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Br J Clin Pharmacol. 2007 Jul;64(1):49-56. Epub 2007 Feb 12.

Gender, age, smoking behaviour and plasma clozapine concentrations in 193 Chinese inpatients with schizophrenia.

Author information

1
Beijing Anding Hospital, Capital University of Medical Sciences, Beijing, China. ytang@genetics.emory.edu

Abstract

AIM:

To study the relationship between age, gender, cigarette smoking and plasma concentrations of clozapine (CLZ) and its metabolite, norclozapine (NCLZ) in Chinese patients with schizophrenia.

METHODS:

Data from a therapeutic drug monitoring programme were analysed retrospectively. One hundred and ninety-three Chinese inpatients with schizophrenia were assessed using clinical data forms. Steady-state plasma concentrations of CLZ and NCLZ were assayed using high-performance liquid chromatography. Comparisons of dosage and plasma CLZ concentrations were undertaken between males (n = 116) and females (n = 77), younger (<or=40 years, n = 82) and older patients (>40 years, n = 111) and current male smokers (n = 50) and nonsmokers (n = 66).

RESULTS:

(i) Plasma CLZ concentrations demonstrated large interindividual variability, up to eightfold at a given dose; (ii) there were significant effects of gender on plasma CLZ concentrations (relative to dose per kg of body weight) with female patients having significantly higher concentrations than males (30.09 +/- 24.86 vs. 19.87 +/- 3.55 ng ml(-1) mg(-1) day(-1) kg(-1); P < 0.001); (iii) there were no significant differences in plasma CLZ concentrations between those patients <or=40 years old and those >40 years; and (iv) there were no significant differences in plasma CLZ concentrations between male smokers and nonsmokers, despite the CLZ dosage for smokers being significantly higher.

CONCLUSIONS:

Plasma CLZ concentrations vary up to eightfold in Chinese patients. Among the patient-related factors investigated, only gender was significant in affecting CLZ concentrations in Chinese patients with schizophrenia, with female patients having higher levels.

PMID:
17298477
PMCID:
PMC2000616
DOI:
10.1111/j.1365-2125.2007.02852.x
[Indexed for MEDLINE]
Free PMC Article

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