Plasma, Oral Fluid, and Whole-Blood Distribution of Antipsychotics and Metabolites in Clinical Samples

Point of care assay for blood aripiprazole concentrations: development, validation and utility

BACKGROUND

The antipsychotic aripiprazole is often used in the treatment of first-episode psychosis. Measuring aripiprazole blood levels provides an objective measure of treatment adherence, but this currently involves taking a venous blood sample and sending to a laboratory for analysis.

AIMS

To detail the development, validation and utility of a new point of care (POC) test for finger-stick capillary blood concentrations of aripiprazole.

METHOD

Analytical performance (sensitivity, precision, recovery and linearity) of the assay were established using spiked whole blood and control samples of varying aripiprazole concentration. Assay validation was performed over a 14-month period starting in July 2021. Eligible patients were asked to provide a finger-stick capillary sample in addition to their usual venous blood sample. Capillary blood samples were tested by the MyCare™ Insite POC analyser, which provided measurement of aripiprazole concentration in 6 min, and the venous blood sample was tested by the standard laboratory method.

RESULTS

A total of 101 patients agreed to measurements by the two methods. Venous blood aripiprazole concentrations as assessed by the laboratory method ranged from 17 to 909 ng/mL, and from 1 to 791 ng/mL using POC testing. The correlation coefficient between the two methods (r) was 0.96 and there was minimal bias (slope 0.91, intercept 4 ng/ml).

CONCLUSIONS

The MyCare Insite POC analyser is sufficiently accurate and reliable for clinical use. The availability of this technology will improve the assessment of adherence to aripiprazole and the optimising of aripiprazole dosing.

Wireless, noninvasive therapeutic drug monitoring system for saliva measurement toward medication management of schizophrenia

As an efficient patient management tool of precision medicine, decentralized therapeutic drug monitoring (TDM) provides new vision for therapy adherence and health management of schizophrenia in a convenient manner. To dispense with psychologically burdensome blood sampling and to achieve real-time, noninvasive, and continual circulating tracking of drugs with narrow therapeutic window, we study the temporal metabolism of clozapine, an antipsychotic with severe side effect, in rat saliva by a wireless, integrated and patient-friendly smart lollipop sensing system. Highly sensitive and efficient sensing performance with acceptable anti-biofouling property was realized based on the synergistic effect of electrodeposited reduced graphene oxide and ionic liquids in pretreatment-free saliva with low detection limit and good accuracy cross-validated with conventional method. On this basis, continual salivary drug levels with distinctive pharmacokinetics were found in different routes of drug administration. Pilot experiment reveals a strong correlation between blood and saliva clozapine and a positive relationship between drug dosage and salivary drug level, indicating potential applications presented by noninvasive saliva analysis towards patient-centered and personalized pharmacotherapy and adherence management via proposed smart lollipop system.

Dried Blood Spot (DBS) as a useful tool to improve clozapine, aripiprazole and paliperidone treatment: From adherence to efficiency

INTRODUCTION

Therapeutic Drug Monitoring (TDM) of antipsychotics in schizophrenia is a powerful tool that allows tailoring the treatment in an individualized approach. Our goals are to develop and validate a Dried Blood Spot (DBS) method for monitoring some commonly used antipsychotics (aripiprazole, clozapine, and paliperidone) and to evaluate its usefulness as a compliance biomarker, as well as in drug-dose adjustment to personalize the antipsychotic treatment to improve its efficacy and safety.

METHODS

31 first-psychotic episode (FEP) and schizophrenia patients were included; 5 refer to naïve FEP who started antipsychotic treatment; 26, to patients with more than one episode and under antipsychotic treatment: aripiprazole (7 cases), clozapine (17), paliperidone (11). For DBS sample collection, 25μl of capillary blood were placed in the spot of a FTA™DMPK-C-card. After completely dryness, antipsychotics were extracted and analyzed by a validated UHPLC-MS/MS-method. DBS antipsychotic results were compared with those obtained in venous blood/plasma.

RESULTS

Aripiprazole, paliperidone and clozapine showed from good to excellent correlations between concentrations in venous blood and DBS capillary blood (r², from 0.500 to 0.721). The correlation between conventional plasma and DBS concentrations for paliperidone, aripiprazole, clozapine, and their metabolites were moderate, suggesting that optimal drug target concentrations should be established for DBS.

CONCLUSIONS

In this study, for aripiprazole, dehydroaripiprazole, paliperidone, clozapine and desmethylclozapine, DBS has provided good analytical performance for TDM. Thus, DBS sampling can offer a great alternative over conventional sampling for plasma measurement. The assay provides good analytical performances for TDM and clinical research applicability, suggesting that DBS is a promising clinical application in TDM in psychiatry.

Insight Into Corrosion of Dental Implants: From Biochemical Mechanisms to Designing Corrosion-Resistant Materials

Purpose of Review

Despite advanced technologies to avoid corrosion of dental implants, the mechanisms toward the release of metals and their role in the onset of peri-implant diseases are still under-investigated. Effective knowledge on the etiopathogenesis of corrosive products and preventive strategies mitigating the risks for surface degradation are thus in dire need. This review aimed to summarize evidence toward biocorrosion in the oral environment and discuss the current strategies targeting the improvement of dental implants and focusing on the methodological and electrochemical aspects of surface treatments and titanium-based alloys.

Recent Findings

Recent studies suggest the existence of wear/corrosion products may correlate with peri-implantitis progress by triggering microbial dysbiosis, the release of pro-inflammatory cytokines, and animal bone resorption. Furthermore, current clinical evidence demonstrating the presence of metal-like particles in diseased tissues supports their possible role as a risk factor for peri-implantitis. For instance, to overcome the drawback of titanium corrosion, researchers are primarily focusing on developing corrosion-resistant alloys and coatings for dental implants by changing their physicochemical features.

Summary

The current state-of-art discussed in this review found corrosion products effective in affecting biofilm virulence and inflammatory factors in vitro. Controversial and unstandardized data are limitations, making the premise of corrosion products being essential for peri-implantitis onset. On the other hand, when it comes to the strategies toward reducing implant corrosion rate, it is evident that the chemical and physical properties are crucial for the in vitro electrochemical behavior of the implant material. For instance, it is foreseeable that the formation of films/coatings and the incorporation of some functional compounds into the substrate may enhance the material’s corrosion resistance and biological response. Nevertheless, the utmost challenge of research in this field is to achieve adequate stimulation of the biological tissues without weakening its protective behavior against corrosion. In addition, the translatability from in vitro findings to clinical studies is still in its infancy. Therefore, further accumulation of high-level evidence on the role of corrosion products on peri-implant tissues is expected to confirm the findings of the present review besides the development of better methods to improve the corrosion resistance of dental implants. Furthermore, such knowledge could further develop safe and long-term implant rehabilitation therapy.

Heme oxygenase-1 in blood and saliva during acute psychosis: A pilot study

Despite the extensive prevalence of psychosis and schizophrenia spectrum disorders, their biological underpinnings remain largely unexplained. Recently, the overproduction of heme oxygenase-1 (HO-1), an enzyme that catalyzes the degradation of heme, was associated with oxidative stress and a neurologic phenotype similar to schizophrenia in transgenic mice. We sought to evaluate, by comparing patients experiencing an acute psychotic episode, and age/sex-matched healthy control participants, whether there was an association between HO-1 overexpression and psychosis. This cross-sectional pilot study included 16 patients and 17 control participants. Enzyme-linked immunosorbent assay and quantitative real-time polymerase chain reaction were used to quantify HO-1 expression in blood and saliva. Four psychiatric questionnaires were used to measure psychiatric symptoms in participants. Higher levels of salivary HO-1 expression were detected in patients experiencing an acute psychotic episode when compared to control participants (84.01 vs. 61.26 ng/ml, p = 0.026), but plasma and lymphocyte HO-1 expression did not significantly differ between groups. Overexpression of HO-1 in saliva specimens was also positively associated with psychiatric symptom severity and disability. The overexpression of HO-1 in the saliva of patients with psychosis suggests that it may serve as a potential biomarker for this symptom which should be explored in larger clinical trials.

A pharmacological profile of intravenous amisulpride for the treatment of postoperative nausea and vomiting

INTRODUCTION

The issue of postoperative nausea and vomiting (PONV) remains important in surgical practice, contributing to patient distress, slower recovery, and increased use of healthcare resources. Many surgical patients report it to be a worse problem than the pain. New antiemetics of different classes are still needed to help manage PONV effectively, especially the treatment of established PONV after the failure of common prophylactic antiemetics such as 5-HT₃-antagonists and corticosteroids. Intravenous amisulpride, a drug with a long history of safe use in oral form as an antipsychotic, has recently been approved in the US (trade name: Barhemsys) as an intravenous antiemetic for the prevention and treatment of PONV.

AREAS COVERED

This review article summarizes the published data on the clinical pharmacology, safety, and efficacy of intravenous amisulpride as an antiemetic, supplemented by published data on oral amisulpride, where relevant to the intravenous form. Literature was obtained via the PubMed search terms 'intravenous amisulpride' and 'amisulpride AND safety.' Both primary and secondary pharmacology are covered, along with clinical pharmacokinetics (distribution, metabolism, and excretion). The review of clinical safety and efficacy includes data from four studies in the prevention of PONV, two in the treatment of PONV and two investigating effects on the QT interval of the electrocardiogram in healthy volunteers.

EXPERT OPINION

Given the importance of sufficient PONV prevention for patients and the healthcare system, the availability of intravenous amisulpride is helpful, restoring the dopamine-antagonist class as a potential mainstay in both combination prophylaxis and treatment.

Simultaneous Quantification of Antipsychotic and Antiepileptic Drugs and Their Metabolites in Human Saliva Using UHPLC-DAD

Neuroleptics and antiepileptics are excreted in saliva, which can, therefore, be very useful in determining their concentration in the body. This study presents a method developed to simultaneously identify five neuroleptics-olanzapine, quetiapine, risperidone, aripiprazole, and clozapine-and the antiepileptic carbamazepine together with their metabolites: N-demethyl olanzapine, norquetiapine, 9-OH-risperidone, dehydroaripiprazole, N-desmethylclozapine, and carbamazepine-10,11 epoxide. Chlordiazepoxide was used as the internal standard. Strata-X-C columns were used for isolation of the compounds. Chromatographic analysis was carried out using UHPLC with a diode array detector (DAD). A mixture of acetonitrile and water with the addition of formic acid and 0.1% triethylamine was used as the mobile phase. The developed method was validated by determining the linearity for all analytes in the range 10-1000 ng/mL and the value of R² > 0.99. Intra- and inter-day precision were also determined, and the relative standard deviation (RSD) value in both cases did not exceed 15%. To determine the usefulness of the developed method, saliva samples were collected from 40 people of both sexes treated with the tested active substances both in monotherapy and in polypragmasy. In all cases, the active substances tested were identified.

Determination of antipsychotic drugs in oral fluid using dried saliva spots by gas chromatography-tandem mass spectrometry

The present work describes the optimization and validation of an analytical method for the determination of six antipsychotic drugs (chlorpromazine, levomepromazine, cyamemazine, clozapine, haloperidol, and quetiapine) in oral fluid samples after solvent extraction from dried saliva spots, by gas chromatography coupled to tandem mass spectrometry. The method was fully validated, and the included parameters were selectivity, linearity, limits of quantification, precision and accuracy, stability, and recovery. The method was linear for all compounds from 10 to 400 ng/mL, except for haloperidol (5-100 ng/mL), presenting coefficients of determination higher than 0.99. Inter- and intra-day precision and accuracy were in conformity with the criteria usually seen in bioanalytical method validation; i.e., coefficients of variation were lower than 15% and an accuracy of 15% or better for all studied drugs. The recoveries obtained with this miniaturized technique ranged from 63 to 97%. The herein described method is the first to be reported using the dried saliva spots approach for the analysis of these antypshychotic drugs, proving great sensitivity apart from its simple and fast procedure. The method was considered a good alternative to the conventional techniques to be applied in clinical and toxicological analyses, even more taking into account the extremely low sample volume used (50 μL). Graphical abstract.

Development and validation of a gas chromatography/tandem mass spectrometry method for simultaneous quantitation of several antipsychotics in human plasma and oral fluid

RATIONALE

Antipsychotic drugs are prescription medications used to treat psychotic disorders, such as schizophrenia, schizoaffective disorder, or psychotic depression. With several antipsychotic drugs currently available all over the world, this class of drugs has quickly gained importance in both the clinical and forensic context. This work describes the development and validation of a methodology for the determination of seven antipsychotic drugs in plasma and oral fluid samples.

METHODS

The antipsychotic drugs (chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine, cyamemazine and, levomepromazine) were isolated from 0.2 mL of oral fluid and 0.5 mL of plasma using solid-phase extraction (SPE) following analysis by gas chromatography/tandem mass spectrometry (GC/MS/MS). The method was validated according to the international guidelines in terms of selectivity, linearity, accuracy, precision and recovery.

RESULTS

The procedure was linear within 2-600 ng/mL (plasma) and 2-400 ng/mL (oral fluid), the intervals varying according to the compound; a mean R² value of 0.99 was obtained and the calibrator's accuracy (mean relative error) was within a ±15 % interval for all concentrations. The limits of detection ranged from 1 to 10 ng/mL. Within- and between-run precision and accuracy were acceptable for all studied compounds. The extraction efficiency of the process ranged from 79% to 95%. The method was applied to authentic specimens.

CONCLUSIONS

The described method was proven selective and sensitive for the determination of antipsychotics in low sample volumes using SPE and GC/MS/MS. This method was considered suitable not only for routine analysis of patients undergoing antipsychotic treatment (to evaluate compliance), but also in forensic scenarios where the studied compounds may be involved. To the best of our knowledge, this is the first work that reports the determination of antipsychotic drugs in oral fluid using MS/MS.

Solid Phase Extraction Purification of Saliva Samples for Antipsychotic Drug Quantitation

Saliva is far less popular as a diagnostic material than blood. This has resulted in a lack of procedures for the sampling and handling of saliva, e.g., effective ways to purify endogenous compounds from saliva to enable a simultaneous determination of xenobiotics such as neuroleptics. Therefore, the aim of this study was to develop an analytical procedure to purify saliva samples so that it is then possible to simultaneously determine five neuroleptics (aripiprazole, clozapine, olanzapine, quetiapine and risperidone) and the antiepileptic drug carbamazepine, and their respective metabolites (dehydroaripiprazole, N-desmethylclozapine, N-demethylolanzapine, norquetiapine, 9-OH-risperidone and carbamazepine-10,11-epoxide). A study of three types of solid-phase extraction (SPE) columns showed that the purest eluates were obtained using columns containing ion exchange sorbent. The sorbents were first washed with water then with a mixture of water and methanol (1:1), and the adsorbed residue was eluted with a 5% ammonia solution in methanol. Saliva samples for SPE were diluted with 2% formic acid and a mixture of methanol and water (1:1). This procedure was developed to purify a saliva sample spiked with a mixture of neuroleptics and carbamazepine, and their respective metabolites. A chromatographic analysis confirmed the isolation of all compounds, indicating that this procedure can be used in further development and validation for a method designed to monitor the levels of neuroleptic drugs in saliva and to monitor their uptake by patients.

The Saliva Exposome for Monitoring of Individuals' Health Trajectories

BACKGROUND

There is increasing evidence that environmental, rather than genetic, factors are the major causes of most chronic diseases. By measuring entire classes of chemicals in archived biospecimens, exposome-wide association studies (EWAS) are being conducted to investigate associations between a myriad of exposures received during life and chronic diseases.

OBJECTIVES

Because the intraindividual variability in biomarker levels, arising from changes in environmental exposures from conception onwards, leads to attenuation of exposure-disease associations, we posit that saliva can be collected repeatedly in longitudinal studies to reduce exposure-measurement errors in EWAS.

METHODS

From the literature and an open-source saliva-metabolome database, we obtained concentrations of 1,233 chemicals that had been detected in saliva. We connected salivary metabolites with human metabolic pathways and PubMed Medical Subject Heading (MeSH) terms, and performed pathway enrichment and pathway topology analyses.

RESULTS

One hundred ninety-six salivary metabolites were mapped into 49 metabolic pathways and connected with human metabolic diseases, central nervous system diseases, and neoplasms. We found that the saliva exposome represents at least 14 metabolic pathways, including amino acid metabolism, TCA cycle, gluconeogenesis, glutathione metabolism, pantothenate and CoA biosynthesis, and butanoate metabolism.

CONCLUSIONS

Saliva contains molecular information worthy of interrogation via EWAS. The simplicity of specimen collection suggests that saliva offers a practical alternative to blood for measurements that can be used to characterize individual exposomes. https://doi.org/10.1289/EHP1011.

Investigation of Saliva as an Alternative to Plasma Monitoring of Voriconazole

BACKGROUND AND OBJECTIVES

Therapeutic drug monitoring (TDM) of voriconazole is increasingly being implemented in clinical practice. However, as blood sampling can be difficult in paediatric and ambulatory patients, a non-invasive technique for TDM is desirable. The aim of this study was to compare the pharmacokinetics of voriconazole in saliva with the pharmacokinetics of unbound and total voriconazole in plasma in order to clinically validate saliva as an alternative to plasma in voriconazole TDM.

METHODS

In this pharmacokinetic study, paired plasma and saliva samples were taken at steady state in adult haematology and pneumology patients treated with voriconazole. Unbound and bound plasma voriconazole concentrations were separated using high-throughput equilibrium dialysis. Voriconazole concentrations were determined with liquid chromatography-tandem mass spectrometry. Pharmacokinetic parameters were calculated using log-linear regression.

RESULTS

Sixty-three paired samples were obtained from ten patients (seven haematology and three pneumology patients). Pearson's correlation coefficients (R values) for saliva versus unbound and total plasma voriconazole concentrations showed a very strong correlation, with values of 0.970 (p < 0.001) and 0.891 (p < 0.001), respectively. Linear mixed modelling revealed strong agreement between voriconazole concentrations in saliva and unbound plasma voriconazole concentrations, with a mean bias of -0.03 (95 % confidence interval -0.14 to 0.09; p = 0.60). For total concentrations below 10 mg/L, the mean ratio of saliva to total plasma voriconazole concentrations was 0.51 ± 0.08 (n = 63), which did not differ significantly (p = 0.76) from the unbound fraction of voriconazole in plasma of 0.49 ± 0.03 (n = 36).

CONCLUSIONS

Saliva can serve as a reliable alternative to plasma in voriconazole TDM, and it can easily be implemented in clinical practice.

Are capillary DBS applicable for therapeutic drug monitoring of common antipsychotics? A proof of concept

AIM

DBS sampling has been proposed as an alternative for venous blood collection in therapeutic drug monitoring (TDM) of antipsychotics. For implementation in routine practice, a comparison between capillary and venous blood concentrations is mandatory.

RESULTS

A DBS method for quantification of antipsychotics was clinically validated. First, whole blood therapeutic ranges were calculated using the blood:serum ratio. Calculation of DBS:blood ratios and Passing-Bablok regression analysis demonstrated that concentrations obtained by DBS analysis were highly comparable to those obtained by conventional whole blood analysis. Clinical interpretation of serum, whole blood and DBS concentrations were highly identical (sensitivity 91.6-97.6%).

CONCLUSION

This is the first clinical study demonstrating the value of DBS sampling in TDM of antipsychotics.

Current advances in biosampling for therapeutic drug monitoring of psychiatric CNS drugs

Many CNS drugs are effective for the treatment of psychiatric disorders. Psychotropic drugs work differently, thus clinical outcomes for many patients may be insufficient. For this reason it could be useful the measurement of drug levels for clinical decision-making. Analytical goals in therapeutic drug monitoring (TDM) should be established by selecting the appropriate biological matrix. The aim of this review is to highlight the usefulness of TDM for antiepileptics, antidepressants and antipsychotics, with a focus on current advances in biosampling. The literature on TDM was reviewed up to March 2015. An overview on the use of alternative biological matrices is provided to address the current issues and advances in the field of biosampling for psychiatric CNS drug TDM.

Advances in detection of antipsychotics in biological matrices

Measuring antipsychotic concentrations in human matrices is important for both therapeutic drug monitoring and forensic toxicology. This review provides a critical overview of the analytical methods for detection and quantification of antipsychotics published in the last four years. Focus lies on advances in sample preparation, analytical techniques and alternative matrices. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is used most often for quantification of antipsychotics. This sensitive technique makes it possible to determine low concentrations not only in serum, plasma or whole blood, but also in alternative matrices like oral fluid, dried blood spots, hair, nails and other body tissues. Current literature on analytical techniques for alternative matrices is still limited and often requires a more thorough validation including a comparison between conventional and alternative results to determine their actual value. Ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) makes it possible to quantify a high amount of compounds within a shorter run time. This technique is widely used for multi-analyte methods. Only recently, high-resolution mass spectrometry has gained importance when a combination of screening of (un)known metabolites, and quantification is required.

Quantitative measurement of XLR11 and UR-144 in oral fluid by LC-MS-MS

Availability and consumption of synthetic cannabinoids have risen recently in the USA and Europe. These drugs have adverse effects, including acute psychosis and bizarre behavior. In 2012, the United States Drug Enforcement Agency permanently banned five of the synthetic cannabinoids and in 2013, temporarily added XLR11, UR-144 and AKB48 to Schedule I of the Controlled Substances Act. As synthetic cannabinoid strains are added to the Schedule I list, new strains are being introduced into the market. XLR11 and UR-144 are two of the most recent additions to the synthetic cannabinoid drug class. To test collected oral fluid samples for XLR11 and UR-144, we developed a bioanalytical method that initially purifies the sample with solid-phase extraction and then quantitatively identifies the drugs with ultra-high-performance liquid chromatography-tandem mass spectrometry. The method was validated according to United States Food and Drug Administration guidelines and Scientific Working Group for Forensic Toxicology guidelines and the validation data showed that the method is an accurate, precise, robust and efficient method suited for high-throughput toxicological screening applications. We tested human subject samples with the developed method and found the presence of parent drugs (XLR11 and UR-144), their metabolites and their pyrolysis products in oral fluid.

Clinical pharmacokinetics of tyrosine kinase inhibitors: implications for therapeutic drug monitoring

The treatment of many malignancies has been improved in recent years by the introduction of molecular targeted therapies. These drugs interact preferentially with specific targets that are mutated and/or overexpressed in malignant cells. A group of such targets are the tyrosine kinases, against which a number of inhibitors (tyrosine kinase inhibitors, TKIs) have been developed. Imatinib, a TKI with targets that include the breakpoint cluster region-Abelson (bcr-abl) fusion protein kinase and mast/stem cell growth factor receptor kinase (c-Kit), was the first clinically successful drug of this type and revolutionized the treatment and prognosis of chronic myeloid leukemia and gastrointestinal stromal tumors. This success paved the way for the development of other TKIs for the treatment of a range of hematological malignancies and solid tumors. To date, 14 TKIs have been approved for clinical use and many more are under investigation. All these agents are given orally and are substrates of a range of drug transporters and metabolizing enzymes. In addition, some TKIs are capable of inhibiting their own transporters and metabolizing enzymes, making their disposition and metabolism at steady-state unpredictable. A given dose can therefore give rise to markedly different plasma concentrations in different patients, favoring the selection of resistant clones in the case of subtherapeutic exposure, and increasing the risk of toxicity if dosage is excessive. The aim of this review was to summarize current knowledge of the clinical pharmacokinetics and known adverse effects of the TKIs that are available for clinical use and to provide practical guidance on the implications of these data in patient management, in particular with respect to therapeutic drug monitoring.

A validated GC/MS method for the determination of amisulpride in whole blood

A sensitive GC/MS method for the determination of amisulpride in whole blood was developed, optimized and validated. Sample preparation included solid-phase extraction using HF Bond Elut C18 cartridges and further derivatization with heptafluorobutyric anhydride (HFBA). The limits of detection and quantification were 3.00 and 10.0 μg/L, respectively. The calibration curves were linear up to 1000 μg/L (R(2)≥0.991). Absolute recovery ranged from 94.2 to 101%. Accuracy was found to be between -8.7 and 1.9% and imprecision was less than 10.0%. The developed method covers the generally accepted therapeutic range but it can also cover levels above them. This makes our method suitable for the determination of amisulpride not only for clinical purposes on psychiatric patients, but also during the investigation of forensic cases where amisulpride is involved.

LC-MS/MS of some atypical antipsychotics in human plasma, serum, oral fluid and haemolysed whole blood

Therapeutic drug monitoring (TDM) of atypical antipsychotics is common, but published methods often specify relatively complex sample preparation and analysis procedures. The aim of this work was to develop and validate a simple liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the analysis of amisulpride, aripiprazole and dehydroaripiprazole, clozapine and norclozapine, olanzapine, quetiapine, risperidone and 9-hydroxyrisperidone, and sulpiride in small (200 μL) volumes of plasma or serum for TDM purposes. The applicability of the method as developed to haemolysed whole blood and to oral fluid was also investigated. Analytes and internal standards were extracted into butyl acetate:butanol (9+1, v/v) and a portion of the extract analysed by LC-MS/MS (100 mm × 2.1 mm i.d. Waters Spherisorb S5SCX; eluent: 50 mmol/L methanolic ammonium acetate, pH* 6.0; flow-rate 0.5 mL/min; positive ion APCI-SRM, two transitions per analyte). Assay calibration (human plasma, oral fluid, and haemolysed whole blood calibration solutions) was performed by plotting the ratio of the peak area of the analyte to that of the appropriate internal standard. Assay validation was as per FDA guidelines. Assay calibration was linear across the concentration ranges studied. Inter- and intra-assay precision and accuracy were within 10% for all analytes in human plasma. Similar results were obtained for oral fluid and haemolysed whole blood, except that aripiprazole and dehydroaripiprazole were within 15% accuracy at low concentration (15 μg/L) in oral fluid, and olanzapine inter-assay precision could not be assessed in these matrices due to day-by-day degradation of this analyte. Recoveries varied between 16% (sulpiride) and 107% (clozapine), and were reproducible as well as comparable between human plasma, human serum, calf serum and haemolysed whole blood. For oral fluid, recoveries were reproducible, but differed slightly from those in plasma suggesting the need for calibration solutions to be prepared in this medium if oral fluid is to be analysed. LLOQs were 1-5 μg/L depending on the analyte. Neither ion suppression/enhancement, nor interference from some known metabolites of the antipsychotics studied has been encountered. The method has also been applied to the analysis of blood samples collected post-mortem after dilution (1+1, 1+3; v/v) in analyte-free calf serum.