Does eosinophilia predict clozapine induced neutropenia?

Haematological point of care testing for clozapine monitoring

BACKGROUND

Clozapine treatment requires regular full blood counts (FBC) because of the risk of agranulocytosis. Traditionally, FBCs use venous blood samples but the need for frequent venepuncture adversely affects adherence. We investigated the utility of a point of care testing (POCT) finger prick method for clozapine patients.

METHOD

Patients being treated with clozapine, who were having a venous blood sample taken for haematological monitoring, also provided a fingerprick capillary blood sample. The PixCell HemoScreen® POCT analyser was used to test both the capillary and venous samples, and the venous sample was also tested using a standard laboratory method.

RESULTS

We completed FBCs on 226 patients. We found strong correlations between the results from the standard laboratory venous method and the POCT capillary and venous assays for WBC (R = 0.96 & R = 0.99), neutrophils (R = 0.96 & R = 0.97) and eosinophils (R = 0.94 & R = 0.94). Compared with the standard laboratory venous blood method, mean biases for capillary blood POCT method were -0.56 × 10⁹/L for WBC, -0.39 × 10⁹/L for neutrophils, and -0.01 × 10⁹/L for eosinophils. Mean biases for venous blood POCT method were -0.004 × 10⁹/L for WBC, -0.28 × 10⁹/L for neutrophils, and 0.01 × 10⁹/L for eosinophils. Of the 226 patients tested, 10 (4.4%) had levels below clozapine monitoring thresholds (WBC <3.5 × 10⁹/L and Neutrophils <1.5 × 10⁹/L) by capillary blood, and 4 (1.8%) by venous blood by POCT. The standard laboratory method showed 3 of these to be sub-threshold. All cases of neutropenia were identified by capillary and venous POCT.

CONCLUSION

The PixCell HemoScreen® POCT analyser provided results that were comparable with those from a standard venous blood laboratory method for WBC, neutrophil and eosinophil counts. The availability of an accurate capillary monitoring method may result in increased clozapine uptake and better clozapine adherence.

Recognition and management of clozapine adverse effects: A systematic review and qualitative synthesis

OBJECTIVE

Clozapine is substantially underutilized in most countries and clinician factors including lack of knowledge and concerns about adverse drug effects (ADEs) contribute strongly to treatment reluctance. The aim of this systematic review was to provide clinicians with a comprehensive information source regarding clozapine ADEs.

METHODS

PubMed and Embase databases were searched for English language reviews concerned with clozapine ADEs; publications identified by the automated search were manually searched for additional relevant citations. Following exclusion of redundant and irrelevant reports, pertinent information was summarized in evidence tables corresponding to each of six major ADE domains; two authors reviewed all citations for each ADE domain and summarized their content by consensus in the corresponding evidence table. This study was conducted in accordance with PRISMA principles.

RESULTS

Primary and secondary searches identified a total of 305 unique reports, of which 152 were included in the qualitative synthesis. Most clozapine ADEs emerge within 3 months, and almost all appear within 6 months, after initiation. Notable exceptions are weight gain, diabetic ketoacidosis (DKA), severe clozapine-induced gastrointestinal hypomotility (CIGH), clozapine-induced cardiomyopathy (CICM), seizures, and clozapine-induced neutropenia (CIN). Most clozapine ADEs subside gradually or respond to dose reduction; those that prompt discontinuation generally do not preclude rechallenge. Rechallenge is generally inadvisable for clozapine-induced myocarditis (CIM), CICM, and clozapine-induced agranulocytosis (CIA). Clozapine plasma levels >600-1000 μg/L appear more likely to cause certain ADEs (e.g., seizures) and, although there is no clear toxicity threshold, risk/benefit ratios are generally unfavorable above 1000 μg/L.

CONCLUSION

Clozapine ADEs rarely require discontinuation.

Haematological side effects associated with clozapine: A retrospective study from India

OBJECTIVE

To evaluate the incidence of clozapine induced haematological side effects among patients receiving clozapine.

METHODS

Data of 333 patients who were on clozapine for a mean duration of 52.96 (45.18) months were reviewed for haematological abnormalities.

RESULTS

Most of the patients (n = 320; 96.1 %) were diagnosed with psychotic disorders, mainly schizophrenia. These patients were receiving clozapine in the dose range of 12.5 mg-600 mg/day, with a mean dose of 212.08 (102.43) mg/day at the time of review of their records. About one-tenth (N = 33; 9.9 %) of patients developed eosinophilia (absolute eosinophil count >600), and 8.2 % (N = 27) experienced thrombocytopenia (platelet count <100,000 cmm³) and 7 patients developed anaemia (haemoglobin level <10 gm%). Only 2 (0.6%) patients developed neutropenia. Mean dose (mg/day) at which haematological side-effects occurred were as follows: 159.85 (87.65) mg/day for eosinophilia; 193.98 (148.93) mg/day for thrombocytopenia; 78.57 (22.49) mg/day for anaemia. In a small proportion of patients, clozapine was discontinued due to the haematological abnormalities and in other patients these abnormalities normalized on its own in subsequent follow-up.

CONCLUSION

Clozapine is associated eosinophilia and thrombocytopenia, which are often benign and in majority of the patients these normalize with time.

Clozapine versus other antipsychotics during the first 18 weeks of treatment: A retrospective study on risk factor increase of blood dyscrasias

Blood dyscrasias excluding agranulocytosis received limited attention in antipsychotic-treated patients during the first 18 weeks of therapy, although severe clinical conditions have been reported in a few cases. We extracted data records of 285 Caucasian patients after 18 weeks of antipsychotic treatments to investigate risk factors of blood dyscrasias. We observed a higher risk to develop both transient and persistent anemia, neutrophilia and eosinophilia in clozapine-treated patients, whereas in those treated with other atypical antipsychotics when compared to a reference group under typical antipsychotics, emerged an increased risk for transient neutrophilia and eosinophilia. Male patients revealed a higher risk of persistent eosinophilia, neutrophilia, and leukocytosis. Concomitant treatments with mood stabilizers or benzodiazepines proved to be risk factors for transient anemia, antidepressants for transient eosinophilia. Severe complications emerged in 3 cases of agranulocytosis. Cross-tabulation analysis showed a higher probability of a poor response in clozapine-treated patients with persistent anemia and a positive with persistent neutrophilia and eosinophilia. Our data evidenced that emerging blood dyscrasias were not associated with critical adverse effects, and only agranulocytosis required a treatment interruption. Other atypical antipsychotics might represent a viable alternative to potentially harmful clozapine and typical antipsychotics at the onset of life-threatening haematological alterations.

Successful rechallenge with clozapine after treatment associated eosinophilia

OBJECTIVE

Eosinophilia has been associated with the use of clozapine. Where clozapine associated eosinophilia develops, and is associated with organ specific damage, clozapine is usually ceased. In cases of treatment associated eosinophilia without evidence of organ specific damage, clozapine would also typically be withdrawn. There are small numbers of reports in the literature describing patients who have had a successful rechallenge of clozapine having previously stopped treatment due to eosinophilia without associated organ specific inflammation. We report the case of a man who underwent a successful retrial of clozapine.

METHOD

Case from authors' clinical practice reviewed.

RESULTS

We present the case of a young man with treatment resistant schizophrenia who underwent a successful re-challenge of clozapine, having previously ceased treatment due to an eosinophilia associated with treatment.

CONCLUSION

We believe that the current report provides further evidence that it may be unnecessary to cease treatment in all patients who develop an eosinophilia without organ dysfunction whilst on clozapine. Furthermore, where clozapine has been ceased due to an eosinophilia without evidence of organ specific inflammation, clozapine rechallenge with increased haematological monitoring should be considered.

Late Onset Agranulocytosis with Clozapine Associated with HLA DR4 Responding to Treatment with Granulocyte Colony-stimulating Factor: A Case Report and Review of Literature

Agranulocytosis as a side effect of clozapine has been reported to be associated with initial phases of treatment, i.e., first six months. Agranulocytosis with clozapine during the initial phases of treatment has been linked to genetic vulnerability in the form of variations in the human leukocyte-antigen haplotypes. However, there is limited literature on late onset agranulocytosis with clozapine and this has very rarely been linked to human leukocyte-antigen haplotypes vulnerability. In this report we review the existing data on late onset agranulocytosis with clozapine and describe the case of a young man, who developed agranulocytosis with clozapine after 35 months of treatment and was found to have genetic vulnerability in form of being positive for HLA DR4. This case highlights underlying autoimmune immune mechanism in clozapine-induced agranulocytosis and the need for frequent blood count monitoring on clozapine even after the initial 6 months of starting treatment especially in patients with genetic vulnerability to develop this condition.

Eosinophilia induced by clozapine: a report of two cases and review of the literature

Clozapine, an atypical antipsychotic, has been used in the treatment of schizophrenia and other psychotic disorders. Although it has good therapeutic effect but many a time it use is overridden by the associated adverse effects which range from minor to severe life-threatening events. There has been extensive literature for severe side effects like leukocytosis but limited data are available for transient eosinophilia. Here, we present two cases of benign transient eosinophilia and discuss the importance of recognizing eosinophilia while using clozapine.

Immunomodulatory effects of clozapine and their clinical implications: what have we learned so far?

Clozapine remains the drug of choice for treatment resistant schizophrenia, but is associated with potentially life threatening side effects, including agranulocytosis and myocarditis. Immunological mechanisms may be involved in the development of these side effects or in the unique antipsychotic efficacy in subgroups of schizophrenia patients. This systematic review presents the immunomodulatory effects of clozapine from human in vitro and in vivo studies and relates these findings to the developments of adverse and therapeutic effects of clozapine. Several studies confirm the immunomodulatory actions of clozapine, but only few studies investigated their relationship to the unique adverse and therapeutic effects of clozapine. During the first month of clozapine treatment, up to 50% of patients develop fever and flu like symptoms, which is seemingly driven by increased cytokines. Within the same time period, the risk of side-effects with a suspected immunological mechanism peaks. Patients developing fever during the first weeks of treatment should have a thorough physical examination, and measurements of white blood cell count, absolute neutrophil count, ECG, C-reactive protein, creatinine kinase, and troponin to exclude infection, agranulocytosis, myocarditis and neuroleptic malignant syndrome. To what degree the unique antipsychotic efficacy of clozapine in subgroups of schizophrenia patients is related to its immunomodulatory effects has not been studied. Research relating the immunomodulatory actions of clozapine and its early markers to clinically relevant adverse and therapeutic outcomes is hoped to provide new leads for the understanding of the pathophysiology of schizophrenia and aid the development of novel treatment targets.

Clozapine induced eosinophilia

Clozapine is associated with a number of side effects and careful monitoring of them is a very important aspect of management of the patients receiving the same. Common side effects of clozapine are sedation, sialorrhoea, weight gain etc. Rarely clozapine is also associated with eosinophilia. Here we present a case of schizoaffective disorder who was receiving clozapine and developed eosinophilia during the initial weeks of treatment with clozapine which came down to baseline after a few weeks of continuation of therapy. Although there are reports of eosinophilia developing in course of treatment with clozapine among patients suffering from schizophrenia but this may be the first case of eosinophilia associated with clozapine use in case of schizoaffective disorder.

Morning pseudoneutropenia during clozapine treatment

Clozapine, an atypical antipsychotic drug, is associated with a high risk of neutropenia and agranulocytosis, necessitating the immediate discontinuation of the drug. We report the case of a patient who developed clozapine-induced neutropenia. Assessments revealed a pronounced diurnal variation in the number of circulating neutrophils (1200-1900/mm(3) in the morning and 2200-2700/mm(3) in the afternoon). Due to these circadian changes, we decided to continue clozapine treatment.

Clozapine versus typical neuroleptic medication for schizophrenia

BACKGROUND

Long-term drug treatment of schizophrenia with typical antipsychotics has limitations: 25 to 33% of patients have illnesses that are treatment-resistant. Clozapine is an antipsychotic drug, which is claimed to have superior efficacy and to cause fewer motor adverse effects than typical drugs for people with treatment-resistant illnesses. Clozapine carries a significant risk of serious blood disorders, which necessitates mandatory weekly blood monitoring at least during the first months of treatment.

OBJECTIVES

To evaluate the effects of clozapine compared with typical antipsychotic drugs in people with schizophrenia.

SEARCH STRATEGY

For the current update of this review (March 2006) we searched the Cochrane Schizophrenia Group Trials Register.

SELECTION CRITERIA

All relevant randomised clinical trials (RCTs).

DATA COLLECTION AND ANALYSIS

We extracted data independently. For dichotomous data we calculated relative risks (RR) and their 95% confidence intervals (CI) on an intention-to-treat basis, based on a fixed-effect model. We calculated numbers needed to treat/harm (NNT/NNH) where appropriate. For continuous data, we calculated weighted mean differences (WMD) again based on a fixed-effect model.

MAIN RESULTS

We have included 42 trials (3950 participants) in this review. Twenty-eight of the included studies are less than 13 weeks in duration, and, overall, trials were at significant risk of bias. We found no significant difference in the effects of clozapine and typical neuroleptic drugs for broad outcomes such as mortality, ability to work or suitability for discharge at the end of the study. Clinical improvements were seen more frequently in those taking clozapine (n=1119, 14 RCTs, RR 0.72 CI 0.7 to 0.8, NNT 6 CI 5 to 8). Also, participants given clozapine had fewer relapses than those on typical antipsychotic drugs (n=1303, RR 0.62 CI 0.5 to 0.8, NNT 21 CI 15 to 49). BPRS scores showed a greater reduction of symptoms in clozapine-treated patients, (n=1145, 16 RCTs, WMD -4.22 CI -5.4 to -3.1), although the data were heterogeneous (Chi(2) 0.0001, I(2) 66%). Short-term data from the SANS negative symptom scores favoured clozapine (n=196, 5 RCTs, WMD -5.92 CI -7.8 to -4.1). We found clozapine to be more acceptable in long-term treatment than conventional antipsychotic drugs (n=982, 16 RCTs, RR 0.60 CI 0.5 to 0.7, NNT 15 CI 12 to 20). Blood problems occurred more frequently in participants receiving clozapine (3.2%) compared with those given typical antipsychotics (0%) (n=1031, 13 RCTs, RR 7.09 CI 2.0 to 25.6). Clozapine participants experienced more drowsiness, hypersalivation, or temperature increase, than those given conventional neuroleptics. However, clozapine patients experienced fewer motor adverse effects (n=1433, 18 RCTs, RR 0.58 CI 0.5 to 0.7, NNT 5 CI 4 to 6).The clinical effects of clozapine were more pronounced in participants resistant to typical neuroleptics in terms of clinical improvement (n=370, 4 RCTs, RR 0.71 CI 0.6 to 0.8, NNT 4 CI 3 to 6) and symptom reduction. Thirty-four per cent of treatment-resistant participants had a clinical improvement with clozapine treatment.

AUTHORS' CONCLUSIONS

Clozapine may be more effective in reducing symptoms of schizophrenia, producing clinically meaningful improvements and postponing relapse, than typical antipsychotic drugs - but data are weak and prone to bias. Participants were more satisfied with clozapine treatment than with typical neuroleptic treatment. The clinical effect of clozapine, however, is, at least in the short term, not reflected in measures of global functioning such as ability to leave the hospital and maintain an occupation. The short-term benefits of clozapine have to be weighed against the risk of adverse effects. Within the context of trials, the potentially dangerous white blood cell decline seems to be more frequent in children and adolescents and in the elderly than in young adults or people of middle-age.The existing trials have largely neglected to assess the views of participants and their families on clozapine. More community-based long-term randomised trials are needed to evaluate the efficacy of clozapine on global and social functioning as trials in special groups such as people with learning disabilities.

A review of clozapine safety

Clozapine is a distinctive antipsychotic agent, having a unique clinical profile and an idiosyncratic safety profile. More so than with other agents, the weighting of its adverse event profile is critical, in order to counterbalance its clear clinical advantages. The safety issues with clozapine are in a number of areas, some of which are considered medical emergencies and potentially life-threatening. These include haematological (neutropenia and agranulocytosis), CNS (seizures), cardiovascular (myocarditis and cardiomyopathy), metabolic (diabetes), gastrointestinal and neuromuscular. Understanding the safety profile of clozapine allows an informed use of the agent that can maximise its clear clinical benefit and minimise the known risks.

Simultaneous determination of clozapine and its N-desmethyl and N-oxide metabolites in plasma by liquid chromatography/electrospray tandem mass spectrometry and its application to plasma level monitoring in schizophrenic patients

A liquid chromatography tandem mass spectrometry (LC-MS-MS) assay method for the simultaneous determination of clozapine and its N-desmethyl (norclozapine) and N-oxide metabolites in human plasma is described. The compounds were extracted from plasma by a single step liquid-liquid extraction procedure and analyzed using a high performance liquid chromatography electrospray tandem mass spectrometer system. The compounds were eluted isocratically on a C-18 column, ionized using positive ion atmospheric pressure electrospray ionization method by a TurboIonspray source and analyzed using multiple reaction monitoring mode. The ion transitions monitored were m/z 327 --> m/z 270 for clozapine, m/z 313 --> m/z 192 for norclozapine, m/z 343 --> m/z 256 for clozapine-N-oxide and m/z 421--> m/z 201 for internal standard. The standard curves of clozapine, norclozapine and clozapine-N-oxide were linear over the range of 1 ng/ml to 1000 ng/ml when 0.5 ml of plasma was used for the analysis (r(2) >0.998). Three pooled plasma samples collected from patients who were treated with clozapine were used as long-term quality control samples to check the validity of spiked standard curve samples made at various times. The intra- and inter-assay variations for the spiked standard curve and quality control samples were less than 14%. These variations for the long-term patient quality control samples were less than 11%. The LC-MS-MS assay for simultaneous determination of clozapine, norclozapine and clozapine-N-oxide reported here is highly specific, sensitive, accurate and rapid. This method is currently being used for the plasma level monitoring of clozapine and its N-desmethyl and N-oxide metabolites in patients treated with clozapine. The plasma levels of clozapine, norclozapine and clozapine-N-oxide varied widely within and among patients. The data revealed that the norclozapine and clozapine N-oxide metabolites were present at about 58%+/-14% and 17%+/-6% of clozapine concentrations in plasma, respectively.

A second trial of clozapine in a case of granulocytopenia

It is generally believed that agranulocytosis, a major problem with clozapine treatment, will tend to occur dose-dependently once it develops in an individual. Therefore, despite clinical progress obtained, the drug has to be discontinued and treatment shifts to another drug. We report on the case of a 29-year-old woman with DSM-IV undifferentiated schizophrenia who developed agranulocytosis after 5 years of 300 mg/day clozapine treatment. The drug was withdrawn and two trials with thioridazine and olanzapine were unsuccessful. Four months after clozapine suspension, we decided to make a further trial, reintroducing clozapine titrated up to 500 mg/day. The patient's symptoms improved and blood leukocytes remained within the normal range after eight months. Copyright 2000 John Wiley & Sons, Ltd.

Zuclopenthixol-associated neutropenia and thrombocytopenia

OBJECTIVE

To report a case of neutropenia and thrombocytopenia secondary to use of zuclopenthixol in a schizophrenic patient.

CASE SUMMARY

A 66-year-old white man with chronic schizophrenia was referred to the hospital due to neutropenia and thrombocytopenia that developed shortly after initiation of zuclopenthixol therapy. Prior to zuclopenthixol administration, his white blood cell and platelet counts were 8.5 x 10(9) cells/L3 and 305 cells x 10(9)/L, respectively. Progressive reduction in leukocyte and platelet counts occurred, reaching a nadir of 2.9 x 10(9) cells/L3 (granulocytes 18.9%) and 109 cells x 10(9)/L, respectively. Zuclopenthixol was discontinued on admission, resulting in complete recovery within the next five days.

DISCUSSION

Neutropenia and thrombocytopenia are well-known complications of antipsychotic drug therapy. Zuclopenthixol, a well-established antipsychotic agent, has relatively few adverse effects. The rapid decrease of white blood cell and platelet counts following the initiation of zuclopenthixol, as well as the rapid recovery, implicate zuclopenthixol as the predominant cause for neutropenia and thrombocytopenia in this patient.

CONCLUSIONS

Although neutropenia and thrombocytopenia are rare complications of zuclopenthixol therapy, monitoring blood counts in patients receiving this agent seems to be justified.

Eosinophilia after commencement of clozapine treatment

OBJECTIVE

While clozapine-associated agranulocytosis has received extensive attention, a number of recent publications have identified that the incidence of eosinophilia may also be of concern. This retrospective review identifies the incidence of eosinophilia within a group of people commencing clozapine at a large hospital in Australia.

METHOD

The pathology reports of all people (n = 160) who commenced clozapine within a 3.5-year period were retrospectively reviewed for incidences of eosinophilia.

RESULTS

The incidence of eosinophilia was identified as 13%, comprising 17 males and four females. All cases of eosinophilia developed within 4 weeks of commencing clozapine. One male reached a peak eosinophil level of 9 x 10(9)/L, which resolved after clozapine was withdrawn. In all other cases, the eosinophilia resolved without intervention.

CONCLUSIONS

With a rate of eosinophilia at 13% in this population under review, and given that there have been reports of 25 cases of eosinophilic cardiomyopathy resulting in four deaths worldwide, clinicians should be alert to the incidence and sequelae of eosinophilia in people receiving clozapine treatment.

Hepatotoxicity of clozapine

Two hundred thirty-eight patients treated with either haloperidol or clozapine were investigated to shed more light on the incidence and severity of antipsychotic-induced liver enzyme increase. Serum glutamic-pyruvic transaminase (SGPT) increase was most frequently seen in both treatment groups. When analyzing the incidence rates for patients with increased liver enzyme values (serum glutamic-oxaloacetic transaminase, SGPT, gamma-glutamyl transpeptidase) that were higher than twice the upper limit of the normal range, clozapine-treated patients showed an SGPT increase (37.3%) significantly more frequently than patients treated with haloperidol (16.6%). Both patients with higher clozapine plasma levels and male patients were at a higher risk for an SGPT increase. At least 60% of the increase of the different enzymes remitted within the first 13 weeks of treatment. In general, the authors conclude that clozapine-induced liver enzyme elevation seems to be a common and mostly transient phenomenon.