Active Metabolite 9-hydroxyrisperidone Research Articles

Dissolving microarray patches for transdermal delivery of risperidone for schizophrenia management

Schizophrenia is a psychiatric disorder that results from abnormal levels of neurotransmitters in the brain. Risperidone (RIS) is a common drug prescribed for the treatment of schizophrenia. RIS is a hydrophobic drug that is typically administered orally or intramuscularly. Transdermal drug delivery (TDD) could potentially improve the delivery of RIS. This study focused on the development of RIS nanocrystals (NCs), for the first time, which were incorporated into dissolving microneedle array patches (DMAPs) to facilitate the drug delivery of RIS. RIS NCs were formulated via wet-media milling technique using poly(vinylalcohol) (PVA) as a stabiliser. NCs with particle size of 300 nm were produced and showed an enhanced release profile up to 80 % over 28 days. Ex vivo results showed that 1.16 ± 0.04 mg of RIS was delivered to both the receiver compartment and full-thickness skin from NCs loaded DMAPs compared to 0.75 ± 0.07 mg from bulk RIS DMAPs. In an in vivo study conducted using female Sprague Dawley rats, both RIS and its active metabolite 9-hydroxyrisperidone (9-OH-RIS) were detected in plasma samples for 5 days. In comparison with the oral group, DMAPs improved the overall pharmacokinetic profile in plasma with a ∼ 15 folds higher area under the curve (AUC) value. This work has represented the novel delivery of the antipsychotic drug, RIS, through microneedles. It also offers substantial evidence to support the broader application of MAPs for the transdermal delivery of poorly water-soluble drugs.

Inflammation affects the pharmacokinetics of risperidone: Does the dose need to be adjusted during the acute-phase reaction?

BackgroundSeveral studies have indicated that the plasma concentration of risperidone increases 3–5-fold during the acute-phase reaction (APR) of inflammation or infection. Psychiatric symptoms are present or deteriorate when the dose is lowered; thus, the complex effects of inflammation on the pharmacokinetics of risperidone need to be examined. MethodsWe established a APR model in rabbits induced by lipopolysaccharide (LPS) and studied the effect of APR on pharmacokinetics, distribution and disposition of risperidone in vivo and in vitro. ResultsFollowing intramuscular administration, the plasma exposures for risperidone and its active metabolite (9-hydroxyrisperidone) were increased approximately 6-fold on day 2 of inflammation. The exposure values did not change between day 2 and 5 of inflammation, nor did the metabolite-to-parent ratio before and during inflammation. Following oral administration, the increase of risperidone exposure was twice as high as that following intramuscular administration during APR. However, the concentration of risperidone and 9-hydroxyrisperidone in brain tissue was similar between the inflammatory and control groups. Moreover, the plasma protein binding (PPB) of risperidone and 9-hydroxyrisperidone associated with inflammation were all increased to >99 %. In addition, risperidone and 9-hydroxyrisperidone were not substrates of the key transporters, OATP1B3, OCT2, OAT3, MATE-1, or MATE-2 K. The expression of progesterone X receptor and P-glycoprotein was inhibited by LPS. ConclusionDuring APR, reduced expression of P-glycoprotein and increased PPB were responsible for increased exposure in plasma, while maintaining stable concentrations in the brain, and risperidone does not need to be dose-adjusted so as to achieve psychopharmacological outcomes.

Factors influencing concentrations of risperidone and 9-hydroxyrisperidone in psychiatric outpatients taking immediate-release formulations of risperidone.

To analyze the factors affecting the concentrations of the active moiety of risperidone (RIS) and its active metabolite 9-hydroxyrisperidone (9-OH-RIS) in psychiatric outpatients taking immediate-release formulations. This is a retrospective study on the therapeutic drug monitoring (TDM) data regarding RIS and 9-OH-RIS in adult psychiatric outpatients. TDM data with simultaneous RIS and 9-OH-RIS monitoring from March 2018 to February 2020 and relevant medical records (including dosage, dosage form, sex, age, diagnosis, combined medication, and comorbid disease) from 399 adult psychiatric outpatients (223 males and 176 females) were included in this study. The daily dose of RIS was 5.56±2.05mg, the concentration of total active moiety was 42.35±25.46ng/mL, and the dose-adjusted plasma concentration (C/D) of active moiety was 7.83±3.87 (ng/ml)/(mg/day). Dose, sex, and age were identified as important factors influencing concentrations of RIS and 9-OH-RIS in adult psychiatric outpatients. Individualized medication adjustments should be made according to the specific conditions of psychiatric outpatients. The findings strongly support the use of TDM to guide dosing decisions in psychiatric outpatients taking RIS.

A liquid chromatography-miniature mass spectrometry (LC-Mini MS) method for quantitative analysis of risperidone and 9-hydroxyrisperidone in plasma.

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a universal method for the quantitative analysis of small molecular drugs in therapeutic drug monitoring (TDM). Alternatively, liquid chromatography-miniature mass spectrometry (LC-Mini MS) is a simple operating technique for quantitative analysis. However, the wide chromatographic peaks and long retention times of TDM samples using the LC-Mini MS system deteriorated the accuracy and efficiency of quantitative analysis. Here, an optimized electrospray ionization (ESI) interface setup with a splitter valve and a capillary needle (I.D. 30 μm and O.D. 150 μm) of the LC-Mini MS system was acquired. The chromatographic peaks were narrower and smoother and the retention time was shorter for TDM compounds. Furthermore, a quantitative analysis method for risperidone and the active metabolite 9-hydroxyrisperidone in plasma was developed based on this optimal LC-Mini MS setup. The results showed that the calibration curves of risperidone and 9-hydroxyrisperidone had good linear ranges of 2-100 ng mL-1 (R2 = 0.9931) and 2-100 ng mL-1 (R2 = 0.9915), respectively. Finally, the matrix effects, recoveries and stability of risperidone and 9-hydroxyrisperidone samples were analyzed. The results satisfied the requirements of quantitative validation in routine TDM procedures.

Therapeutic drug monitoring of risperidone and its active metabolite 9-hydroxyrisperidone in the treatment of schizophrenia

To conduct a routine therapeutic drug monitoring (TDM) and analyze its results for the optimization of pharmacotherapy. Fifty-six inpatients (in total 68 samples) with various forms of schizophrenia were enrolled. High performance liquid chromatography with mass-spectrometric detection was used for quantitative determination of risperidone and 9-hydroxyrisperidone in the serum. Concentrations of risperidone and 9-hydroxyrisperidone were correlated with drug dose. Total concentrations in the blood at doses from 2 to 8 mg per day were distributed as follows: 44.1% were in the therapeutic, 29.4% in sub-therapeutic (<20 ng/mL) and 26.5% in conditionally toxic range (>60 ng/mL). Concentrations of risperidone and 9-hydroxyrisperidone did not follow the normal distribution. The results showed that monitoring of the total concentration of risperidone and its metabolite 9-hydroxyrisperidone was an effective tool for testing and quality control for the purpose of individualization of pharmacotherapy.

Validation of a dried blood spot method for therapeutic drug monitoring of citalopram, mirtazapine and risperidone and its active metabolite 9-hydroxyrisperidone using HPLC–MS

Citalopram, mirtazapine and risperidone are frequently prescribed for psychiatric illnesses such as depression and psychosis or for aggressive behavior in elderly patients with dementia. The plasma concentrations vary greatly between patients, especially in elderly patients. Thus, therapeutic drug monitoring (TDM) increases the safety of antipsychotic treatment and a more rapid response to treatment may be achieved. To facilitate TDM, the objectives of this study were to develop and validate a reliable dried blood spot method to simultaneously quantify citalopram, mirtazapine and risperidone including its active metabolite 9-hydroxyrisperidone. The blood punches were extracted by methanol using an ultrasonic bath, purified by liquid–liquid extraction and analyzed by liquid chromatography/mass spectrometry (LC–MS). All acceptance criteria of the EMA and FDA guidelines for method validation were fulfilled. Linearity was shown over the range of 2.5–300μg/L for all substances. The analytes were stable for at least one month at all investigated storage conditions, including storing at room temperature exposed to light. Retrieving capillary blood by finger-pricking the assay was successfully applied in elderly patients. Venous serum samples were drawn simultaneously to compare capillary blood with serum concentrations. Given the validated results and the calculated capillary blood:serum ratio, the studied dried blood spot method offers an excellent application in TDM and can be applied in ambulatory care.

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 Cmax, tmax, 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.

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.

Effect of smoking on risperidone pharmacokinetics – A multifactorial approach to better predict the influence on drug metabolism

PurposeTo disentangle an association between tobacco smoking, smoking habits and pharmacokinetic patterns such as plasma concentrations of risperidone (RIS), its active metabolite 9-hydroxyrisperidone (9-OH-RIS) and the active moiety, AM, (RIS+9-OH-RIS) in a naturalistic sample. MethodsPlasma concentrations, dose adjusted plasma concentrations (C/D) of RIS, 9-OH-RIS and AM in patients out of a therapeutic drug monitoring (TDM) database were compared between smokers (n=401) and non-smokers (n=292). ResultsDaily dosage of risperidone differed significantly with smokers receiving higher doses than patients in the control group (p=0.001). No differences were detected in plasma concentrations of the active moiety, RIS and 9-OH-RIS (p=0.8 for AM, p=0.646 for RIS and p=0.538 for 9-OH-RIS). However, dose corrected concentrations (C/D) of metabolite (C/D 9-OH-RIS) and active moiety (C/D AM) differed between significantly between groups (p=0.002 and p=0.007). After stratifying smokers to a group of moderate smokers (<20cigarettes/day) (RS1, n=109) and a group of heavy smokers (≥20cigarettes/day) (RS2, n=135), the comparison between non-smokers and both groups only showed lower values of C/D for 9-OH-RIS (p=0.011) for the group of moderate smokers while other pharmacokinetic parameters did not differ. ConclusionsApart from the well-known induction of CYP1A2 activity by polycyclic aromatic hydrocarbons, smoking might exert an effect on other CYP isoenzymes as well. A possible interpretation proposes a slight inducing effect of smoking on risperidone metabolism most likely via CYP3A4.

Clinical response in a risperidone-medicated naturalistic sample: patients' characteristics and dose-dependent pharmacokinetic patterns.

The purpose of this study was to disentangle an association between plasma concentrations of risperidone (RIS), its active metabolite 9-hydroxyrisperidone (9-OH-RIS) and the active moiety, AM (RIS+9-OH-RIS), and clinical response in a naturalistic sample. Plasma concentrations of RIS, 9-OH-RIS and AM in patients out of a therapeutic drug monitoring (TDM) database were compared between responders (n=64) and non-responders (n=526) using the Clinical Global Impressions (CGI) Scale. Daily dosage of risperidone did not differ between responders and non-responders. Differences for active moiety plasma levels between the two groups did not reach statistical significance. However, responders showed lower plasma concentrations of the parent compound RIS as well as lower metabolic ratios RIS/9-OH-RIS than non-responders (p=0.017 and p=0.034). These differences did not remain after controlling for age and baseline symptoms. Furthermore, the cohort was split into two subgroups based on the daily dosage: patients under high (≥6mg/day) (R H, n=187) and patients under lower dosages (<6mg) (R L, n=403) of risperidone. Differences between responders and non-responders after controlling for demographic and clinical characteristics remained only for plasma concentrations of active moiety in the lower-dose medicated groups; non-responders showed higher active moiety plasma concentrations than responders. Understanding the mechanisms involved and factors associated with the clinical response in patients medicated with antipsychotics is of great interest. Our data imply that clinical response to an antipsychotic treatment cannot be attributed to a single pharmacokinetic pattern. It seems to be rather a complex patchwork of influencing factors such as demographic and clinical characteristics as well as the metabolizer status as surrogate of CYP activity. It seems that the ratio between RIS and 9-OH-RIS may play a crucial role in mediating the clinical effect.

Pharmacokinetic patterns of risperidone-associated adverse drug reactions.

The aim of the study was to investigate a correlation between plasma concentrations of risperidone (RIS), its active metabolite 9-hydroxyrisperidone (9-OH-RIS) and the active moiety (AM) (RIS + 9-OH-RIS), and adverse drug reactions (ADRs) in a naturalistic sample. Plasma concentrations of RIS, 9-OH-RIS, and AM in patients out of a therapeutic drug monitoring (TDM) database complaining ADRs were categorized according to the Udvalg for Kliniske Undersogelser side effect rating scales (UKU) (n=97) and compared to patients without ADRs (n=398). Patients in the ADR group received a significantly lower daily dosage of risperidone (trimmed mean 3.64mg/day) than patients without ADRs (4.40mg/day). No differences were found for active moiety plasma concentrations between the groups (p=0.454). Differences were detected only in the case of dose-adjusted plasma concentration values (concentration-by-dose, C/D) for 9-OH-RIS, being higher in patients reporting ADRs (4.78ng/mL/mg) than in patients without ADRs (4.3ng/mL/mg) (p=0.037 for Mann-Whitney U test). Note that differences for non-adjusted 9-OH-RIS plasma levels between groups failed to reach significance (p=0.697). Our findings are consistent with previous data supporting a prominent role of 9-hydroxyrisperidone, but not of risperidone with regard to ADRs. When studying the various subgroups of reported ADRs separately, the size of these subsamples offers some plausible limitations by reducing the power of the analysis.

Postmortem Femoral Blood Concentrations of Risperidone

Postmortem femoral blood concentrations of the antipsychotic drug risperidone and the active metabolite 9-hydroxyrisperidone were determined by an achiral LC-MS/MS method in 38 cases. The cause of death was classified as unrelated to risperidone in 30 cases, in which the sum of the concentration of the drug and metabolite ranged from below the limit of quantification to 0.058 mg/kg (median 0.0098 mg/kg). This concentration range, which largely corresponds to published in vivo plasmalevels under therapy, may serve as a reference for judgment of postmortem cases involving risperidone. In one case, risperidone was judged to be a contributing factor to death, and the sum of concentrations was 0.29 mg/kg. This concentration is of the same order of magnitude as observed for plasma levels in clinical intoxication cases. For the remaining seven cases, the cause of death was unclear. The measurements observed here do not suggest that risperidone is subject to major postmortem redistribution.

Solid phase microextraction and LC–MS/MS for the determination of paliperidone after stereoselective fungal biotransformation of risperidone

The present work describes for the first time the use of SPME coupled to LC–MS/MS employing the polar organic mode in a stereoselective fungal biotransformation study to investigate the fungi ability to biotransform the drug risperidone into its chiral and active metabolite 9-hydroxyrisperidone (9-RispOH). The chromatographic separation was performed on a Chiralcel OJ-H column using methanol:ethanol (50:50, v/v) plus 0.2% triethylamine as the mobile phase at a flow rate of 0.8mLmin−1. The SPME process was performed using a C18 fiber, 30min of extraction time and 5min of desorption time in the mobile phase. The method was completely validated and all parameters were in agreement with the literature recommendations. The Cunninghamella echinulata fungus was able to biotransform risperidone into the active metabolite, (+)-9-RispOH, resulting in 100% of enantiomeric excess. The Cunninghamella elegans fungus was also able to stereoselectively biotransform risperidone into (+)- and (−)-9-RispOH enantiomers at different rates.

Blonanserin, a novel atypical antipsychotic agent not actively transported as substrate by P-glycoprotein

Although blonanserin, a novel atypical antipsychotic agent with dopamine D(2)/serotonin 5-HT(2A) antagonistic properties, displays good brain distribution, the mechanism of this distribution has not been clarified. P-glycoprotein [(P-gp) or multidrug resistance protein 1 (MDR1)] is an efflux transporter expressed in the brain and plays an important role in limiting drug entry into the central nervous system (CNS). In particular, P-gp can affect the pharmacokinetics and efficacy of antipsychotics, and exacerbate or soothe their adverse effects. In this study, we conducted in vitro and in vivo experiments to determine whether blonanserin is a P-gp substrate. Risperidone and its active metabolite 9-hydroxyrisperidone, both of which are P-gp substrates, were used as reference drugs. Affinity of blonanserin, risperidone, and 9-hydroxyrisperidone for P-gp was evaluated by in vitro transcellular transport across LLC-PK1, human MDR1 cDNA-transfected LLC-PK1 (LLC-MDR1), and mouse Mdr1a cDNA-transfected LLC-PK1 (LLC-Mdr1a). In addition, pharmacokinetic parameters in the brain and plasma (B/P ratio) of test compounds were measured in mdr1a/1b knockout (KO) and wild-type (WT) mice. The results of in vitro experiments revealed that P-gp does not actively transport blonanserin as a substrate in humans or mice. In addition, blonanserin displayed comparable B/P ratios in KO and WT mice, whereas B/P ratios of risperidone and 9-hydroxyrisperidone differed markedly in these animals. Our results indicate that blonanserin is not a P-gp substrate and therefore its brain distribution is unlikely to be affected by this transporter.

Comparative pharmacokinetics and bioequivalence of two tablet formulations of 2 mg risperidone in healthy Thai male volunteers

Risperidone is an atypical antipsychotic drug with potent serotonin and moderate dopamine antagonistic properties. It possesses good bioavailability following oral administration. Risperidone is primarily converted by the cytochrome P450 2D6 (CYP2D6) and 3A4 (CYP3A4) enzymes to 9-hydroxyrisperidone, its active metabolite with equivalent potency to the parent compound. This study aimed to compare the pharmacokinetics and determine bioequivalence of two risperidone immediate release oral tablets, a test formulation (Risperidone GPO® or "Test") and a reference formulation (Risperdal® or "Reference"). A single-dose, randomized, fasting, 2-period, 2-sequence, crossover study design with a 2-week washout period was conducted in 23 healthy Thai male volunteers. Blood samples were collected predose and at 0.25, 0.5, 0.75, 1, 1.5, 2, 3, 4, 5, 6, 8, 12, 24, 36, 48, 72 and 96 h following an oral administration of 2 mg risperidone. The plasma concentrations of risperidone and 9-hydroxyrisperidone were determined by using a validated HPLC method. Pharmacokinetic parameters of Test and Reference were obtained by noncompartmental analysis. The 90% confidence intervals for Test/Reference ratios of the pharmacokinetic parameters (Cmax, AUC0-t and AUC0-∞) of both risperidone and its active metabolite (9-hydroxyrisperidone) fell within the acceptable bioequivalence range (80 - 125%) according to ASEAN guideline. The two risperidone formulations are bioequivalent. The test formulation may be used for generic substitution where applicable.

Analysis of risperidone and 9-hydroxyrisperidone in human plasma, urine and saliva by MEPS-LC-UV

Risperidone is currently one of the most frequently prescribed atypical antipsychotic drugs; its main active metabolite 9-hydroxyrisperidone contributes significantly to the therapeutic effects observed. An original analytical method is presented for the simultaneous analysis of risperidone and the metabolite in plasma, urine and saliva by high-performance liquid chromatography coupled to an original sample pre-treatment procedure based on micro-extraction by packed sorbent (MEPS). The assays were carried out using a C8 reversed-phase column and a mobile phase composed of 73% (v/v) acidic phosphate buffer (30mM, pH 3.0) containing 0.23% triethylamine and 27% (v/v) acetonitrile. The UV detector was set at 238nm and diphenhydramine was used as the internal standard. The sample pre-treatment by MEPS was carried out on a C8 sorbent. The extraction yields values were higher than 92% for risperidone and 90% for 9-hydroxyrisperidone, with RSD for precision always lower than 7.9% for both analytes. Limit of quantification values in the different matrices were 4ng/mL or lower for risperidone and 6ng/mL or lower for the metabolite. The method was successfully applied to plasma, urine and saliva samples from psychotic patients undergoing therapy with risperidone, with satisfactory accuracy results (recovery>89%) and no interference from other drugs. Thus, the method seems to be suitable for the therapeutic drug monitoring of schizophrenic patients using the three different biological matrices plasma, urine and saliva.

Induction of Drug Transporters Alters Disposition of Risperidone - A Study in Mice.

Pharmacokinetic interactions, e.g. modulation of drug transporters like P-glycoprotein at the blood-brain barrier, can be a reason for treatment non-response. This study focuses on the influence of induction of drug transporters on the disposition of the antipsychotic drugs risperidone and 9-hydroxyrisperidone. Brain and serum concentrations of risperidone and its active metabolite 9-hydroxyrisperidone, which are known P-glycoprotein substrates, were measured after drug transporter induction with rifampicin, dexamethasone or 5-pregnene-3beta-ol-20-on-16alpha-carbonitrile using high performance liquid chromatography. Disposition of risperidone and 9-hydroxyrisperidone was dramatically decreased in mouse brain and serum after drug transporter induction. The metabolism of risperidone was also affected.

Analysis of risperidone and its metabolite in plasma and saliva by LC with coulometric detection and a novel MEPS procedure

A new analytical method, based on the use of liquid chromatography with coulometric detection, has been developed and applied to quantify risperidone and its main active metabolite 9-hydroxyrisperidone in human plasma and saliva. The analytes were separated on a reversed phase C18 column, using a mobile phase composed of acetonitrile (26%) and a pH 6.5 phosphate buffer (74%). Pipamperone was used as the internal standard. A high sensitivity coulometric detection analytical cell containing two flow-through working electrodes was used: electrode 1 was set at +0.500V and electrode 2 at +0.700V. The detector response was linear over a plasma and saliva concentration range of 0.5-50.0ngmL(-1) for risperidone and 0.5-100.0ngmL(-1) for 9-hydroxyrisperidone. The limit of quantitation and the limit of detection for risperidone and 9-hydroxyrisperidone were 0.5ngmL(-1) and 0.17ngmL(-1), respectively. A novel clean-up procedure of biological samples was developed using the microextraction by packed sorbent technique, which gave good extraction yield for both the analytes, with absolute recovery values higher than 90.1%. The intra-day and the inter-day precision results, expressed by relative standard deviation values, were lower than 5.8%. Accuracy and selectivity assays were also satisfactory. The validated method has been successfully applied to the analysis of risperidone and 9-hydroxyrisperidone in plasma and saliva of psychiatric patients undergoing therapy with risperidone.

EFFECT OF ZIPRASIDONE DOSE ON RATES OF MEDICATION DISCONTINUATION IN ACUTE SCHIZOPHRENIA OR SCHIZOAFFECTIVE DISORDER

A significant percentage of psychiatric patients who are treated with antipsychotics are treated with more than one antipsychotic drug in the clinic. Thus, it is advantageous to use a rapid and reliable assay that is suitable for determination of multiple antipsychotic drugs in plasma in a single run. A simple and sensitive HPLC-UV method was developed and validated for simultaneous quantification of olanzapine, haloperidol, chlorpromazine, ziprasidone, risperidone and its active metabolite 9-hydroxyrisperidone in rat plasma using imipramine as an internal standard (I.S.). The analytes were extracted from rat plasma using a single step liquid–liquid acid solution back extraction technique with wash procedure, which provided the very clear baseline for blank plasma extraction. The compounds were separated on an Agilent Eclipse XDB C8 (150 mm × 4.6 mm i.d., 5 μm) column using a mobile phase of acetonitrile/30 mM ammonium acetate including 0.05% triethylamine (pH 5.86 adjusted with acetic acid) with gradient elution. All of the analytes were monitored using UV detection. The method was validated and the linearity, lower limit of quantitation (LLOQ), precision, accuracy, recoveries, selectivity and stability were determined. The LLOQ was 2.0 ng/ml and correlation coefficient (R2) values for the linear range of 2.0–500.0 ng/ml were 0.998 or greater for all the analytes. The precision and accuracy for intra-day and inter-day were better than 7.44%. The recovery was above 74.8% for all of the analytes. This validated method has been successfully used to quantify the plasma concentration of the analytes for pharmacological and toxicological studies following chronic treatment with antipsychotic drugs in the rat.

Validated LC–MS/MS methods for the determination of risperidone and the enantiomers of 9-hydroxyrisperidone in human plasma and urine

Two liquid chromatography coupled to tandem mass spectrometry (LC–MS/MS) methods are described, one for the quantitative determination of risperidone and the enantiomers of its active metabolite 9-hydroxyrisperidone (paliperidone) in human plasma and the other for the determination of the enantiomers of 9-hydroxyrisperidone in human urine. The plasma method is based on solid-phase extraction of 200 μl of sample on a mixed-mode sorbent, followed by separation on a cellulose-based LC column with a 13.5-min mobile phase gradient of hexane, isopropanol and ethanol. After post-column addition of 10 mM ammonium acetate in ethanol/water, detection takes place by ion-spray tandem mass spectrometry in the positive ion mode. Method validation results show that the method is sufficiently selective towards the enantiomers of 7-hydroxyrisperidone and capable of quantifying the analytes with good precision and accuracy in the concentration range of 0.2–100 ng/ml. An accelerated (run time of 4.3 min) and equally valid method for the enantiomers of 9-hydroxyrisperidone alone in plasma is obtained by increasing the mobile phase flow-rate from 1.0 to 2.0 ml/min and slightly adapting the gradient conditions. The urine method is based on the same solid-phase extraction and chromatographic approach as the accelerated plasma method. Using 100 μl of sample, (+)- and (−)-9-hydroxyrisperidone can be quantified in the concentration range 1–2000 ng/ml. The accelerated method for plasma and the method for urine can be used only when paliperidone is administered instead of risperidone, as there is insufficient separation of the 9-hydroxy enantiomers from the 7-hydroxy enantiomers, the latter ones being present only after risperidone administration.