Research
Print page Print page
Switch language
The Capital Region of Denmark - a part of Copenhagen University Hospital
Published

The significance of sampling time in therapeutic drug monitoring of clozapine

Research output: Contribution to journalJournal articleResearchpeer-review

DOI

  1. Trajectory of cognitive functions in bipolar disorder: for better or worse?

    Research output: Contribution to journalJournal articleResearchpeer-review

  2. Incidence of suicidal behaviour and violent crime following antidepressant medication: a Danish cohort study

    Research output: Contribution to journalJournal articleResearchpeer-review

  3. Response to comment on Osler et al: misinterpretation of pre- and post differences invalidate the authors' conclusion

    Research output: Contribution to journalComment/debateResearchpeer-review

  4. Societal costs of Borderline Personality Disorders: a matched-controlled nationwide study of patients and spouses

    Research output: Contribution to journalJournal articleResearchpeer-review

  5. Meta-analysis of antidepressant effects of anti-inflammatory drugs-reply

    Research output: Contribution to journalComment/debateResearchpeer-review

View graph of relations

OBJECTIVE: Therapeutic drug monitoring (TDM) of clozapine is standardized to 12-h postdose samplings. In clinical settings, sampling time often deviates from this time point, although the importance of the deviation is unknown. To this end, serum concentrations (s-) of clozapine and its metabolite N-desmethyl-clozapine (norclozapine) were measured at 12 ± 1 and 2 h postdose.

METHOD: Forty-six patients with a diagnosis of schizophrenia, and on stable clozapine treatment, were enrolled for hourly, venous blood sampling at 10-14 h postdose.

RESULTS: Minor changes in median percentage values were observed for both s-clozapine (-8.4%) and s-norclozapine (+1.2%) across the 4-h time span. Maximum individual differences were 42.8% for s-clozapine and 38.4% for s-norclozapine. Compared to 12-h values, maximum median differences were 8.4% for s-clozapine and 7.3% for s-norclozapine at deviations of ±2 h. Maximum individual differences were 52.6% for s-clozapine and 105.0% for s-norclozapine. The magnitude of s-clozapine differences was significantly associated with age, body mass index and the presence of chronic basophilia or monocytosis.

CONCLUSION: The impact of deviations in clozapine TDM sampling time, within the time span of 10-14 h postdose, seems of minor importance when looking at median percentage differences. However, substantial individual differences were observed, which implies a need to adhere to a fixed sampling time.

Original languageEnglish
JournalActa Psychiatrica Scandinavica
Volume135
Issue number2
Pages (from-to)159-169
Number of pages11
ISSN0001-690X
DOIs
Publication statusPublished - Feb 2017

    Research areas

  • Adult, Antipsychotic Agents, Clozapine, Dose-Response Relationship, Drug, Drug Administration Schedule, Drug Monitoring, Female, Humans, Male, Middle Aged, Schizophrenia, Young Adult, Clinical Trial, Journal Article

ID: 52615546