). In the US, one-fourth of psychiatrists report the use of depression-rating scales in schizophrenic patients. Non specific scales (Hamilton Depression Rating Scale or Beck Depression Inventory) are the most commonly used in spite of the fact that these scales do not allow the distinction of depressive from negative symptoms in schizophrenic patients.

LITERATURE FINDINGS

Due to these limitations, more specific assessment tools for depressive symptoms in schizophrenia are required. Two specific scales for assessing depressive symptoms in schizophrenic patients have been constructed and validated. The Calgary Depression Scale (CDS) is a nine item scale, each item scored from 0 to 3. This scale was derived from the HDRS and the Present State Examination. Factor analysis showed that the CDS is unidimensional, has high internal consistency, and significant strong correlation with scores on the HDRS, Beck and BPRS depression scales. The CDS has been validated in different languages (Brazilian, Danish, French...). It has been shown that there is no overlap between negative or extrapyramidal and depressive symptoms assessed by the PDS in schizophrenic patients. The Psychotic Depression Scale (PDS) is a 32 item scale derived from the HDRS, PANSS, CPRS and AMDP, each item being rated from 0 to 7. A principal component analysis of the PDS items using a Varimax rotation disclosed 8 orthogonal components that account for 71% of the variance. These components involved the following dimensions : depressive mood, inhibition, vegetative signs, paranoid signs, strangeness of thought, inverse vegetative signs, guilt feelings and cognitive signs. The analysis revealed that the 'depressive mood' factor of the PDS was correlated with the 'depressive' factor and was slightly correlated with the cognitive factor of the PANSS. This first factor was not correlated with either the "negative" factor of the PANSS, or the Positive or Excitement factor of the PANSS. Hence, this PDS, factor distinguished depressive signs from negative symptoms. Due to their metrologic properties, specific scales should be preferred. However, only one open trial (of an antipsychotic) and two double blind controlled trials (one comparison of 2 antipsychotics and one comparison of an cholinesterase inhibitor versus placebo) have been published using the CDS. Likewise, only one double blind controlled trial using the PDS (comparison of 2 antipsychotics) has been published. No study of the effect of antidepressants in depressed schizophrenic patients has been published, using either the CDS or the PDS assessment criteria.

DISCUSSION

These specific scales are rarely used in clinical practice. Only about 1% of the US psychiatrists reported the use of the Calgary Depression Scale. Several open clinical trials have assessed the efficacy of antidepressant agents added to antipsychotic in patients with schizophrenia. They have produced inconsistent results but have suffered from methodological limits (short duration of the studies, non homogeneous inclusion criteria, heterogeneous assessment methods...). Due to the lack of a reference drug, double blind placebo-controlled trial are necessary. A recent meta-analysis has been performed on results of trials that have investigated the clinical efficacy of antidepressant medication (either tricyclics, SSRIs or others) in the treatment of depression in schizophrenic patients. In a subset of 5 trials (209 patients), the proportion improved in the antidepressant group was 26% (95% CI 10 to 42) higher than in the placebo group. The estimated number needed to treat was 4. In a subgroup of 6 studies (267 patients), the standardized mean difference on the HDRS score was -0.27 (95% CI - 0.7 to -0.2). There was no evidence that antidepressant treatment induced a deterioration of psychotic symptoms in these trials.

CONCLUSION

The results provide weak evidence for the efficacy of antidepressants in patients with schizophrenia and depression. Today, the only SSRI tested in the treatment of depression in schizophrenic patients is sertraline. One study led to positive results. Since the meta-analysis, one additional study has been performed comparing sertraline to placebo. No difference between the 2 treatment groups was demonstrated but the power of the trial was rather low. Further research is required to determine the best approach towards treating depression in patients with schizophrenia, with clinical trials performed for longer periods, using appropriate assessment criteria such as depressive symptoms and quality of life.

Long-term pharmacoclinical follow-up in schizophrenic patients treated with risperidone. Plasma and red blood cell concentrations of risperidone and its 9-hydroxymetabolite and their relationship to whole blood serotonin and tryptophan, plasma homovanillic acid, 5-hydroxyindoleacetic acid, dihydroxyphenylethyleneglycol and clinical evaluations

The aim of the study was to establish a relationship between the clinical efficacy of risperidone (Risp), the biological levels of Risp and its metabolite, 9-hydroxyrisperidone (9-OH-Risp), and the turnover of blood biogenic amines during a long-term treatment (1 year). Risp is one of the newer atypical antipsychotic drugs with potent serotonin (5HT2), moderate D2 and real alpha 1-alpha 2 adrenoreceptor antagonistic effects. The study has been performed in an open setting and included 17 patients, but only 15 were followed-up from 3 to 12 months. Pharmacokinetic analyses were conducted at the same time as clinical evaluations, grading using the Positive and Negative Syndrome Scale (PANSS), the Clinical Global Impressions (CGI), the Global Assessment of Functioning Scale (GAF), the Quality of Life Scale (QLS) and the Extrapyramidal Symptoms Rating Scale (ESRS) and the determinations of plasma and red blood cell (RBC) Risp and 9-OH-Risp, whole blood 5HT and tryptophan (Trp), plasma homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5HIAA) and dihydroxyphenylethyleneglycol (DHPG). The therapeutic drug monitoring needed oral Risp daily dose of 4.5 +/- 2.3 mg (range 2-8) and the stabilized concentrations (ng/ml) at endpoint in plasma and RBC were 10 +/- 8 (range 1-23) and 3.5 +/- 2 (range 1-8) for Risp and 29 +/- 19 (range 8-70) and 11.5 +/- 6.6 (range 2.6-22.5) for 9-OH-Risp, respectively. 9-OH-Risp appears to be the major active metabolite compound at higher concentrations than Risp. Positive linear correlations were found only between plasma and RBC 9-OH-Risp and the daily dose and the score of the GAF. Statistically significant clinical results showed that Risp is a potent antipsychotic agent efficacious both on positive and negative symptoms and on quality of life. Positive symptoms decreased after about the second month and the negative symptoms improved secondly. Patients (n = 8) who responded to Risp were characterized, on the long-term, by a statistically significant decrease of whole blood 5HT and increase of plasma DHPG.