1,720,974 research outputs found
Separation and HPLC analysis of 15 benzodiazepines in human plasma
No full textBenzodiazepines (BZDs) are often prescribed to schizophrenic or depressed patients, as a part of polypharmacy regimens. An HPLC method has been developed for the simultaneous determination of 15 BZDs in human plasma. Separation was obtained by using a C8 RP column and a mobile phase composed of 65% aqueous phosphate buffer at pH 3.0 and 35% ACN. The UV detector was set at 220 nm and clomipramine was used as the internal standard. A careful pretreatment procedure of plasma samples was developed, using SPE with C1 cartridges, which gives high extraction yields (> 97%). The LOQs were always lower than 7.6 ng/mL and the LODs always lower than 2.6 ng/mL for all analytes. The method was successfully applied to plasma samples from depressed and schizophrenic patients undergoing polypharmacy with one or more BZDs. Precision data, as well as accuracy results, were satisfactory and no interference from other drugs was found. Hence, the method seems to be suitable for the therapeutic drug monitoring (TDM) of patients undergoing therapy with one or more BZD
HPLC analysis of the novel antidepressant duloxetine in human plasma after an original solid-phase extraction procedure
No full textHPLC analysis of the antidepressant trazodone and its main metabolite m-CPP in human plasma
No full textThe present paper deals with the development of a rapid and feasible high-performance liquid chromatographic method for the determination of trazodone and its main active metabolite 3-(1-clorophenyl)piperazine (m-CPP) in human plasma. Trazodone is a second-generation antidepressant with serotonin antagonist activity. The metabolite seems to be involved in the onset of some side effects of trazodone therapy, thus its determination is very important during therapeutic drug monitoring. Separation was achieved using a C8 reversed-phase column and a mobile phase composed of aqueous phosphate buffer (70%), containing triethylamine, at pH 3.5 and acetonitrile (30%). The UV detector was set at 255 nm and loxapine was used as the internal standard. An original pre-treatment procedure of plasma samples was developed, based on solid-phase extraction with C8 reversed phase cartridges (50mg, 1 mL). The obtained extraction yields values were higher than 90% and precision, expressed as R.S.D., was lower than 5.6%. The method was successfully applied to plasma samples from depressed patients undergoing therapy with trazodone; accuracy results were satisfactory (recovery >91%). Thus, the method seems to be suitable for the therapeutic drug monitoring of trazodone and its main active metabolite in depressed patients' plasma
Simultaneous high-performance liquid chromatographic determination of olanzapine and lamotrigine in plasma of bipolar patients
No full textAn original method based on the use of high-performance liquid chromatography with both coulometric and diode array detection has been developed for the therapeutic drug monitoring of patients with bipolar disorders being treated with olanzapine and lamotrigine. Chromatographic separation was achieved on a reversed-phase C8 column (150 x 4.6 mm internal diameter, 5 microm) using a mobile phase composed of methanol (27%) and a 50.0 mmol/L, pH 3.5 phosphate buffer (73%). For the analysis of olanzapine and its main metabolite, N-desmethylolanzapine, a coulometric detector was used, with electrode 1 set at -200 mV and electrode 2 at +500 mV. Lamotrigine was determined using a diode array detection at 220 nm. The two detectors were connected in series. For the analysis of biological samples, a clean-up procedure was implemented by means of solid-phase extraction using phenyl cartridges and eluting the analytes with methanol; only a small volume of plasma (150 microL) was needed to analyze both olanzapine and lamotrigine. Linear responses were obtained between 0.1 and 50.0 ng mL(-1) for olanzapine, 0.1 and 25.0 ng mL(-1) for N-desmethylolanzapine, and between 0.25 and 10.0 microg mL(-1) for lamotrigine. The extraction yield values were always higher than 90% for all the analytes, with precision (expressed as relative standard deviation values) lower than 3.4%. The method was applied successfully to some human plasma samples drawn from bipolar patients undergoing combined therapy with the two drugs. Satisfactory values for accuracy were obtained, with mean recovery higher than 91%. Thus, the method appears suitable for the investigation of the chemical-clinical correlations in patients receiving therapy with olanzapine and lamotrigine
Rapid HPLC analysis of the antiepileptic lamotrigine and its metabolites in human plasma
No full textA liquid chromatographic method with diode array detection (DAD) has been developed for the analysis of the antiepileptic agent lamotrigine (LTG) and its metabolites, lamotrigine 2-N-glucuronide and 2-N-methylated in plasma samples. The analytes were separated on a C8 RP column, using a mobile phase composed of methanol and a 0.45 mM, pH 3.5 phosphate buffer containing 0.17% triethylamine (24:76 v/v). Melatonin was used as the internal standard (IS). The DAD detector was set at 220 nm for the detection of all the analytes. A simple protein precipitation with methanol guaranteed high extraction yield values (>90%) and good purification from matrix interference. Good linearity was obtained in the 0.1-15.0 microg/mL range for LTG and lamotrigine 2-N-glucuronide and in the 0.1-2.0 microg/mL range for lamotrigine 2-N-methylated. The analytical method was validated in terms of precision, extraction yield, and accuracy. These assays gave RSD% values for precision always lower than 4.3% and mean accuracy higher than 80%. The method seems to be suitable for the analysis of plasma samples from patients treated with Lamicta
HPLC analysis of the novel antidepressant duloxetine in human plasma after an original solid-phase extraction procedure
No full textDuloxetine is the most recent serotonin and norepinephrine reuptake inhibitor (SNRI) drug introduced for the therapy of depression. Thus, it is evident that there is a need for having on hand new reliable analytical methods for the determination of duloxetine plasma levels in depressed patients. The present paper deals with the development of a rapid and sensitive high-performance liquid chromatographic method for duloxetine analysis in human plasma. The assays were carried out using a C8 reversed-phase column and a mobile phase composed of 60% aqueous phosphate buffer containing triethylamine at pH 3.0 and 40% acetonitrile. The UV detector was set at 230 nm and loxapine was used as the internal standard. An original pre-treatment of plasma samples was developed, based on solid-phase extraction (SPE) with mixed-mode reversed phase-strong cation exchange cartridges (30 mg, 1 mL). The extraction yields values were higher than 90%. Linearity was found in the 2-200 ng mL(-1) duloxetine concentration range; the limit of quantitation was 2.0 ng mL(-1) and the limit of detection was 0.7 ng mL(-1). The method was applied to plasma samples from depressed patients undergoing therapy with duloxetine. Precision data and accuracy results were satisfactory and no interference from other drugs was found. Thus, the method seems to be suitable for the therapeutic drug monitoring of duloxetine in depressed patients' plasm
Simultaneous high-performance liquid chromatographic determination of olanzapine and lamotrigine in plasma of bipolar patients
No full textRapid HPLC analysis of the antiepileptic lamotrigine and its metabolites in human plasma
No full textDetermination of selected phenothiazines in human plasma by solid-phase extraction and liquid chromatography with coulometric detection.
No full textA new analytical method, based on liquid chromatography with coulometric detection, has been developed and applied to the determination of selected phenothiazines (chlorpromazine, promazine, fluphenazine and levomepromazine) in human plasma. The drugs were separated on a Discovery pentafluorophenylpropyl column, using a mobile phase composed of acetonitrile (32%) and a pH 1.9 phosphate buffer (68%). Promethazine was used as the internal standard. Detection was carried out at an oxidation potential of +0.500 V. A novel clean-up procedure was developed by means of solid-phase extraction, using cyanopropyl cartridges, which gave good extraction yield for all the analytes, with absolute recovery values higher than 91.0%. The detector response was linear over a plasma concentration range of 0.5-250.0 ng mL(-1) for chlorpromazine, promazine and levomepromazine and of 0.2-4.0 ng mL(-1) for fluphenazine. Precision results, expressed by the intra-day and the inter-day relative standard deviation values, were good, being lower than 3.9%. Accuracy data were satisfactory as well. The method has been successfully applied to the analysis of drug plasma levels of psychiatric patients undergoing therapy with selected phenothiazine
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