P.3.e.004 Pharmacokinetics of quetiapine: evidence from a routine therapeutic drug monitoring service

Castberg, Ingrid; Skogvoll, Eirik; Spigset, Olav

doi:10.1016/s0924-977x(06)70574-0

Cited by 31 publications

(59 citation statements)

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“…The range of plasma quetiapine concentrations measured in the present study are broadly comparable with those reported by others: median (range) 101 (<4-1816) μg/l [Castberg et al 2007] and 103 (7-1190) μg/l [Bakken et al 2011], although the highest concentrations measured here were above these ranges for all doses above 400 mg/day. By way of comparison, of 14 patients presenting after quetiapine self-poisoning (suspected ingested dose range 1.2-18 g), serum quetiapine concentrations were in the range 1100-8800 µg/l (time between ingestion and sampling 1-26 h) [Hunfeld et al 2006].…”

Section: Plasma Quetiapine and Dosesupporting

confidence: 91%

Plasma quetiapine in relation to prescribed dose and other factors: data from a therapeutic drug monitoring service, 2000–2011

Handley

Bowskill

Patel

et al. 2012

Therapeutic Advances in Psychopharmacology

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Objective: Suggested predose plasma quetiapine target ranges for effective therapy in schizophrenia lie between 50 and 500 µg/l. We aimed to examine data from a quetiapine therapeutic drug monitoring (TDM) service to assess the plasma quetiapine concentrations attained at specified doses in clinical practice. Method: We studied TDM data from patients given immediate-release quetiapine in the period 2000-2011.Results: There were 946 samples from 487 patients (257 males, age at time of first sample, median [range] 34 [14-87] years, and 230 females, age at time of first sample, median [range] 38 [10-92] years). The plasma quetiapine concentration was <50 and <100 µg/l in 30% and 50% of samples, respectively (no quetiapine detected in 9% of samples). The relationship between dose and plasma quetiapine was poor. The mean (95% confidence interval [CI]) quetiapine dose was higher (t = 3.6, df = 446, p <0.01) in males versus females (641 and 548 [600-943] mg/day, respectively), although there was no difference in median dose (600 mg/ day) or in the mean (95% CI) plasma quetiapine concentrations attained. Smoking habit had no discernible effect on plasma quetiapine concentration. Conclusions: There was a poor relationship between dose and plasma quetiapine concentration in this study, as found by others. This is probably because of the short plasma half-life of the drug, at least in part. Nevertheless, quetiapine TDM can help assess adherence and measurement of quetiapine metabolites, notably N-desalkylquetiapine, as well as quetiapine itself may enhance the value of quetiapine TDM in future.

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Section: Plasma Quetiapine and Dosesupporting

confidence: 91%

Plasma quetiapine in relation to prescribed dose and other factors: data from a therapeutic drug monitoring service, 2000–2011

Handley

Bowskill

Patel

et al. 2012

Therapeutic Advances in Psychopharmacology

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“…The other drugs were analyzed by LC-MS after liquid-liquid extraction using mixtures of hexane, acetonitrile, and/or butanol, or dichloromethane and isopropanol. [24][25][26][27] Thereafter, the analytes were separated on C18 columns using methanol, acetonitrile, formic acid, or ammonium acetate as mobile phases and quantified on Agilent MSD 1100 LC-MS systems (Agilent Technologies, Palo Alto, CA). Together with unknown patient samples, each analytical series contained 7 calibrators covering therapeutic, subtherapeutic, and toxic concentrations.…”

Section: Methodsmentioning

confidence: 99%

Prescribing Patterns and the Use of Therapeutic Drug Monitoring of Psychotropic Medication in a Psychiatric High-Security Unit

Castberg¹,

Spigset²

2008

Therapeutic Drug Monitoring

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The aim of this study was to investigate the use of psychotropic medication and therapeutic drug monitoring in a high-security psychiatric unit and to compare the doses and serum concentrations both with the recommended intervals and with the doses and serum concentrations in a control group. One hundred thirty-two patients were admitted in the period from January 2000 to December 2005. All available samples were used when comparing serum concentrations and doses with the recommended ranges. For the comparison of doses and serum concentration-to-dose (C:D) ratios with the control group only 1 sample from each patient was used. A total of 459 analyses of 27 different drugs in samples from 8 women and 73 men were included. The median number of therapeutic drug monitoring analyses per patient was 4 (range 1-29). Thirty-seven of the 81 patients (46%) used 2 or more antipsychotics at the same time. Clozapine, lamotrigine, olanzapine, quetiapine, ziprasidone, and zuclopenthixol were often given in doses above the recommended. The serum levels were frequently above those recommended for clozapine, olanzapine, quetiapine, risperidone, ziprasidone, and zuclopenthixol. The serum levels were significantly higher in the study group than in the control group for clozapine, lamotrigine, quetiapine, and zuclopenthixol. The given dose was significantly higher in the study group than in the control group for clozapine, lamotrigine and zuclopenthixol. The C:D ratio was significantly lower in the study group than in the control group for olanzapine but higher for quetiapine. The non-evidence based practice of high-dose polypharmacy with several antipsychotics is widely used in this unit. The use of higher doses in the study group than in the control group was not due to differences in metabolism or adherence to treatment between the 2 groups. The frequent use of therapeutic drug monitoring did not seem to have a great impact on the prescribed doses.

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“…7 The above case is reported not only for the unusual PGx but also because it accompanied drugdrug interactions. CLO and QUE co-administration would increase quetiapine level 8 and should be avoided especially for PKG86. Despite the current gap between research studies and the practical tools available to the clinician, it is hoped that in the foreseeable future, PGx will become a critical aid to guide the development of personalized therapeutic regimes with fewer adverse effects.…”

Section: Discussionmentioning

confidence: 99%

A Case of a Schizophrenic Patient with Unusual Pharmacogenetics Profile

Miroshnichenko¹,

Baymeeva²,

Иванова

et al. 2017

PPIJ

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There are plenty of evidences supporting the contribution of genetic variability to the mechanisms that responsible for both therapeutic and adverse effects of antipsychotic medications. We report a case that is an example of using cytochrome P450 pharmacogenetics and therapeutic drug monitoring in an attempt to guide schizophrenia treatment. This example illustrates the potential of applying the principles of predictive, preventive, and personalized medicine to the therapy of psychotic disorders.

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P.3.e.004 Pharmacokinetics of quetiapine: evidence from a routine therapeutic drug monitoring service

Cited by 31 publications

References 0 publications

Plasma quetiapine in relation to prescribed dose and other factors: data from a therapeutic drug monitoring service, 2000–2011

Plasma quetiapine in relation to prescribed dose and other factors: data from a therapeutic drug monitoring service, 2000–2011

Prescribing Patterns and the Use of Therapeutic Drug Monitoring of Psychotropic Medication in a Psychiatric High-Security Unit

A Case of a Schizophrenic Patient with Unusual Pharmacogenetics Profile

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