Simultaneous determination of risperidone and 9-hydroxyrisperidone enantiomers in human blood plasma by liquid chromatography with electrochemical detection

Guava-fruit based synthesis of carbon quantum dots for spectrofluorometric quantitative analysis of risperidone in spiked human plasma and pharmaceutical dosage forms

Autism is one of the most pressing issues facing the international community in recent years, particularly in Middle Eastern countries. Risperidone is a selective serotonin type 2 and dopamine type 2 receptor antagonist. It is the most administered antipsychotic medication in children with autism-related behavioral disorders. Therapeutic monitoring of risperidone may improve safety and efficacy in autistic individuals. The main objective of this work was to develop a highly sensitive green fitted method for the determination of risperidone in the plasma matrix and pharmaceutical dosage forms. Novel water-soluble N-carbon quantum dots were synthesized from guava fruit, a natural green precursor, and used for determination of risperidone based on quenching fluorescence spectroscopy phenomena. The synthesized dots were characterized by transmission electron microscopy and Fourier transform infrared spectroscopy. The synthesized N-carbon quantum dots exhibited aquantum yield of 26.12% and showed a strong emission fluorescence peak at 475 nm when excited at 380 nm. The fluorescence intensity of the N-carbon quantum dots decreased with increasing risperidone concentration, indicating that the fluorescence quenching was concentration dependent. The presented method was carefully optimized and validated according to the guidelines of ICH, and it demonstrated good linearity in a concentration range of 5-150 ng mL-1. With a LOD of 1.379 ng mL-1 and a LOQ of 4.108 ng mL-1, the technique was extremely sensitive. Due to the high sensitivity of the proposed method, it could be effectively used for the determination of risperidone in the plasma matrix. The proposed method was compared with the previously reported HPLC method in terms of sensitivity and green chemistry metrics. The proposed method proved to be more sensitive and compatible with the principles of green analytical chemistry.

Chemometrics-assisted Spectrophotometric Method for Simultaneous Estimation of Antipsychotic Drugs in Biological Fluid

Background:

Haloperidol (HP) and Risperidone (RIS) are antipsychotic drugs and the simultaneous determination of these drugs is important. Estimation of HP and RIS alone or in combination with other drugs has been performed in a variety of ways.

Objective:

The aim of this paper was to propose a rapid, simple, accurate, and robust method for the simultaneous determination of HP and RIS using Artificial Neural Networks (ANNs), Partial Least Squares (PLS), and Principal Component Regression (PCR) methods along with spectrophotometry technique.

Methods:

The simultaneous spectrophotometric determination of HP and RIS in synthetic mixtures and biological fluid was performed by applying ANNs Containing Feed-forward Backpropagation (FFBP) and Radial Basis Function (RBF) networks as intelligent methods, as well as PLS, and principal component regression PCR as multivariate calibration methods. The Levenberg- Marquardt (LM), Scaled Conjugate Gradient (SCG), and Resilient Back-propagation (RP) algorithms with different layers and neurons were used in FFBP network and obtained results were compared with each other.

Results:

Among various algorithms of the FFBP network, the LM algorithm was selected as the best model with a lower Mean Square Error (MSE). MSE of the RBF model was 1.46×10-25 and 1.62×10-23 for HP and RIS, respectively. On the other hand, the mean recovery of PLS and PCR was 99.91%, 100.01% and 98.60%, 101.90% for HP and RIS, respectively.

Conclusion:

The proposed models and High-Performance Liquid Chromatography (HPLC) as a reference method were compared with each other by one-way Analysis of Variance (ANOVA) test at the 95 % confidence level for the urine sample. It was observed that the developed methods presented comparable results for the simultaneous determination of HP and RIS.

Field-amplified sample injection in capillary zone electrophoresis for the pharmacokinetic research of trace risperidone and its major metabolite 9-hydroxyrisperidone in beagle dogs

This article describes a method for the simultaneous quantitation of risperidone and its major metabolite, 9-hydroxyrisperidone, in beagle dog plasma by field-amplified sample injection in capillary zone electrophoresis. The separation was carried out at 25°C in a 48 cm × 75 µm fused-silica capillary with an applied voltage of 20 kV using 60 mM NaH₂ PO₄ buffer (pH 3.6). The detection wavelength was 280 nm. Clean-up and preconcentration of plasma samples were conducted by 96-well formatted liquid-liquid extraction. In this study, this stacking technique provided a sensitivity enhancement of approximately 158 to 188 fold compared with the same sample without stacking. The method was suitably validated with respect to stability, specificity, linearity, lower limit of quantitation, accuracy, precision, and extraction recovery. Calibration curves exhibited good linearity (r²  > 0.995) over a wide concentration range of 2.5 to 200 ng/mL for both risperidone and 9-hydroxyrisperidone. The intra- and interday precisions at the three quality control levels were less than 11.40%. The intra- and interday accuracies ranged from 87.90 to 107.17% for risperidone and from 88.43 to 105.92% for 9-hydroxyrisperidone. All validation data were within the required limits. In conclusion, the method developed was successfully applied to pharmacokinetic studies of risperidone and 9-hydroxyrisperidone in beagle dogs.

Enantioselective supercritical fluid chromatography–tandem mass spectrometry method for simultaneous estimation of risperidone and its 9-hydroxyl metabolites in rat plasma

Aim: Objective of the current work was to develop a ‘green chemistry’ compliant selective and sensitive supercritical fluid chromatography–tandem mass spectrometry method for simultaneous estimation of risperidone (RIS) and its chiral metabolites in rat plasma. Methodology & results: Agilent 1260 Infinity analytical supercritical fluid chromatography system resolved RIS and its chiral metabolites within runtime of 6 min using a gradient chromatography method. Using a simple protein precipitation sample preparation followed by mass spectrometric detection achieved a sensitivity of 0.92 nM (lower limit of quantification). With linearity over four log units (0.91–7500 nM), the method was found to be selective, accurate, precise and robust. Conclusion: The method was validated and was successfully applied for simultaneous estimation of RIS and 9-hydroxyrisperidone metabolites (R & S individually) after intravenous and per oral administration to rats.

UPLC-Tandem Mass Spectrometry Method for Simultaneous Determination of Fluoxetine, Risperidone, and Its Active Metabolite 9-Hydroxyrisperidone in Plasma: Application to Pharmacokinetics Study in Rats

Risperidone (RIS) is used as an antipsychotic drug alone or with other drugs, like fluoxetine (FLX). A simple method was developed and validated for the determination of both RIS and its metabolite 9-hydroxyrisperidone (9-OH-RIS), FLX, and olanzapine (OLA) as an internal standard in rat's plasma using UPLC-MS/MS. FLX, RIS, 9-OH-RIS, and OLA were purified using acetonitrile as a protein precipitating agent. Separation was performed on an ACQUITY™ "UPLC BEH™" C18 column (50 mm × 2.1 mm i.d., 1.7 μm; Waters Corp., USA). The ranges of the calibration curves were 1.0-1000.0 ng/mL for FLX and 0.2-1000.0 ng/mL for RIS and 9-OH-RIS. Linearity, recovery, precision, and stability were within the acceptable range. This method is rapid, fast, and precise for the determination of RIS and FLX in plasma and is applicable in pharmacokinetic studies.

Forced degradation studies, and effect of surfactants and titanium dioxide on the photostability of paliperidone by HPLC

Forced degradation study of paliperidone under hydrolytic, oxidative, thermal and photolytic stress conditions was conducted using HPLC. The drug was found to be labile under hydrolytic, oxidative and photolytic stress conditions; whereas, it was stable under dry heat stress conditions. Effect of anionic, cationic and non-ionic surfactants applied to the concentration exceeding critical micellar concentration on the photostability of paliperidone was also studied by exposing the samples to sunlight for 72h. Major degradation of the drug was found in presence of cationic and non-ionic surfactants. Effect of titanium dioxide on the photo-degradation of paliperidone in solution state was also studied and it was found that 53% of the drug was degraded after 72h of exposure to sunlight. A common degradation peak was observed in oxidative and TiO2 photocatalysed samples. This peak may be due to the generation of N-oxide of paliperidone. The same degradation peak was also observed in all other photostability samples. Chromatographic separation of drug and its degradation products was achieved on an Alltima C8 (250mm×4.6mm, 5μm) analytical column, using a mobile phase consisting of acetonitrile-ammonium acetate buffer with 0.2% triethylamine (pH 3.5; 20mM) (60:40, v/v) at a flow rate of 1mL/min. Quantification was performed with UV detection at 280nm. The method was validated as per ICH guidelines.

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.

Use of the Charge Transfer Reactions for the Spectrophotometric Determination of Risperidone in Pure and in Dosage Forms

The aim of study was to develop and validate two simple, sensitive, and extraction-free spectrophotometric methods for the estimation of risperidone in both pure and pharmaceutical preparations. They are based on the charge transfer complexation reactions between risperidone (RSP) as n-electron donor and p-chloranilic acid (p-CA) in method A and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in method B as π-acceptors. In method A, RSP reacts with p-CA in methanol to produce a bright pink-colored chromogen measured at 530 nm whereas, in method B, RSP reacts with DDQ in dichloromethane to form orange-colored complex with a maximum absorption at 460 nm. Beer's law was obeyed in the concentration range of 0-25 and 0-50 μg/mL with molar absorptivity of 1.29 × 10(4) and 0.48 × 10(4) L/moL/cm for RSP in methods A and B, respectively. The effects of variables such as reagents, time, and stability of the charge transfer complexes were investigated to optimize the procedures. The proposed methods have been successfully applied to the determination of RSP in pharmaceutical formulations. Results indicate that the methods are accurate, precise, and reproducible (relative standard deviation <2 %).

A stability-indicating ultra-performance liquid chromatographic method for estimation of related substances and degradants in paliperidone active pharmaceutical ingredient and its pharmaceutical dosage forms

A simple, linear gradient, rapid, precise and stability-indicating analytical method was developed for the estimation of related substances and degradants of paliperidone API and tablets. The chromatographic separations were achieved using an Acquity ultra-performance liquid chromatograph (BEH 100 mm, 2.1 mm, 1.7 µm C-18 column) employing 0.01 M potassium dihydrogen phosphate buffer (pH 2.0) as mobile phase A and acetonitrile-water (9:1) as mobile phase B. A linear gradient (mobile phase A, mobile phase B in the ratio of 84:16) with a 0.45 mL/min flow rate was chosen. All six impurities were eluted within five minutes of run time. The column temperature was maintained at 25 °C and a detector wavelength of 238 nm was employed. Paliperidone was exposed to thermal, photolytic, hydrolytic and oxidative stress conditions. The stressed samples were analyzed by the proposed method. Considerable degradation of the analyte was observed when it was subjected to oxidative conditions and impurity F was found to be the major degradant. Peak homogeneity data of paliperidone obtained by photodiode array (PDA) detection demonstrated the specificity of the method in the presence of degradants. The method was validated with respect to linearity, precision, accuracy, ruggedness, robustness, limit of detection and limit of quantification.

Novel strategies for sample preparation in forensic toxicology

This paper provides a review of novel strategies for sample preparation in forensic toxicology. The review initially outlines the principle of each technique, followed by sections addressing each class of abused drugs separately. The novel strategies currently reviewed focus on the preparation of various biological samples for the subsequent determination of opiates, benzodiazepines, amphetamines, cocaine, hallucinogens, tricyclic antidepressants, antipsychotics and cannabinoids. According to our experience, these analytes are the most frequently responsible for intoxications in Greece. The applications of techniques such as disposable pipette extraction, microextraction by packed sorbent, matrix solid-phase dispersion, solid-phase microextraction, polymer monolith microextraction, stir bar sorptive extraction and others, which are rapidly gaining acceptance in the field of toxicology, are currently reviewed.

A population pharmacokinetic evaluation of the influence of CYP2D6 genotype on risperidone metabolism in patients with acute episode of schizophrenia

The objective of this prospective study was to characterize the metabolism of risperidone to (+)- and (-)-9-hydroxyrisperidone in vivo and to evaluate the influence of CYP2D6 genotype. A population pharmacokinetic modeling approach was used to estimate the interindividual variability of the pharmacokinetic parameters in 50 hospitalized patients with acute episode of schizophrenia. CYP2D6 genotype remarkably influenced the formation clearances of the risperidone metabolites, while creatinine clearance was related to the plasma clearance of 9-hydroxyrisperidone. CYP2D6 genotype was also associated with the average plasma concentration of risperidone active moiety (a sum of all three active compounds). In comparison to the patients with CYP2D6*1/*1 genotype, average steady-state plasma concentration of risperidone active moiety was 3.3- and 1.6-fold higher in poor metabolizers (both alleles nonfunctional; CYP2D6*3 or *4) and intermediate metabolizers (one nonfunctional allele and one allele for diminished enzyme activity; CYP2D6*10 or *41), respectively. Additionally, average plasma concentration of risperidone active moiety was higher in the patients with dystonia (p=0.0066) and parkinsonism (p=0.046). The results of this study imply the potential role of CYP2D6 genotyping in personalizing risperidone therapy in patients with schizophrenia to reduce the incidence of adverse extrapyramidal symptoms.

MDR1 gene polymorphisms and response to acute risperidone treatment

Polymorphic multidrug resistant protein 1 (MDR1) transports drugs against a concentration gradient across the blood-brain barrier and reduces their accumulation in the brain. MDR1 may therefore influence antipsychotic brain availability contributing to inter-individual differences in treatment response and adverse effects, regardless of plasma concentrations. In the present study we investigated the influence of two common MDR1 polymorphisms on the improvement of psychopathological symptoms and occurrence of extrapyramidal side effects (EPS) in Slovenian schizophrenia patients acutely treated with risperidone. A total of 59 clinically well defined patients with first episode schizophrenia spectrum disorders or after tapering their maintenance treatment were genotyped for MDR1 C3435T and G2677T/A. Steady-state plasma concentrations of risperidone active moiety (sum of risperidone and the 9-hydroxyrisperidone) were determined. G2677T/A and C3435T genotypes were not associated to psychopathological symptoms, efficacy of treatment and risk for parkinsonism. Marginal associations with akathisia (p=0.039 and p=0.042, respectively) and dystonia (p=0.013 and p=0.034, respectively) were observed for both G2677T/A and C3435T genotypes. However, higher AIMS and BARS scores were observed only in heterozygous carriers of G2677T/A and C3435T polymorphisms and there was no tendency of gene-dose effect. The present study does not suggest a major influence of MDR1 G2677T/A and C3435T polymorphisms on treatment response during short-term risperidone therapy in patients with schizophrenia or schizoaffective disorder.