Evidence map›Paper›PMID 41356387›Full record

ArticleBiomedical reports2026

Clozapine (and norclozapine) concentrations are correlated with functioning, disability and side-effects when patients are treated with clozapine without the availability of therapeutic drug monitoring: A study of treatment-resistant schizophrenia inpatients.

Veroljub Petrovic, Dan Cohen, Dragic Bankovic, Branimir Radmanovic, Dragana Ignjatovic Ristic

Abstract read
In one paragraph

Article in Biomedical reports, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.

0numbers the graph read from it
0cells of the map it votes in
1citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

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Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

1 citing paper in PubMed.

  1. Article
4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

5 authors.

Veroljub PetrovicSpecial Hospital for Psychiatric Disorders Kovin, 26220 Kovin, Serbia.
Dan CohenEsdege Reigersdaal. J. Oudweg 2, 1703 DE Heerhugowaard, The Netherlands.
Dragic BankovicFaculty of Science, University of Kragujevac, 34000 Kragujevac, Serbia.
Branimir RadmanovicFaculty of Medical Sciences University of Kragujevac, 34000 Kragujevac, Serbia.
Dragana Ignjatovic RisticFaculty of Medical Sciences University of Kragujevac, 34000 Kragujevac, Serbia.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

In numerous countries, including Serbia, therapeutic drug monitoring (TDM) for clozapine is unavailable, leaving dose adjustments based solely on clinical judgment, could increase risk of therapeutic failure or adverse outcomes. The present study aimed to assess associations between clozapine and norclozapine serum concentrations, measured via Dried Blood Spot (DBS), and symptom severity, functioning, disability, and side effects in Serbian inpatients with treatment-resistant schizophrenia (TRS). In a cross-sectional design, patients with TRS with ongoing clozapine treatment and who did not meet exclusion criteria, were to be included. For clinical assessments of symptom severity, functionality, disability and side effects, were used: Simplified Interview for Negative and Positive Symptoms (SNAPSI), Clinical Global Impression (CGI), Global Assessment of Functioning (GAF), WHO Disability Assessment Schedule (WHODAS) and the Clozapine Adverse Effects Scale (GASS-C). Spearman's analysis showed no significant correlation between GASS-C scores and clozapine dose or plasma levels. WHODAS scores showed significant positive correlations with clozapine dose (ρ=0.409, P=0.006), clozapine (ρ=0.333, P=0.038) and norclozapine (ρ=0.481, P=0.002) levels. GAF scores negatively correlated with clozapine (ρ=-0.354, P=0.027) and norclozapine (ρ=-0.370, P=0.020). GASS-C scores were significantly associated with female sex (P=0.003), body mass index (BMI; ρ=-0.678, P<0.0005) and WHODAS scores (ρ=0.372, P=0.014). Regression analysis identified clozapine dose, clozapine level, BMI, SNAPSI and CGI scores as significantly associated with GASS-C (P=0.045). Norclozapine, BMI and CGI scores significantly associated with WHODAS (P=0.018). In the present study, it was found that clozapine and norclozapine concentrations are significantly associated with functioning, disability and side effects in patients with TRS treated without TDM. DBS-based monitoring may offer a valuable alternative for optimizing treatment. Further longitudinal studies are needed to clarify the clinical utility of (nor) clozapine level-guided care in such settings.

Indexed as

clozapinedisability levelsdried blood stainsside effectstreatment-resistant schizophrenia

Identifiers

PMID41356387
PMCPMC12679552

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