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

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.

• Authors: Yi-lang Tang, Peixian Mao, Feng-Min Li, Wenbiao Li, Qi Chen, Feng Jiang, Zhuo-ji Cai, Philip B Mitchell
• Journal: British journal of clinical pharmacology (Br J Clin Pharmacol) Vol. 64 Issue 1 Pg. 49-56 (Jul 2007) ISSN: 0306-5251 [Print] England
• PMID: 17298477 (Publication Type: Journal Article)

Chemical References

• Antipsychotic Agents
• norclozapine
• Clozapine

Topics

• Adult
• Age Factors
• Aged
• Aged, 80 and over
• Antipsychotic Agents (blood, therapeutic use)
• Asian People
• Clozapine (analogs & derivatives, blood, therapeutic use)
• Dose-Response Relationship, Drug
• Female
• Humans
• Male
• Middle Aged
• Retrospective Studies
• Schizophrenia (blood, drug therapy)
• Sex Factors
• Smoking (metabolism)