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Purpose/background: Neuroleptic malignant syndrome (NMS) has been described with most antipsychotics, most commonly first generation. Clozapine has also been associated with NMS., Methods/procedures: We conducted a systematic review to identify all studies investigating or describing (a) clozapine rechallenge following suspected NMS associated with clozapine, (b) clozapine use after suspected NMS associated with another antipsychotic, and (c) rechallenge with nonclozapine antipsychotics after suspected clozapine-associated NMS., Findings/results: We identified 51 reports detailing 67 cases. Thirty-eight described clozapine administration after NMS on a nonclozapine antipsychotic; 12 described a clozapine rechallenge after an NMS on clozapine monotherapy; and 17 described the use of nonclozapine antipsychotics after an NMS on clozapine. The outcome of clozapine rechallenge was favorable (no recurrence of NMS) in 92% (n = 11) of cases after an NMS on clozapine and in 79% (n = 30) of those prescribed clozapine following NMS on a nonclozapine antipsychotic. Most (82%; n = 14) cases after NMS on clozapine had no recurrence of NMS on receiving a nonclozapine antipsychotic.No mortality was reported with any of these interventions., Implications/conclusions: Our findings suggest that rechallenge following clozapine NMS is possible, and with careful risk-benefit analysis consideration, a clozapine rechallenge can be made. A publication bias in favor of cases in which rechallenge was successful is probable and is an important limitation.

Purpose/background: Clozapine is the criterion standard in treatment-resistant schizophrenia. We sought to review data on several inflammatory effects associated with clozapine, specifically interstitial nephritis, hepatitis, and pancreatitis., Methods/procedures: We conducted a systematic review to identify studies, published up until December 2017, describing clozapine-induced hepatitis, nephritis, and pancreatitis. The primary objective was to characterize the clinical characteristics associated with each of the specific inflammatory reactions to clozapine., Findings/results: We identified 42 cases of inflammatory reactions associated with clozapine treatment- 20 :cases of clozapine-induced hepatitis, 11 cases of nephritis, and 11 of pancreatitis. The mean (SD) age was 38.8 (11.9) years. The mean (SD) dose of clozapine used was 252.4 (133.7) mg. Time to onset of pancreatitis (17.9 [11.2] days; range 4-35 days) was shorter than that for hepatitis (34.2 [20.1] days; range, 12-90 days) and nephritis (27.9 [27.0]; range, 8-90 days) but was not statistically significant (F = 2.267, P = 0.117). The mean (SD) time to recovery was shorter for cases of pancreatitis (15.7 [18.4] days) compared with cases of hepatitis (25.9 [16.5] days) and nephritis (24.5 [18.9] days). Three cases with hepatitis died. Seven of the cases had a clozapine rechallenge (hepatitis [n = 3], nephritis [n = 1], pancreatitis [n = 3]), with 5 having a recurrence at a mean (SD) onset of 3.5 (2.5) days (range, 1-7 days); 2 hepatitis cases were successfully rechallenged., Implications/conclusions: Clozapine-induced hepatitis, nephritis, and pancreatitis are uncommon adverse events, reflected in the paucity of case studies in the literature. Early recognition of the signs and symptoms of clozapine-associated hepatitis, nephritis, and pancreatitis is important, as when identified, clozapine should be urgently discontinued. Clozapine is associated with evidence of benign inflammatory processes; the extent to which hepatitis, and other inflammatory reactions, may be on a continuum with these more benign and self-limiting reactions is unclear, and this can only be resolved by prospectively following cohorts of clozapine-treated patients.

Purpose/background: Clozapine is associated with hematological abnormalities, with neutropenia and agranulocytosis of most concern. Granulocyte colony-stimulating factor (G-CSF) has been used to support clozapine rechallenge after neutropenia with the aim of maintaining the neutrophil count. This study aims to explore the practice, use, safety, and efficacy of G-CSF in this context., Methods/procedures: We conducted a systematic review to identify all studies investigating or describing G-CSF as a prophylaxis to enable continued clozapine treatment during a rechallenge., Findings/results: We identified 32 reports of patients who received G-CSF either regularly (n = 23) or as required (n = 9) to support clozapine rechallenge after an episode of neutropenia necessitating discontinuation of clozapine. Seventy-five percent (n = 24) of published cases remained on clozapine with the use of continual prophylactic G-CSF or after single G-CSF administrations (n = 8). Seventy percent (n = 16) of patients in receipt of continual prophylactic G-CSF were successfully maintained on clozapine. However, 1 of the 3 episodes of rechallenge in those with a history of severe agranulocytosis (absolute neutrophil count <0.1 × 10/L) had a recurrence of agranulocytosis at week 9., Implications/conclusions: Our findings suggest that G-CSF can sometimes be safely used to support the maintenance of normal neutrophil counts and clozapine use after neutropenia. Publication bias is an important limitation, however. Also, few reports clearly documented the presence or absence of an independent nonclozapine cause of the index neutropenia, which may have increased success rates. Furthermore, adverse events were not systematically recorded. Prospective studies are needed to determine safety because if agranulocytosis occurs on clozapine while supported by G-CSF, there is no obvious alternate rescue therapy to promote granulopoiesis. From the available data, it is not possible to recommend this course of action for someone with a true clozapine agranulocytosis.

Purpose/background: Clozapine is associated with hematological abnormalities, notably neutropenia, which may progress to agranulocytosis. Granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) have been used to reduce the frequency and duration of clozapine-associated neutropenia. This review aims to explore the use, efficacy, and tolerability of these cytokines in the treatment of clozapine-associated agranulocytosis., Methods/procedures: We conducted a systematic review of published interventional and observational studies, case series, and case reports where G-CSF/GM-CSF was used to treat clozapine-associated agranulocytosis., Findings/results: We identified 29 reports (40 patients). The median duration of neutrophil recovery time after stopping clozapine and starting cytokine treatment was 7 days (range, 2-13 days) for those with agranulocytosis (absolute neutrophil count < 0.5 × 10 cells/L). Ninety-four percent (n = 29) had no serious adverse reactions, and no deaths occurred., Implications/conclusions: Our findings indicate that G-CSF/GM-CSF use is well tolerated and suggest that G-CSF can sometimes be safely used to reduce the duration of neutropenia associated with clozapine use. However, the interpretation of this outcome is difficult, given the likely publication bias for positive outcomes in case reports.

Background: Clozapine remains the only evidence-based treatment for treatment-resistant schizophrenia, and prediction of clozapine response is important in developing stratified treatment. We studied potential predictors of clozapine response, applying functional assessments as well as service use., Procedures: We performed a nationwide cohort study among all individuals diagnosed with schizophrenia in Denmark after 1995 (age, ≥18 years) who initiated clozapine treatment between 2004 and 2011 with a Global Assessment of Functioning (GAF-F) score registered at clozapine initiation. During up to 2-year follow-up, clinical response was defined as (a) no further hospitalization with schizophrenia or (b) improvement in GAF-F score (moderate improvement: increase, ≥10; substantial improvement: increase, ≥20; and GAF-F, ≥50). We performed Cox regression analysis and report adjusted hazard rate ratios (HRRs; 95% confidence intervals [95% CIs])., Results: Among 502 clozapine users with a registered GAF-F score, 232 (46.2%) remained out of hospital, 96 (19.1%) achieved moderate functional improvement, and 29 (5.8%) substantial functional improvement. Of all potential predictors, voluntary status at clozapine initiation showed borderline statistical significance with nonhospitalization (HRR, 1.61; 95% CI, 0.97-2.67). Regarding functional improvement, living with a partner was the strongest predictor with an almost threefold increased HRR (2.78; 95% CI, 1.07-7.23). Female sex was only nonsignificantly associated with functional improvement, whereas the chance of substantial improvement decreased by 15% (HRR, 0.85; 95% CI, 0.72-1.00) for each year delay in clozapine initiation among females., Conclusions: Living with a partner was the strongest predictor of functioning after clozapine initiation in this study. Although potentially indicating better premorbid functioning, this finding stresses the need and importance of social support during the course of the treatment independent of clinical factors.