Simultaneous determination of clozapine, olanzapine, risperidone and quetiapine in plasma by high-performance liquid chromatography-electrospray ionization mass spectrometry

Chromatographic Methods for the Analysis of the Antipsychotic Drug Clozapine and Its Major Metabolites: A Review

Clozapine (CLZ), a second-generation antipsychotic, can effectively reduce schizophrenia, bipolar disorder and major depression symptoms. This review provides an overview of all reported chromatographic methods (62 references) for the quantification of CLZ and its two main metabolites, norclozapine and clozapine N-oxide in pharmaceutical formulations, biological matrices and environmental samples.

Long-term stability of five atypical antipsychotics (risperidone, olanzapine, paliperidone, clozapine, quetiapine) and the antidepressant mirtazapine in human serum assessed by a validated SPE LC-MS/MS method

Long-term sample stability of five atypical antipsychoticdrugs risperidone, paliperidone, clozapine, quetiapine and olanzapine and the antidepressant drug mirtazapine in serum was studied by use of a newly developed and validated analytical method based on solid-phase extraction and liquid chromatography-tandem mass spectrometry. Ascorbic acid was used as an antioxidative agent to stabilize olanzapine during storage and sample preparation. We assessed analyte stability on long-term storage in serum samples at 25°C, 5°C, -20°C and -80°C, and during five freeze-thaw cycles. Analytes were stable for 23 days at room temperature except for olanzapine and mirtazapine (17 days). All analytes were stable for at least 30 days at 5°C. All analytes were stable for 270 days at -20°C, except for paliperidone and mirtazapine with 60 days and 180 days, respectively. All analytes were stable for 270 days at -80°C. Furthermore, all analytes were stable for five freeze-thaw cycles. We recommend storage at -80°C when samples drawn for analysis of antipsychotic drugs are stored for more than 60 days, whereas a temperature of -20°C is sufficient for storage less than 60 days.

A Simple HPLC-DAD Method for the Therapeutic Monitoring of Clozapine and Related Metabolites in Human Plasma and Urine Samples

Clozapine and its metabolites require close therapeutic monitoring (TDM) in patients due to poor correlation between the administrated doses and resulting plasma concentrations, the narrow therapeutic interval, high inter-individual variability, and the risk of serious side effects once toxic levels are exceeded. The aim of the study was to develop a simple (relatively cheap) LC-UV method for the quantification of clozapine and its metabolites in plasma and urine samples. For sample preparation, liquid-liquid extraction (LLE) in n-octanol was more efficient and less limiting in injection volumes compared to the in-situ formation of SUPRAS. When analyzing urine, an alkalinization step before extraction was required. The proposed method produced linear concentration responses with/without internal standard (IS) for the target analytes, with LLOQs within the targeted range of 50 ppb and %RSD within the acceptable 15% range. Furthermore, sample stability studies proved that pre-extracted samples were stable for the short term at room temperature and long-term when frozen.

Quetiapine Fumarate: A Review of Analytical Methods

Atypical antipsychotics are newer second-generation antipsychotics with weak dopamine type 2 blocking but potent 5-HT2 antagonistic activity. They are considered first-line treatments for schizophrenia and gradually replace typical antipsychotics. Extrapyramidal side effects are minimal, and they tend to improve impaired cognitive function in psychotics. Quetiapine fumarate is an atypical antipsychotic drug used to treat schizophrenia, mania and depression in people with bipolar disorder combined with other drugs or alone. Quetiapine was developed in 1985 and approved for medical use in the USA in 1997. Thorough computer-aided literature, surveys revealed that numerous analytical methods were reported over the years. The present study reviews analytical methods with their validation parameters published during the last 22 years (1999-2021) either as a single entity or combination in dosage form, and determination from biological samples. Novel strategies for increasing separation quality, such as QbD analysis and green spectroscopy, were discovered during the evaluation, and this review can be utilized for further research reference.

[Therapeutic drug monitoring of olanzapine]

Olanzapine, atypical antipsychotic, is used to treat schizophrenia and bipolar disorder. Its therapeutic drug monitoring (TDM) is quite commonly done. Olanzapine is well absorbed orally (bioavailability: 85 %), with peak plasma occurring between 4 and 6hours after oral administration. It is extensively metabolized by different hepatic enzymes (including CYP1A2 and CYP2D6 isoforms) to a large number of inactive metabolites, and its half-life is between 30 and 60hours. No specific therapeutic range, or threshold concentration could not be a consensus, but the higher intra- and interindividual variability, as well as the existence of studies suggesting a correlation between circulating concentrations of olanzapine and occurrence of therapeutic relapse or toxic phenomena appear to justify the STP for this molecule. Given these data, the interest of the STP was evaluated for this molecule to: recommended with therapeutic window of 20μg/L to 80μg/L.

Noninvasive drug adherence monitoring of antipsychotic patients via finger sweat testing

Collection of finger sweat is explored here as a rapid and convenient way of monitoring patient adherence to antipsychotic drugs. Finger sweat samples (n = 426) collected from patients receiving treatment with clozapine, quetiapine and olanzapine were analysed by liquid chromatography mass spectrometry, including a subgroup of patients with paired plasma samples. Finger sweat samples were also analysed from a negative control group and patients who had handled antipsychotic medication only. The finger sweat test (based on the detection of parent drug in one donated sample) was 100% effective in monitoring adherence within commonly prescribed dosing ranges. In comparison to participants who handled the medication only, the test could distinguish between contact and administration through monitoring of the drug metabolite, or the level of parent drug. Additionally, in a subgroup of patients prescribed clozapine, a statistically significant correlation was observed between the mass of parent drug in finger sweat and plasma concentration. The finger sweat technology shows promise as a dignified, noninvasive method to monitor treatment adherence in patients taking antipsychotics.

Deep Learning Methods Applied to Drug Concentration Prediction of Olanzapine

Pharmacometrics and the utilization of population pharmacokinetics play an integral role in model-informed drug discovery and development (MIDD). Recently, there has been a growth in the application of deep learning approaches to aid in areas within MIDD. In this study, a deep learning model, LSTM-ANN, was developed to predict olanzapine drug concentrations from the CATIE study. A total of 1527 olanzapine drug concentrations from 523 individuals along with 11 patient-specific covariates were used in model development. The hyperparameters of the LSTM-ANN model were optimized through a Bayesian optimization algorithm. A population pharmacokinetic model using the NONMEM model was constructed as a reference to compare to the performance of the LSTM-ANN model. The RMSE of the LSTM-ANN model was 29.566 in the validation set, while the RMSE of the NONMEM model was 31.129. Permutation importance revealed that age, sex, and smoking were highly influential covariates in the LSTM-ANN model. The LSTM-ANN model showed potential in the application of drug concentration predictions as it was able to capture the relationships within a sparsely sampled pharmacokinetic dataset and perform comparably to the NONMEM model.

Selective Spectrofluorimetric Approach for the Assessment of Two Antipsychotic Drugs through Derivatization with O-Phthalaldehyde

A facile and sensible spectrofluorimetric approach for the measurement of two antipsychotic medications, aripiperazole (ARP) and clozapine (CLZ), was devised and validated. The approach involves reacting the examined medicines with o-phthalaldehyde in the presence of β-mercaptoethanol in a borate buffer of pH 9.0 and pH 10 for ARP and CLZ, respectively, to produce a robustly fluorescent compound that is detected at 450 nm following excitation at 340 nm. The experimental variables influencing the performance and product stability were thoroughly investigated and optimized. Under optimal conditions, the intensity of the fluorescence was linear during a concentration range of 0.1–0.5 μg/mL, with a limit of detection (0.0391 and 0.0400 μg/mL) and limit of quantitation (0.1035 and 0.1332 μg/mL), respectively, for ARP and CLZ. The suggested approach was successful in analyzing commercialized tablets. A statistical investigation of the results produced by the suggested and standard methods showed no remarkable variation in the precision and accuracy of the two approaches. A chemical mechanism using o-phthalaldehyde was proposed.

Olanzapine-induced lipid disturbances: A potential mechanism through the gut microbiota-brain axis

Objective: Long-term use of olanzapine can induce various side effects such as lipid metabolic disorders, but the mechanism remains to be elucidated. The gut microbiota-brain axis plays an important role in lipid metabolism, and may be related to the metabolic side effects of olanzapine. Therefore, we explored the mechanism by which olanzapine-induced lipid disturbances through the gut microbiota-brain axis.

Methods: Sprague Dawley rats were randomly divided into two groups, which underwent subphrenic vagotomy and sham surgery. Then the two groups were further randomly divided into two subgroups, one was administered olanzapine (10 mg/kg/day) by intragastric administration, and the other was administered normal saline by intragastric administration (4 ml/kg/day) for 2 weeks. The final changes in lipid parameters, gut microbes and their metabolites, and orexin-related neuropeptides in the hypothalamus were investigated among the different groups.

Results: Olanzapine induced lipid disturbances as indicated by increased weight gain, elevated ratio of white adipose tissue to brown adipose tissue, as well as increased triglyceride and total cholesterol. Olanzapine also increased the Firmicutes/Bacteroides (F/B) ratio in the gut, which was even aggravated by subphrenic vagotomy. In addition, olanzapine reduced the abundance of short-chain fatty acids (SCFAs) metabolism related microbiome and 5-hydroxytryptamine (5-HT) levels in the rat cecum, and increased the gene and protein expression of the appetite-related neuropeptide Y/agouti-related peptide (NPY/AgRP) in the hypothalamus.

Conclusion: The abnormal lipid metabolism caused by olanzapine may be closely related to the vagus nerve-mediated gut microbiota-brain axis.

Fabrication and Characterization of Fast-Dissolving Films Containing Escitalopram/Quetiapine for the Treatment of Major Depressive Disorder

Major depressive disorder (MMD) is a leading cause of disability worldwide. Approximately one-third of patients with MDD fail to achieve response or remission leading to treatment-resistant depression (TRD). One of the psychopharmacological strategies to overcome TRD is using a combination of an antipsychotic as an augmenting agent with selective serotonin reuptake inhibitors (SSRIs). Among which, an atypical antipsychotic, quetiapine (QUE), and an SSRI, escitalopram (ESC), were formulated as a fixed-dose combination as a fast-dissolving film by coaxial electrospinning. The resultant fiber’s morphology was studied. SEM images showed that the drug-loaded fibers were smooth, un-beaded, and non-porous with a fiber diameter of 0.9 ± 0.1 µm, while the TEM images illustrated the distinctive layers of the core and shell, confirming the successful preparation of these fibers. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) studies confirmed that both drugs were amorphously distributed within the drug-loaded fibers. The drug-loaded fibers exhibited a disintegration time of 2 s, which accelerated the release of both drugs (50% after 5 min) making it an attractive formulation for oral mucosal delivery. The ex vivo permeability study demonstrated that QUE was permeated through the buccal membrane, but not ESC that might be hindered by the buccal epithelium and the intercellular lipids. Overall, the developed coaxial fibers could be a potential buccal dosage form that could be attributed to higher acceptability and adherence among vulnerable patients, particularly mentally ill patients.

A Comprehensive Review on Importance and Quantitation of Atypical Antipsychotic Drugs and their Active Metabolites in Commercial Dosage Forms

Background:

Schizophrenia is a severe mental illness that affects more than twenty-one million people throughout the world. Schizophrenia also causes early death. Schizophrenia and other related psychotic ailments are controlled by the prescription of antipsychotic drugs, which act by blocking certain chemical receptors in the brain and thus relieves the symptoms of psychotic disorder. These drugs are present in the different dosage forms in the market and provided in a certain amount as per the need of the patients.

Objective:

Since such medications treat mental disorders, it is very important to have a perfect and accurate dose so that the risk factor is not affected by a higher or lower dose, which is not sufficient for the treatment. For accurate assay of these kinds of drugs, different analytical methods were developed ranging from older spectrophotometric techniques to latest hyphenated methods.

Results:

The current review highlights the role of different analytical techniques that were employed in the determination and identification of antipsychotic drugs and their metabolites. Techniques such as spectrophotometry, fluorimetry, liquid chromatography, liquid chromatography-mass spectrometry, gas chromatography, and gas chromatography-mass spectrometry employed in the method development of such antipsychotic drugs were reported in the review. Different metabolites, identified using the hyphenated techniques, were also mentioned in the review. The synthesis pathways of few of the metabolites were mentioned.

Conclusion:

The review summarizes the analyses of different antipsychotic drugs and their metabolites. A brief introduction of illnesses and their symptoms and possible medications were highlighted. Synthesis pathways of the associated metabolites were also mentioned.

A simple and rapid LC-MS/MS method for the simultaneous determination of eight antipsychotics in human serum, and its application to therapeutic drug monitoring

A simple and rapid liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed and used to determine eight antipsychotics (aripiprazole, clozapine, haloperidol, olanzapine, paliperidone, quetiapine, risperidone, and ziprasidone) in human serum for practical clinical usage. Stable isotope-labeled internal standards were used for all drugs to compensate for method variability, including matrix effects, ion extraction and ionization variations. Samples were prepared by simple protein precipitation with methanol. Chromatographic separation was accomplished in less than 3.3 min on a KINTEX C18 column (50 mm × 3.0 mm, 5 μm) using a gradient elution of 2 mM aqueous ammonium formate and methanol at a flow rate of 0.5 mL/min. Quantification was performed by multiple reaction monitoring (MRM) in the positive mode. The method was fully validated according to the latest recommendations of international guidelines. The correlation coefficients of calibration curves were all greater than 0.9945. Internal standard-normalized matrix effects ranged from 96.3% to 115%, and extraction recoveries were between 88.1% and 107%. Coefficients of variation ranged from 1.82 - 13.5% for intra-day precision, 5.69-14.7% for inter-day precision, and the relative error for accuracy did not exceed ± 13.5% for any analyte. The method was successfully applied to routine clinical therapeutic drug monitoring for 2,173 samples.

Development and validation of solid-phase extraction coupled with a liquid chromatography-tandem mass spectrometry method for quantitation of olanzapine in saliva

Olanzapine is one of the most commonly used drugs for the treatment of schizophrenia and depression of various origins. Its levels are usually measured in the blood, but the collection of this diagnostic material poses many problems. Therefore, we aimed to develop a fast and sensitive method to determine olanzapine levels in saliva, an easily available diagnostic material. To reduce the consumption of toxic solvents during analyte extraction from saliva, olanzapine was isolated by solid-phase extraction using Oasis® MCX cartridges. Chromatographic analysis was performed by LC-MS/MS, with C18 resin in Atlantis® T3 column as the stationary phase and 2 mM ammonium formate and acetonitrile as the mobile phase (flow rate of 0.25 mL/min, with elution gradient). The specificity, linearity, sensitivity, precision, accuracy, and stability of the optimized method were validated. The relative standard deviation for intra-day precision for three tested olanzapine concentrations did not exceed 12.7%; the highest accuracy value was 113.9%. The recoveries from spiked saliva samples were greater than 87.3% for the two olanzapine concentrations studied. The developed method was then used to determine olanzapine levels in human saliva obtained from 15 patients treated with different doses of olanzapine.

Optimized UPLC-MS/MS method for the quantitation of olanzapine in human plasma: application to a bioequivalence study

Aim: Olanzapine (OLZ) is the first-line, cost-effectiveness treatment for schizophrenia in China. A quantitative ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for determination of OLZ in human plasma was developed. Results: LC separation was achieved on Waters XBrige C₁₈ column. ESI⁺ was involved and multiple reaction monitoring transitions were at m/z 313.2→256.1 for OLZ and m/z 316.2→256.1 IS (d3-OLZ). The linear range was 0.1-20 ng/ml with LLOQ of 0.1 ng/ml. Accuracy and precision were within 10%. The validated method was successfully applied to a bioequivalence study of OLZ disintegrating tablets at dose of 5 mg with 100% reproducibility evaluated by incurred sample reanalysis. Conclusion: A robust validated method was developed for quantitation of OLZ in human plasma.

Effect of Clozapine on Anti-N-Methyl-D-Aspartate Receptor Encephalitis With Psychiatric Symptoms: A Series of Three Cases

The main clinical manifestations of anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis are acute or subacute seizures, cognition impairment, and psychiatric symptoms. Nowadays, the scheme of antipsychotic therapy for this disease has not been established. This study reports three cases of anti-NMDAR encephalitis with psychiatric symptoms. The anti-NMDAR antibodies in cerebrospinal fluid (CSF) and serum were positive. The psychiatric symptoms still existed after intravenous immunoglobulin (IVIG) treatment; thus, clozapine was used for antipsychotic therapy. Case 1 was a 37-year-old man who suffered from bad mood and suicide behaviors for 1 month. Hallucination and delusion still existed after IVIG treatment and hormone therapy, and the symptoms were relieved when given clozapine for 12 months. Case 2 was a 28-year-old man who was admitted to our hospital due to injuring other people and destructive behaviors for 2 days. He showed irritability, bad temper, declined cognition, and severe delusion of persecution after IVIG treatment and hormone therapy, but the psychiatric symptoms disappeared when given clozapine for 3 months. Case 3 was a 23-year-old man who suffered from headache and babbing for 7 days. Symptoms such as irritability, bad temper, babbing, and injuring other people still existed after IVIG treatment and hormone therapy, but they disappeared when given clozapine for 2 months. Therefore, we suggest that during the treatment of anti-NMDAR encephalitis with psychiatric symptoms, if the anti-NMDAR antibodies in CSF and serum were positive, and psychiatric symptoms could not be controlled after IVIG and hormone therapy, clozapine may work.

Determination of quetiapine in human plasma by LC-MS/MS and its application in a bioequivalence study

A selective, sensitive and simple high performance liquid chromatography tandem mass spectrometric (HPLC-MS/MS) method for determining quetiapine in human plasma was developed and validated. One-step protein precipitation with acetonitrile was used to pretreat plasma samples. Carbamazepine was used as internal standard. An automated liquid handling workstation with 96-well protein precipitate plate was used to facilitate the process. The chromatographic separation was achieved on a Waters Xbridge C₁₈ column (3.5μm, 2.1mm×50mm). Gradient elution was set with a mobile phase of acetonitrile/water (containing 10mM ammonium acetate and 0.1% formic acid).The flow rate was 0.4mL/min and total analytical run time was 3min. The analysis was conducted using a triple quadrupole tandem mass spectrometer with an electrospray ionization source operating in positive ion mode. The multiple reaction monitoring of transition were m/z 384.2→253.1 for quetiapine and m/z 237.0→194.0 for carbamazepine, respectively. The linear concentration range for the standard curve of quetiapine was 0.5-400ng/mL for a 5μL injection of the pretreated sample (original plasma sample, 50μL). The intra-day and inter-day accuracy and precision were all less than 15%. The method was successfully used in a bioequivalence study comparing two quetiapine extended-release tablets in Chinese volunteers.

New Modified UPLC/Tandem Mass Spectrometry Method for Determination of Risperidone and Its Active Metabolite 9-Hydroxyrisperidone in Plasma: Application to Dose-Dependent Pharmacokinetic Study in Sprague-Dawley Rats

Sensitive and specific liquid-chromatography tandem mass spectrometry (UPLC-MS/MS) assay has been developed and validated for simultaneous quantification of risperidone (RIS) and its active metabolite 9-hydroxyrisperidone (9-OH-RIS) in rat plasma using olanzapine (OLA) as internal standard (IS). Pharmacokinetics of risperidone and its active metabolite 9-hydroxyrisperidone was compared across different doses (0.3, 1.0, and 6.0 mg/kg). Serial blood sample was collected over a time of 48 hours and analyzed for risperidone and its active metabolite 9-hydroxyrisperidone. The pharmacokinetics parameters including C_max, t_max, and AUC were determined for risperidone and its active ingredient. The method was linear in the concentration range of 0.2–500 ng/mL for risperidone and 9-OH-risperidone, with coefficients of determination greater than 0.998 and lower limit of quantitation of 0.2 ng/mL. Blood levels of risperidone and its active metabolite were roughly dose-proportional. The method developed herein is simple and rapid and was successfully applied for dose-dependent pharmacokinetic study.

Rapid determination of some psychotropic drugs in complex matrices by tandem dispersive liquid-liquid microextraction followed by high performance liquid chromatography

Simple and rapid determinations of some psychotropic drugs in some pharmaceutical wastewater and human plasma samples were successfully accomplished via the tandem dispersive liquid-liquid microextraction combined with high performance liquid chromatography-ultraviolet detection (TDLLME-HPLC-UV). TDLLME of the three psychotropic drugs clozapine, chlorpromazine, and thioridazine was easily performed through two consecutive dispersive liquid-liquid microextractions. By performing this convenient method, proper sample preconcentrations and clean-ups were achieved in just about 7min. In order to achieve the best extraction efficiency, the effective parameters involved were optimized. The optimal experimental conditions consisted of 100μL of CCl₄ (as the extraction organic solvent), and the pH values of 13 and 2 for the donor and acceptor phases, respectively. Under these optimum experimental conditions, the proposed TDLLME-HPLC-UV technique provided a good linearity in the range of 5-3000ngmL^-1 for the three psychotropic drugs with the correlation of determinations (R²s) higher than 0.996. The limits of quantification (LOQs) and limits of detection (LODs) obtained were 5.0ngmL^-1 and 1.0-1.5ngmL^-1, respectively. Also the proper enrichment factors (EFs) of 96, 99, and 88 for clozapine, chlorpromazine, and thioridazine, respectively, and good extraction repeatabilities (relative standard deviations below 9.3%, n=5) were obtained.

Development and validation of HILIC-ESI/MS/MS methods for simultaneous quantitation of several antipsychotics in human plasma and blood

BACKGROUND

Knowledge of antipsychotic drug levels at point of care (POC) may significantly aid therapeutic decision-making. To support the development of future POC devices and to validate the use of fingerstick capillary blood sampling, two robust hydrophilic interaction LC-ESI/MS/MS methods were developed and validated. Two PK studies were completed evaluating the correlation between fingerstick blood and plasma concentrations with corresponding venous blood and plasma concentrations for several commonly prescribed atypical antipsychotics and selected metabolites. Sensitive and reliable LC-MS/MS bioanalytical assays were developed to support these studies.

RESULTS

Three methods, requiring only 25-μl matrix volumes, were developed using supported liquid extraction with hydrophilic interaction LC-MS/MS detection and validated according to regulatory guidance.

CONCLUSION

Robust and efficient LC-MS/MS assays were established and were effective in providing antipsychotic drug matrix comparator results in the intended clinical studies.

The development and validation of a method for quantifying olanzapine in human plasma by liquid chromatography tandem mass spectrometry and its application in a pharmacokinetic study

1. A rapid method using liquid chromatography tandem mass spectrometry for the quantification of olanzapine (OLZ) in human plasma was developed and validated. Venlafaxine was used as the internal standard (IS), and the samples were extracted from 400-μL human plasma with methyl tert-butyl ether for liquid-liquid extraction. 2. Chromatography was performed using an ACE C18, 125 × 4.6-mm i.d., 5-μm column. The mobile phase consisted of water with 0.1% formic acid for solvent A and acetonitrile with 0.1% formic acid for solvent B (50 : 50 v/v) in isocratic mode. The flow rate was 1.2 mL/min. The retention times for OLZ and the IS were 0.78 and 1.04 min, respectively. Tandem mass spectrometry operating in positive electrospray ionization mode with multiple reaction monitoring was used to detect OLZ and the IS (m/z: 313.1 > 256.1 and 278.1 > 260.2, respectively). 3. No significant matrix effects were observed on OLZ and the IS retention times, and the mean recovery of OLZ was 90.08%. The assay was linear in the concentration range of 1-20 ng/mL (R(2) = 0.9976). The intra- and inter-day precision were < 11.60% and the accuracy was < 1.66%. 4. This validated method was successfully applied to a pharmacokinetic study in which 10-mg OLZ tablets were administered to healthy volunteers and their plasma OLZ levels were monitored over time. The tests showed that the OLZ test and reference drug (Zyprexa(®)) were bioequivalent, as 90% of the confidence intervals were within the 80-125% interval proposed by regulatory agencies.

Liquid chromatography tandem mass spectrometry in the clinical laboratory

Clinical laboratory medicine has seen the introduction and evolution of liquid chromatography tandem mass spectrometry in routine clinical laboratories over the last 10–15 years. There still exists a wide diversity of assays from very esoteric and highly specialist manual assays to more simplified kit-based assays. The technology is not static as manufacturers are continually making improvements. Mass spectrometry is now commonly used in several areas of diagnostics including therapeutic drug monitoring, toxicology, endocrinology, paediatrics and microbiology. Some of the most high throughput analyses or common analytes include vitamin D, immunosuppressant monitoring, androgen measurement and newborn screening. It also offers flexibility for the measurement of analytes in a variety of different matrices which would prove difficult with immunoassays. Unlike immunoassays or high-pressure liquid chromatography assays using ultraviolet or fluorescence detection, mass spectrometry offers better specificity and reduced interferences if attention is paid to potential isobaric compounds. Furthermore, multiplexing, which enables multiple analytes to be measured with the same volume of serum is advantageous, and the requirement for large sample volumes is decreasing as instrument sensitivity increases. There are many emerging applications in the literature. Using mass spectrometry to identify novel isoforms or modified peptides is possible as is quantification of proteins and peptides, with or without protein digests. Future developments by the manufacturers may also include mechanisms to improve the throughput of samples and strategies to decrease the level of skill required by the operators.

A critical review of microextraction by packed sorbent as a sample preparation approach in drug bioanalysis

Sample preparation is widely accepted as the most labor-intensive and error-prone part of the bioanalytical process. The recent advances in this field have been focused on the miniaturization and integration of sample preparation online with analytical instrumentation, in order to reduce laboratory workload and increase analytical performance. From this perspective, microextraction by packed sorbent (MEPS) has emerged in the last few years as a powerful sample preparation approach suitable to be easily automated with liquid and gas chromatographic systems applied in a variety of bioanalytical areas (pharmaceutical, clinical, toxicological, environmental and food research). This paper aims to provide an overview and a critical discussion of recent bioanalytical methods reported in literature based on MEPS, with special emphasis on those developed for the quantification of therapeutic drugs and/or metabolites in biological samples. The advantages and some limitations of MEPS, as well as its comparison with other extraction techniques, are also addressed herein.

Development and validation of a sensitive and robust LC-MS/MS with electrospray ionization method for simultaneous quantitation of quetiapine and its active metabolite norquetiapine in human plasma

BACKGROUND

Quetiapine is an atypical antipsychotic agent for the treatment of schizophrenia, acute mania, and acute bipolar depression. The antidepressive response is considered to be mediated by the metabolite norquetiapine (N-desalkylquetiapine), and the aim of this study was to develop an LC-MS/MS method to measure concentrations of these compounds in human plasma.

METHODS

Following one step liquid-liquid extraction, the analytes were separated using an isocratic mobile phase on a Sunfire C18 column (50mm×2.1mm, 5μm). The retention times were 2.12, 2.24, 2.12 and 2.19min for quetiapine, norquetiapine and their respective stable labeled internal standards, respectively. Cycle time was 4min. Selected reaction monitoring (SRM) in positive ion mode was used for quantitation.

RESULTS

The present method exhibited a linear dynamic range of 0.5-500ng/ml for quetiapine and 0.6-600ng/ml for norquetiapine. The applicable range was extended by dilution up to 5-fold with blank matrix. The accuracy and precision for quetiapine were <103.0% and 8.8%, for norquetiapine were <108.8% and 11.1%, respectively.

CONCLUSIONS

A rapid, sensitive, and robust LC-MS/MS method for quantifying quetiapine and its metabolite norquetiapine levels in human plasma was validated and successfully applied to samples from schizophrenic patients in clinical pharmacokinetics studies.

Validation of Quetiapine Fumarate in Pharmaceutical Dosage by Reverse-Phase HPLC with Internal Standard Method

A rapid, specific, and accurate isocratic HPLC method was developed and validated for the assay of quetiapine fumarate in pharmaceutical dosage forms. The assay involved an isocratic-elution of quetiapine fumarate in Grace C18 column using mobile-phase composition of 0.1% ortho phosphoric acid with triethyl amine as modifier buffer and acetonitrile in the ratio of 50 : 50 (v/v).The wavelength of detection is 294 nm. The method showed good linearity in the range of 2.0–50.2 × 10−3 g/Lt. The runtime of the method is 5 mins. The developed method was applied to directly and easily analyse of the pharmaceutical tablet preparations. The percentage recoveries were near 100% for given methods. The method was completely validated and proven to be rugged. The excipients did not interfere in the analysis. The results showed that this method can be used for rapid determination of quetiapine fumarate in pharmaceutical tablet with precision, accuracy, and specificity.

A validated UHPLC–diode array detector method for the bioanalysis of atypical antipsychotics in whole blood, urine and cerebrospinal fluid following SPE

Background: Risperidone, quetiapine, amisulpride and aripiprazole are atypical antipsychotics increasingly prescribed in Greece. Results: We have developed and validated a UHPLC–diode array detector method for the determination of these drugs in whole blood, urine and cerebrospinal fluid, following SPE. The separation was achieved within 7 min. Validation was performed in terms of linearity, selectivity, accuracy, precision and stability. Following validation, the method was applied to post-mortem blood, urine and cerebrospinal fluid samples. Conclusion: The method proved fast and simple for the determination of four atypical antipsychotic drugs in whole blood, urine and cerebrospinal fluid. To the best of our knowledge, this is the only available method for the simultaneous determination of these drugs in cerebrospinal fluid.

Atypical antipsychotics: trends in analysis and sample preparation of various biological samples

Atypical antipsychotics are increasingly popular and increasingly prescribed. In some countries, they can even be obtained over-the-counter, without a prescription, making their abuse quite easy. Although atypical antipsychotics are thought to be safer than typical antipsychotics, they still have severe side effects. Intoxications are not rare and some of them have a fatal outcome. Drug interactions involving atypical antipsychotics complicate patient management in clinical settings and the determination of the cause of death in fatalities. In view of the above, analytical strategies that can efficiently isolate atypical antipsychotics from a variety of biological samples and quantify them accurately, sensitively and reliably, are of utmost importance both for the clinical, as well as for the forensic toxicologist. In this review, we will present and discuss novel analytical strategies that have been developed from 2004 to the present day for the determination of atypical antipsychotics in various biological samples.