Detection of 4-FMC, 4-MeO-α-PVP, 4-F-α-PVP, and PV8 in blood in a forensic case using liquid chromatography-electrospray ionization linear ion trap mass spectrometry.

We present a case of fatal poisoning by 4-F-methcathinone (4-FMC; also called flephedrone), 4-methoxy-α-pyrrolidinopentiophenone (4-MeO-α-PVP), 4-fluoro-α-pyrrolidinopentiophenone (4-F-α-PVP), and α-pyrrolidinohepatanophenone (PV8). In this study, we compared the mass spectra of 4-FMC, 4-MeO-α-PVP, 4-F-α-PVP, PV8, and α-pyrrolidinohexanophenone between LC-ESI-LIT-MS and GC-EI-MS analyses. Subsequently, we applied LC-ESI-LIT-MS for detection and quantification analyses of 4-FMC, 4-MeO-α-PVP, 4-F-α-PVP, and PV8 in human authentic whole blood samples. More specific mass spectra for the target compounds were obtained with the LC-ESI-LIT-MS qualitative analyses than with the GC-EI-MS analyses, indicating that LC-ESI-LIT-MS was more suitable for the qualitative analysis of cathinones. The LC-ESI-LIT-MS validation data showed moderately good linearity and reproducibility for the compounds in the quantitative analyses at the range of 1-500 ng/mL. The detection limits of four cathinones ranged from 0.1 to 1 ng/mL. The concentrations of 4-FMC, 4-MeO-α-PVP, 4-F-α-PVP, and PV8 in heart whole blood samples were 365, 449, 145, and 218 ng/mL, respectively. Those of the 4 cathinones in femoral vein whole blood samples were 397, 383, 127, and 167 ng/mL, respectively. We can then assume that the cause of death was acute poisoning by a combination of 4-FMC, 4-MeO-α-PVP, 4-F-α-PVP, and PV8. In this article, we present a detailed LC-ESI-LIT-MS procedure for detection and quantification analyses of 4-FMC, 4-MeO-α-PVP, 4-F-α-PVP, and PV8 in authentic human whole blood samples.

Method development and validation for simultaneous determination of ebastine and its active metabolite carebastine in human plasma by liquid chromatography-tandem mass spectrometry and its application to a clinical pharmacokinetic study in healthy Chinese volunteers.

A simple LC-tandem mass spectrometry (MS/MS) method to determine ebastine and carebastine (active metabolite) in human plasma was developed and validated. Analytes and internal standards were precipitated by protein precipitation and separated on Synergi Hydro-RP 80A column (4 µm, 50 mm × 2.0 mm; Phenomenex) by gradient elution with mobile phase A comprising 0.1% formic acid in 5 mm ammonium acetate (NH4 Ac) and B comprising 100% methanol at a flow rate 0.4 mL/min. Ions were detected in positive multiple reaction monitoring mode, and they exhibited linearity over concentration range 0.01-8.0 and 1.00-300 ng/mL for ebastine and carebastine, respectively. A clinical pharmacokinetic study was conducted in healthy Chinese volunteers under fasting and fed conditions after a single oral administration of 10 mg ebastine. The maximum plasma concentration (Cmax ), time to Cmax (Tmax ) and elimination half-life for ebastine were 0.679 ± 0.762 ng/mL, 1.67 ± 1.43 h and 7.86 ± 6.18 h, respectively, whereas these for carebastine were 143 ± 68.4 ng/mL, 5.00 ± 2.00 h and 17.4 ± 4.97 h, respectively under fasting conditions; the corresponding values under fed conditions were 4.13 ± 2.53 ng/mL, 3.18 ± 1.09 h and 21.6 ± 7.77 h for ebastine and 176 ± 68.4 ng/mL, 6.14 ± 2.0 h and 20.0 ± 4.97 h for carebastine.

Dried Blood Spot Analysis for Therapeutic Drug Monitoring of Antipsychotics: Drawbacks of Its Clinical Application.

BACKGROUND: Dried blood spot (DBS) sampling offers a minimally invasive sampling method for therapeutic drug monitoring of antipsychotics. To facilitate implementation in clinical practice, the aim of this study was to perform a clinical validation study of a DBS method for quantification of risperidone, aripiprazole, pipamperone, and their major metabolites 9-OH risperidone and dehydro-aripiprazole in a real-life, clinical setting. METHODS: Paired DBS and venous plasma samples were analyzed (n = 35 for risperidone, n = 21 for aripiprazole, n = 21 for pipamperone). Estimated plasma concentrations were calculated from DBS concentrations based on hematocrit and/or Deming regression formulas. Deming regression and Bland-Altman analyses were used to determine the agreement between the calculated and measured plasma concentrations. For Bland-Altman analysis, the following acceptance limit was used: for a minimum of 67% of the samples, the difference of the 2 measurements should be within 20% of their mean. RESULTS: The median venous plasma levels were 0.9 mcg/L for risperidone, 14.8 mcg/L for 9-OH risperidone, 135.4 mcg/L for aripiprazole, 54.9 mcg/L for dehydro-aripiprazole, and 56.4 mcg/L for pipamperone. All antipsychotics required different correction formulas of DBS concentrations for best agreement. Subsequently, no constant or proportional bias was observed using Deming regression analysis. With Bland-Altman analyses, for risperidone, 45% of the samples were within the 20% limits; for 9-OH risperidone, 36%; for aripiprazole, 45%; for dehydro-aripiprazole, 35%; and for pipamperone, 43%. CONCLUSIONS: The DBS method to quantify risperidone, aripiprazole, pipamperone, and their major metabolites did not meet the acceptance criteria in the Bland-Altman analyses. Therefore, this DBS method was not clinically valid. This study shows the importance of a clinical validation study with use of Bland-Altman plots before clinical implementation.

Dried Blood Spots Combined With Ultra-High-Performance Liquid Chromatography-Mass Spectrometry for the Quantification of the Antipsychotics Risperidone, Aripiprazole, Pipamperone, and Their Major Metabolites.

BACKGROUND: Risperidone, aripiprazole, and pipamperone are antipsychotic drugs frequently prescribed for the treatment of comorbid behavioral problems in children with autism spectrum disorders. Therapeutic drug monitoring (TDM) could be useful to decrease side effects and to improve patient outcome. Dried blood spot (DBS) sample collection seems to be an attractive technique to develop TDM of these drugs in a pediatric population. The aim of this work was to develop and validate a DBS assay suitable for TDM and home sampling. METHODS: Risperidone, 9-OH risperidone, aripiprazole, dehydroaripiprazole, and pipamperone were extracted from DBS and analyzed by ultra-high-performance liquid chromatography-tandem mass spectrometry using a C18 reversed-phase column with a mobile phase consisting of ammonium acetate/formic acid in water or methanol. The suitability of DBS for TDM was assessed by studying the influence of specific parameters: extraction solution, EDTA carryover, hematocrit, punching location, spot volume, and hemolysis. The assay was validated with respect to conventional guidelines for bioanalytical methods. RESULTS: The method was linear, specific without any critical matrix effect, and with a mean recovery around 90%. Accuracy and imprecision were within the acceptance criteria in samples with hematocrit values from 30% to 45%. EDTA or hemolysis did not skew the results, and no punching carryover was observed. No significant influence of the spot volume or the punch location was observed. The antipsychotics were all stable in DBS stored 10 days at room temperature and 1 month at 4 or -80°C. The method was successfully applied to quantify the 3 antipsychotics and their metabolites in patient samples. CONCLUSIONS: A UHPLC-MS/MS method has been successfully validated for the simultaneous quantification of risperidone, 9-OH risperidone, aripiprazole, dehydroaripiprazole, and pipamperone in DBS. The assay provided good analytical performances for TDM and clinical research applications.

Identification and quantification of the antipsychotics risperidone, aripiprazole, pipamperone and their major metabolites in plasma using ultra-high performance liquid chromatography-mass spectrometry.

The antipsychotics risperidone, aripiprazole and pipamperone are frequently prescribed for the treatment in children with autism. The aim of this study was to validate an ultra-high performance liquid chromatography-mass spectrometry method for the quantification of these antipsychotics in plasma. An ultra-high performance liquid chromatography-mass spectrometry assay was developed for the determination of the drugs and metabolites. Gradient elution was performed on a reversed-phase column with a mobile phase consisting of ammonium acetate, formic acid in methanol or in Milli-Q ultrapure water at a flow rate of 0.5 mL/min. The method was validated according to the US Food and Drug Administration guidelines. The analytes were found to be stable enough after reconstitution and injection of only 5 µL improved the accuracy and precision in combination with the internal standard. Calibration curves of all five analytes were linear. All analytes were stable for at least 72 h in the autosampler and the high quality control of 9-OH-risperidone was stable for 48 h. The method allows quantification of all analytes. The advantage of this method is the combination of a minimal injection volume, a short run-time, an easy sample preparation method and the ability to quantify all analytes in one run. Copyright © 2015 John Wiley & Sons, Ltd.

Identification and quantification of 30 antipsychotics in blood using LC-MS/MS.

Over the last decade, the prescription rates of antipsychotic (AP) drugs have increased worldwide. Studies have shown that the risk of sudden cardiac death is threefold higher among patients treated with APs. To investigate the presence of APs in postmortem cases, a liquid chromatography (LC)-MS/MS method was developed using only 0.1 ml of blood sample with 10 microl of internal standard (IS) (haloperidol-d(4), 1 microg/ml). After the addition of 0.2 ml of Trizma buffer, the blood sample was extracted using liquid-liquid extraction (LLE) with 1 ml of 1-chlorobutane for 5 min on a shaker at 1500 rpm. After centrifugation at 12,000 rpm for 1 min, the separated solvent layer was transferred to an autosampler vial and evaporated to dryness under N(2). The residue was reconstituted in 0.05 ml acetonitrile containing 0.1% formic acid, vortexed for 30 s and an additional 0.45 ml of 50 mmol/l ammonium formate pH 3.5 was added and the sample vortexed; 0.1 ml of the final extract was injected into a Shimadzu Prominence HPLC system, with detection of drugs achieved using an Applied Biosystems 3200 Q-TRAP LC-MS/MS system equipped with a Turbo V ion source [electron spray ionization (ESI), multiple reaction monitoring (MRM) mode]. The method has been validated according to international guidelines and was found to be selective for all tested compounds. Calibration was satisfactory for all drugs, except olanzapine, from subtherapeutic to toxic concentrations. The lower limits of quantifications (LLOQs) corresponded to the lowest concentrations used for the calibration curves. With the exception of the lowest concentrations of bromperidol, buspirone and perphenazine, accuracy data were within the acceptance interval of +/- 15% (+/- 20% at LLOQ) of the nominal values for all drugs. The method has been proven to be useful for the routine analysis of APs in postmortem blood samples.

Application of a rapid and selective method for the simultaneous determination of carebastine and pseudoephedrine in human plasma by liquid chromatography-electrospray mass spectrometry for bioequivalence study in Korean subjects.

We describe a simple, rapid and sensitive high-performance liquid chromatography-electrospray ionization tandem mass spectrometric method that was developed for the simultaneous determination of carebastine and pseudoephedrine in human plasma using cisapride as an internal standard. Acquisition was performed in multiple-reaction monitoring mode by monitoring the transitions: m/z 500.43 > 167.09 for carebastine and m/z 166.04 > 147.88 for pseudoephedrine. The devised method involves a simple single-step liquid-liquid extraction with ethyl acetate. Chromatographic separation was performed on a C(18) reversed-phase chromatographic column at 0.2 mL/min by isocratic elution with 10 mM ammonium formate buffer-acetonitrile (30:70, v/v; adjusted to pH 3.3 with formic acid). The devised method was validated over 0.5-100 ng/mL of carebastine and 5-1000 ng/mL of pseudoephedrine with acceptable accuracy and precision, and was successfully applied to a bioequivalence study involving a single oral dose (10 mg of ebastine plus 120 mg of pseudoephedrine complex) to healthy Korean volunteers.

Automated on-line in-tube solid-phase microextraction coupled with HPLC/MS/MS for the determination of butyrophenone derivatives in human plasma.

This paper describes a fully automated on-line method combining in-tube solid-phase microextraction (SPME) in which sample clean-up and enrichment are conducted through an open tubular fused-silica capillary column and high-performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS) detection for the determination of six butyrophenone derivatives (moperone, floropipamide, haloperidol, spiroperidol, bromperidol, and pimozide) in human plasma samples. The six butyrophenones were extracted by repeatedly aspirating and dispensing plasma sample solutions on a DB-17 capillary column (60 cm x 0.32 mm i.d., film thickness 0.25 microm). The analytes retained on the inner surface of the capillary column were then eluted into an acetonitrile-rich mobile phase using a gradient separation technique. Extraction efficiencies ranged from 12.7% to 31.8% for moperone, spiroperidol, and pimozide, and from 1.08% to 4.86% for floropipamide, haloperidol, and bromperidol. The regression equations for all compounds showed excellent linearity, ranging from 0.05 to 50 ng/0.1 mL of plasma, except for moperone and spiroperidol (0.01 to 50 ng/0.1 mL). The limits of detection and quantification in plasma for each drug were 0.03-0.2 and 0.1-0.5 ng/mL, respectively. The intra- and inter-day coefficients of variation for all compounds in plasma were not greater than 13.7%.

Simultaneous determination of ebastine and its three metabolites in plasma using liquid chromatography-tandem mass spectrometry.

We developed a method for determining ebastine, a new generation of antihistamines, and its three metabolites (hydroxyebastine, carebastine and desalkylebastine) in plasma simultaneously using LC/MS/MS. Four compounds and terfenadine, an internal standard, were extracted from plasma using a mixture of diethylether and dichloromethane in the presence of 1 M HCl. After drying the organic layer, the residue was reconstituted in mobile phase (acetonitrile:5 mM ammonium acetate, 50:50, v/v) and injected onto a reversed-phase C(18) column. The isocratic mobile phase was eluted at 0.2 ml/min. The ion transitions monitored in multiple reaction-monitoring mode were m/z 470.7-->167.1, 486.7-->167.1, 500.6-->167.1, 268.4-->167.1 and 472.7-->436.0 for ebastine, hydroxyebastine, carebastine, desalkylebastine and terfenadine, respectively. The coefficient of variation of the assay precision was less than 12.5%, and the accuracy exceeded 88%. The limit of detection was 0.5 ng/ml for desalkylebastine; 0.2 ng/ml for ebastine, hydroxyebastine and carebastine, respectively. This method was used to measure the plasma concentration of ebastine and its three metabolites from healthy subjects after a single 20 mg oral dose of ebastine. This analytic method is a very simple, sensitive, and accurate to determine the pharmacokinetic profiles of ebastine including its metabolites.

A double-blind, placebo-controlled study of the efficacy and safety of ebastine 20 mg once daily given with and without food in the treatment of seasonal allergic rhinitis.

The efficacy and safety of ebastine 20 mg once daily given with and without food were compared in patients ages 12 to 70 years with seasonal allergic rhinitis (SAR) caused by mountain cedar allergen. This double-blind, placebo-controlled study was conducted at six centers in Texas. Efficacy and safety analyses were performed on the intent-to-treat population, which comprised 652 patients; 540 patients completed the study. Following 2 weeks' treatment, no significant differences (p > or = 0.91) were found between the ebastine with and without food groups in the percentage change from baseline of daily "reflective" total rhinitis symptom scores (i.e., patients' assessment of severity over the previous 12 h), but both ebastine groups exhibited significantly greater reductions versus patients receiving placebo (p < 0.0001). There were also no significant differences in the percentages of patients experiencing adverse events between the ebastine with and without food groups. Mean steady-state plasma concentrations of ebastine and its active metabolite carebastine were, respectively, 5.5% (ns) and 15.1% (p < 0.05) higher when ebastine was given with food versus its administration without food. Overall, these results indicate that in clinical practice, ebastine does not need to be administered with reference to food.

Differential cognitive effects of ebastine and (+)-chlorpheniramine in healthy subjects: correlation between cognitive impairment and plasma drug concentration.

AIMS: It has been widely recognized that classical antihistamines induce sedation as an adverse effect, while second-generation antihistamines have few if any sedative effects. In order to evaluate the sedative properties of ebastine, a second-generation antihistamine, its effect on cognitive performance in healthy subjects was compared with placebo and (+)-chlorpheniramine. METHODS: Twelve healthy male subjects were instructed to perform six types of attention-demanding cognitive tasks, and objective measurements of reaction times and accuracy was made before and after drug administration. Their sleepiness levels were also monitored. Test drugs were ebastine 10 mg, placebo and two doses of (+)-chlorpheniramine 2 mg and 6 mg, as positive controls. Plasma drug concentrations at the end of the study were analysed. RESULTS: After treatments with (+)-chlorpheniramine, the reaction times of the tasks were significantly prolonged (e.g. ratios of after/before dosing: placebo (0.998 +/- 0.113) vs (+)-chlorpheniramine 2 mg (1.103 +/- 0.083; P<0.05) or (+)-chlorpheniramine 6 mg (1.170 +/- 0.139; P<0.001) in a 7 ms visual discrimination time task) and the accuracy was significantly decreased (e.g. ratios: placebo (1.038 +/- 0.158) vs (+)-chlorpheniramine 2 mg (0.792 +/- 0.202; P<0.01) or (+)-chlorpheniramine 6 mg (0.837 +/- 0.222; P<0.05) in a 7 ms task). On the other hand, performance was not affected by ebastine or placebo treatment (e.g. ebastine 10 mg (reaction time ratio; 1.014 +/- 0.067 and accuracy ratio; 0.990 +/- 0.146) in a 7 ms task). Subjective sleepiness was also not affected by ebastine but (+)-chlorpheniramine significantly increased sedation. With respect to the relationship between plasma drug concentrations and task performance, the latter deteriorated with an increase in plasma (+)-chlorpheniramine concentration (e.g. r=0.439 (P=0.007) in a 5 ms and r = 0.352 (P=0.039) in a 7 ms task), but it did not correlate with the plasma concentration of carebastine, an active metabolite of ebastine. CONCLUSIONS: Ebastine 10 mg did not cause any cognitive impairment or subjective sleepiness. On the other hand, (+)-chlorpheniramine impaired cognitive function and induced sleepiness even at 2 mg, the recommended dose in over-the-counter medication. In addition, impaired CNS performance was significantly correlated with plasma (+)-chlorpheniramine concentration.

Simultaneous determination of the histamine H1-receptor antagonist ebastine and its two metabolites, carebastine and hydroxyebastine, in human plasma using high-performance liquid chromatography.

Ebastine (CAS 90729-43-4) is an antiallergic agent which selectively and potently blocks histamine H1-receptors in vivo. A simple and sensitive high-performance liquid chromatography (HPLC) method is described for the simultaneous determination of ebastine and its two oxidized metabolites, carebastine (CAS 90729-42-3) and hydroxyebastine (M-OH), in human plasma. After a pretreatment of plasma sample by solid-phase extraction, ebastine and its metabolites were analyzed on an HPLC system with ultraviolet detection at 254 nm. Chromatography was performed on a cyano column (250x4.0 mm I.D.) at 40 degrees C with the mobile phase of acetonitrile-methanol-0.012 M ammonium acetate buffer (20:30:48, v/v/v) at a flow rate of 1.2 ml/min. Accurate determinations were possible over the concentration range of 3-1000 ng/ml for the three compounds using 1 ml plasma samples. The intra- and inter-day assay accuracy of this method were within 100+/-15% of nominal values and the precision did not exceed 12.4% of relative standard deviation. The lower limits of quantitation were 3 ng/ml for ebastine and its metabolites in human plasma. This method was satisfactorily applied to the determination of ebastine and its two oxidized metabolites in human plasma after oral administration of ebastine.

Analyses of butyrophenones and their analogues in whole blood by high-performance liquid chromatography-electrospray tandem mass spectrometry.

Five butyrophenones and two analogues contained in human whole blood have been analyzed by high-performance liquid chromatography (HPLC)-electrospray (ES)-tandem mass spectrometry (MS). All compounds gave the base peaks due to [M+1]+ by HPLC-ES-single MS. The product ions formed from each quasi-molecular ion by HPLC-ES-tandem MS showed the base peaks at m/z 165 for four compounds. The mass chromatography of HPLC-ES-tandem MS showed much higher sensitivity than that of HPLC-ES-single MS for all drugs spiked to whole blood. Therefore, regression equations, detection limits, recovery rates and precision were studied for haloperidol, bromperidol and fluoropipamide spiked to human whole blood by means of mass chromatography of HPLC-ES-tandem MS. The three compounds showed good linearity in the range of 0.2-0.8 ng/ml with a detection limit of about 0.1 ng/ml. Recoveries of the three compounds spiked to whole blood (0.2 and 0.8 ng added to 1 ml whole blood) were 23.6-81.2%; the coefficients of intra- and inter-day variations were 8.4-10.4 and 14.5-17.5%, respectively. The three compounds in whole blood could be actually determined 3 and 6 h after oral administration of 1 mg each of haloperidol and bromperidol, and 10 mg of floropipamide in a volunteer.

Pharmacokinetic-pharmacodynamic analysis of the arrhythmogenic potency of a novel antiallergic agent, ebastine, in rats.

Ebastine (EBS), a novel nonsedative antiallergic agent, is similar to terfenadine in its chemical structure. However, clinical arrhythmogenicity of EBS remains controversial. In this study, we evaluated the possible arrhythmogenic potency of EBS as assessed by QT prolongation from a pharmacokinetic-pharmacodynamic viewpoint in comparison with that of terfenadine. EBS was intravenously infused into anesthetized rats at a rate of 3.0 or 10 mg/kg/h for 60 min, and electrocardiographic effects were continuously monitored from lead II. The plasma concentrations of EBS and its major metabolite, carebastine, were also measured under the same conditions. When intravenously administered, EBS exhibited QT prolongation in an infusion rate-dependent manner, with a lag time. Pharmacokinetic-pharmacodynamic analysis of EBS based on the effect-compartment model revealed values of EC50, Emax and EC(10 ms), (where 10 ms of QT prolongation was evoked) of 0.73 microg/mL, 12.5 ms and 2.90 microg/mL, respectively. The EC(10 ms) value of EBS was five times higher than that of terfenadine reported previously (Ohtani et al., J. Pharm. Pharmacol., 49, 458-462 (1997)). In conclusion, EBS was suggested to be less arrhythmogenic than terfenadine.

Comparative study of different weighting methods in non-linear regression analysis: implications in the parametrization of carebastine after intravenous administration in healthy volunteers.

The influence of different weighting methods in non-linear regression analysis was evaluated in the pharmacokinetics of carebastine after a single intravenous dose of 10 mg in 8 healthy volunteers. Plasma concentrations were measured by HPLC using an on-line solid-phase extraction method and automated injection. The analytical method was fully validated and the function of the analytical error subsequently determined. The parametric approach was performed using different weighting methods, including the homoscedastic method (W = 1) and heteroscedastic methods using weights of 1/C, 1/C2, and the inverse of the concentration variance calculated through the analytical error function (1/V), and the results were statistically evaluated according to the normal distribution. Statistically significant differences were observed in the representative parameters of the disposition kinetics of carebastine. The use of a multiple comparison test for statistical analysis of all differences among group means indicated that differences were generated between the homoscedastic method (W = 1) and the heteroscedastic methods (1/C, 1/C2, and 1/V). The results obtained in the present study confirmed the utility of the analytical error function as a weighting method in non-linear regression analysis and reinforced the importance of the correct choice of weights to avoid the estimation of imprecise or erroneous pharmacokinetic parameters.

Plasma concentrations of antipsychotic drugs in psychiatric inpatients.

In current psychiatric therapy, two or more kinds of antipsychotic drugs are usually prescribed in Japan. However, there are few data on the therapeutic plasma concentrations of antipsychotic drugs or on the correlation between the daily dose and the plasma concentration, in cases where several antipsychotic drugs had been prescribed for each patient. We measured the therapeutic plasma concentrations of 9 antipsychotic drugs in 24 psychiatric inpatients during a 6-month period. They were treated with fixed dosages of antipsychotic drugs. Plasma samples were collected early in the morning once a month, and the concentrations of antipsychotic drugs were determined by gas chromatography with nitrogen phosphorus detection, high-performance liquid chromatography (HPLC) with fluorescence detection and HPLC with UV detection. The plasma levels of chlorpromazine, levomepromazine, thioridazine, haloperidol, bromperidol, zotepine, oxypertine, sulpiride and sultopride were 21.8-92.4, 31.7-156, 101-203, 16.4-56.2, 2.72-11.7, 13.6-84.0, 29.9-80.4, 70.1-1,120 and 35.7-2,990 ng/ml, respectively. A linear correlation between the daily dose and the plasma concentration was noted for sultopride, levomepromazine, sulpiride, haloperidol, chlorpromazine and zotepine.

Liquid chromatographic-thermospray tandem mass spectrometric quantitative analysis of some drugs with hypnotic, sedative and tranquillising properties in whole blood.

Results are presented of a liquid chromatographic-thermospray tandem mass spectrometric method of analysing different drugs in whole blood. Substances with hypnotic, sedative and tranquillising properties from the benzodiazepine, the thioxanthene, the butyrophenone, the methadone and the diphenylbutylpiperidine groups were investigated. It appears that ten to hundred times lower detection limits for the substances in whole blood can be reached with this method compared with methods more commonly used. Detection limits in the range 10-100 pg per injection (equivalent to 0.05-0.5 ng/ml whole blood) were reached for the majority of the compounds.

Determination of timiperone in rat plasma by high-performance liquid chromatography with electrochemical detection.

We report a sensitive new method for the determination of timiperone in rat plasma by using high-performance liquid chromatography with electrochemical detection. The method involves extraction of plasma samples with heptane-isoamyl alcohol at pH > 8, followed by back-extraction into dilute acetic acid. Separation was accomplished by reversed-phase high-performance liquid chromatography on an ODS column with the mobile phase consisting of 0.1 M phosphate buffer (pH 3.5)-acetonitrile-methanol (65:20:15, v/v). Recovery was greater than 80%. Calibration curve was linear over the concentration range 0.5-50.0 ng/ml. The limit of quantitation of timiperone was 0.5 ng/ml plasma.

Gas chromatographic determination of diisopyramide in the presence of some butyrophenones in human plasma.

A gas chromatographic procedure with flame ionization detection for the simultaneous determination of diisopyramide and butyrophenones in plasma was developed and evaluated. The quantitative analysis of diisopyramide and butyrophenones (BTPs) was performed in gas chromatograph equipped with packed column (glass column packed with 3% of phenylmethyl silicone-20% ph.), with previous Solid Phase Extraction (SPE) of drugs in C18 minicolumns. For all the drugs considered the accuracy of the proposed method has been evaluated through the recovery test which fell in the range 93-99%, once the absence of matrix interferences has been verified. The precision, expressed as coefficient of variation (CV%), has been of the order of 4%. A 15 m x 0.32 mm i.d. crosslinked, 5% phenylmethyl silicone-coated fused-silica column was also quantitatively utilized and samples were injected using the on-column mode.