Selective electrochemical detection of antidepressant drug imipramine in blood serum and urine samples using an antimony telluride-graphite nanofiber electrode.

A high-performance imipramine (IMPR) sensor has been developed  based on metal chalcogenide-carbon composite materials. The antimony telluride-graphite nanofiber (Sb2Te3-GNF, hereafter SBT-GNF) composite was synthesized by the hydrothermal method and confirmed by X-ray powder diffraction (XRD) pattern. The morphology, crystalline lattice, and chemical states were characterized by HRTEM, SAED, and XPS analysis. The characterizations confirmed the formation of an effective composite, SBT-GNF. The SBT-GNF was fabricated as a disposable sensor electrode with a screen-printed carbon electrode (SPCE) and examined for the detection of IMPR by differential pulse voltammetry (DPV). The electroanalytical results of SBT-GNF are compared with the SBT and GNF, and the rational design of effective composite is discussed. SBT-GNF/SPCE showed a good linear range (0.01­51.8 µM), sensitivity (1.35 ± 0.1 µA µM-1 cm-2), and low LOD (4 ± 2 nM). Moreover, the SBT-GNF/SPCE revealed high selectivity and high tolerance limit against potential interfering compounds in blood serum and urine samples. Therefore, this electrochemical sensor can be applicable for the detection of tricyclic antidepressant drug IMPR in clinical and pharmaceutical analysis.

A green and low-cost method employing switchable hydrophilicity solvent for the simultaneous determination of antidepressants in human urine by gas chromatography - mass spectrometry detection.

In this study, the use of switchable hydrophilicity solvent with a simple and low-cost lab-made device for the extraction procedure in homogeneous liquid-liquid microextraction is proposed for the first time in the determination of antidepressants in human urine. The antidepressants studied consisted of fluoxetine, amitriptyline, nortriptyline, imipramine, desipramine and sertraline. The optimization of the main parameters that can influence on the extraction efficiency was performed through multivariate approaches. The analytes were separated and identified by gas chromatography coupled to mass spectrometry (GC-MS). The optimal extraction conditions consisted of using N,N-dimethylcyclohexylamine (DMCHA) as the switchable hydrophilicity solvent (SHS), 500 µL of urine sample previously diluted with ultrapure water at 1:1 ratio (v/v), 200 µL of a mixture of SHS:HCl 6 mol L-1 (1:1 v/v), 600 µL of NaOH 10 mol L-1 and 3 min of extraction time. A volume of 40 µL of diphenylamine at concentration of 500 µg L-1 (20 ng) was used as internal standard. The method developed was in-house validated, providing coefficients of determination higher than 0.995 for all analytes, limits of detection (LOD) from 0.02 to 0.88 µg L-1, limits of quantification (LOQ) from 0.05 to 2.92 µg L-1, relative recoveries of 68 to 102%, intra-day precision from 0.5 to 15.9%, inter-day precision from 4.2 to 19.3%, selectivity and robustness. The method proposed was successfully applied in five human urine samples from a Toxicological Information Center located in Porto Alegre (Brazil). The results demonstrated that the µP-SHS-HLLME approach is highly cost-effective, rapid, simple and environmentally-friendly with satisfactory analytical performance.

Supramolecular microextraction combined with paper spray ionization mass spectrometry for sensitive determination of tricyclic antidepressants in urine.

This work describes a novel methodology to analyze four tricyclic antidepressants (amitriptyline, doxepin, imipramine and, nortriptyline) in urine samples by combining supramolecular microextraction and paper spray ionization mass spectrometry (PS-MS). The proposed method uses a supramolecular solvent in which reverse micelles of 1-decanol are dispersed in tetrahydrofuran (THF)/water. The extraction of the tricyclic antidepressants at pH 9.0 requires a sample volume of 10.0 mL, short extraction time (1.0 min of extraction and 5 min of centrifugation), low amounts of organic solvent (50 µL of 1-decanol and 200 µL of THF), and provides high preconcentration factors: 96.9 to amitriptyline, 93.6 to doxepin, 71.3 to imipramine, and 146.9 to nortriptyline. The quantification by PS-MS is fast and straightforward because chromatographic separation is not required and all analytes were determined simultaneously. The limits of detection (LOD), quantification (LOQ), and the precision (RSD, %) of the developed method ranged between 5.2 and 8.6 µg L-1, 17.4-28.7 µg L-1 and 1.3-12.9%, respectively. Urine samples of five individuals (three males and two females) were used for accuracy evaluation. The accuracy obtained in these spiked urine samples at µg L-1 levels varied from 95.3 to 112.0%. The method also provided clean mass spectra with a high signal-to-noise ratio, which demonstrates the analytical appeal combination of supramolecular microextraction with determination by paper spray mass spectrometry.

Combination of electromembrane extraction and electro-assisted liquid-liquid microextraction: A tandem sample preparation method.

As a well-known extraction procedure, electromembrane extraction (EME) was combined with electro-assisted liquid-liquid microextraction (EA-LLME) in the present work, which resulted in a promising method. This hyphenated sample preparation method, named EME-EA-LLME, was followed by GC for the determination of two model analytes (clomipramine and imipramine). The effective parameters of both EME and EA-LLME (such as organic solvent, pH of acceptor and sample solutions, voltage and extraction time) were optimized. The proposed EME-EA-LLME procedure demonstrated good linearity with coefficients of determination, R2 ≥ 0.998 over the concentration range of 0.5-750 ng/mL. Limit of detection for both analytes was 0.15 ng/mL. The corresponding repeatability ranged from 6.9 to 12.2% (n = 3). The high enrichment factors were obtained as 770.3 and 561.4 for imipramine and clomipramine, respectively. The advantages of this tandem sample preparation method were low detection limits, simplicity, low cost, and short analysis time (<10 min). Finally, the optimized method was used to extract and determine the analytes in urine and wastewater samples. Overall, the results revealed that the developed EME-EA-LLME procedure had better extraction efficiency in comparison with EME and EA-LLME alone.

High performance liquid chromatographic determination of ultra traces of two tricyclic antidepressant drugs imipramine and trimipramine in urine samples after their dispersive liquid-liquid microextraction coupled with response surface optimization.

Dispersive liquid-liquid microextraction (DLLME) coupled with high performance liquid chromatography by ultraviolet detection (HPLC-UV) as a fast and inexpensive technique was applied to the determination of imipramine and trimipramine in urine samples. Response surface methodology (RSM) was used for multivariate optimization of the effects of seven different parameters influencing the extraction efficiency of the proposed method. Under optimized experimental conditions, the enrichment factors and extraction recoveries were between 161.7-186.7 and 97-112%, respectively. The linear range and limit of detection for both analytes found to be 5-100ng mL(-1) and 0.6ng mL(-1), respectively. The relative standard deviations for 5ng mL(-1) of the drugs in urine samples were in the range of 5.1-6.1 (n=5). The developed method was successfully applied to real urine sample analyses.

Variability in metabolism of imipramine and desipramine using urinary excretion data.

Variability in imipramine and desipramine metabolism was evaluated using urinary excretion data from patients with pain. Liquid chromatography-tandem mass spectrometry was used to quantitate concentrations in urine specimens. Interpatient population contained 600 unique imipramine specimens, whereas intrapatient population had 137 patients with two or more specimens. Normal concentration ranges of imipramine, desipramine and the desipramine/imipramine metabolic ratio (MR) were established, and various factors were tested for MR impact. Geometric mean of imipramine urine concentration was 0.46 mg/g of creatinine, and desipramine was 0.67 mg/g of creatinine. Gender, concomitant known CYP2C19 inhibitor use and urine pH did not affect MR. However, proton-pump inhibitor (PPI) users had a significantly lower mean MR than those without a listed PPI. Early age group (18-36 years) had a significantly higher mean MR than middle (37-66 years) and late (67-90 years) age groups. Approximately one-third were positive for one or more of hydrocodone, oxycodone, hydromorphone or oxymorphone. Patients with no opioids reported in the medication list had a significantly lower geometric mean MR than those with prescribed opioids (1.03 vs. 1.54, P = 0.004). Patients with only one prescribed opioid had a lower MR than those with two or more prescribed opioids. Patients with younger age, prescribed opioids and no listed PPI were more likely to have a higher geometric mean urinary desipramine/imipramine MR.

Tricyclic antidepressants: is your patient taking them? Observations on adherence and unreported use using prescriber-reported medication lists and urine drug testing.

OBJECTIVE: Tricyclic antidepressants (TCAs) are first-line treatment for neuropathic pain. Despite widespread use, many health care providers do not know which patients are currently taking TCAs. The objective of this retrospective data analysis was to determine adherence rates to amitriptyline, nortriptyline, or imipramine. The rate at which patients used TCAs (confirmed by presence of TCA in the urine) but did not inform their health care provider is also reported (non-informed prescriber rate). Finally, the effects of age, sex, and number of prescriptions on adherence and non-informed prescriber rates were assessed. METHODS: Urinary excretion data were obtained from 55,296 patients with pain and were analyzed using liquid chromatography tandem mass spectrometry in a multiplex assay which included amitriptyline, nortriptyline, and imipramine. RESULTS: The adherence rate was 66% (1,407/2,137); the rate of non-informed prescribers was 3% (1,547/55,296) among the general population, and 52% (1,547/2,954) when only TCA users were considered. While adherence was higher among older and female subjects, the number of other medications did not affect adherence rate. CONCLUSIONS: This analysis reveals that many prescribers are not informed when patients start and stop using TCAs.

Synthesis of palladium nanoparticles on organically modified silica: application to design of a solid-state electrochemiluminescence sensor for highly sensitive determination of imipramine.

Organically modified silica substrate containing amine and vinyl functional groups were used for reduction and stabilization of palladium nanoparticles. Uniform spherical nanoparticles of palladium with average diameter of 10 nm were formed on silica substrate by direct contact of the substrate with an aqueous solution of palladium precursor, without the addition of any chemical reducer. Moreover, a sensitive and selective solid state electrochemiluminescence sensor was fabricated for the determination of imipramine, based on Ru(bpy)3(2+)-palladium nanoparticles doped carbon ionic liquid electrode. In this process, imipramine acts as a co-reactant for Ru(bpy)3(2+). It is believed that the enhancement of the electrochemiluminescence signal in the presence of palladium nanoparticles in the composite is due to palladium catalytic effect on electrochemical and also chemical process involved in formation of Ru(byp)3(2+)*. In addition, the results confirmed that, the rigid composite electrode shows the characteristic of microelectrode arrays. The proposed method was applied to the determination of imipramine in tablets and urine samples. The electrochemiluminescence intensity showed good linearity with the imipramine concentration from 1-100 pM, with a detection limit of 0.1 pM.

Adsorptive stripping voltammetric determination of imipramine, trimipramine and desipramine employing titanium dioxide nanoparticles and an Amberlite XAD-2 modified glassy carbon paste electrode.

An Amberlite XAD-2 (XAD2) and titanium dioxide nanoparticles (TNPs) modified glassy carbon paste electrode (XAD2-TNP-GCPE) was developed for the determination of imipramine (IMI), trimipramine (TRI) and desipramine (DES). The electrochemical behavior of these molecules was investigated employing cyclic voltammetry (CV), chronocoulometry (CC), electrochemical impedance spectroscopy (EIS) and adsorptive stripping differential pulse voltammetry (AdSDPV). After optimization of analytical conditions using a XAD2-TNP-GCPE electrode at pH 6.0 phosphate buffer (0.1 M), the peak currents were found to vary linearly with its concentration in the range of 1.30 × 10(-9) to 6.23 × 10(-6) M for IMI, 1.16 × 10(-9) to 6.87 × 10(-6) M for TRI and 1.43 × 10(-9) to 5.68 × 10(-6) M for DES. The detection limits (S/N = 3) of 3.93 × 10(-10), 3.51 × 10(-10) and 4.35 × 10(-10) M were obtained for IMI, TRI and DES respectively using AdSDPV. The prepared modified electrode showed several advantages such as a simple preparation method, high sensitivity, very low detection limits and excellent reproducibility. The proposed method was employed for the determination of IMI, TRI and DES in pharmaceutical formulations, blood serum and urine samples.

Electromembrane extraction combined with gas chromatography for quantification of tricyclic antidepressants in human body fluids.

Recent advances in electromembrane extraction (EME) methodology calls for effective and accessible detection methods. Using imipramine and clomipramine as model therapeutics, this proof-of-principle work combines EME with gas chromatography analysis employing a flame ionization detector (FID). The drugs were extracted from acidic aqueous sample solutions, through a supported liquid membrane (SLM) consisting of 2-nitrophenyl octyl ether (NPOE) impregnated on the walls of the hollow fiber. EME parameters, such as SLM composition, type of ion carrier, pH and the composition of donor and acceptor solutions, agitation speed, extraction voltage, and extraction time were studied in detail. Under optimized conditions, the therapeutics were effectively extracted from different matrices with recoveries ranging from 90 to 95%. The samples were preconcentrated 270-280 times prior to GC analysis. Reliable linearity was also achieved for calibration curves with a regression coefficient of at least 0.995. Detection limits and intra-day precision (n=3) were less than 0.7 ng mL(-1) and 8.5%, respectively. Finally, method was applied to determination and quantification of drugs in human plasma and urine samples and satisfactory results were achieved.

Fast urinary screening for imipramine and desipramine using on-line solid-phase extraction and selective derivatization.

A continuous-flow configuration based on sequential solid-phase extraction and derivatization is proposed for the screening of urine samples for imipramine and related metabolites. For the first time, a 50/50 (v/v) methanol/nitric acid mixture is used as both eluent and derivatizing reagent. Sample aliquots are injected into the flow manifold and driven by a water stream to an RP-C(18) column where the drugs are quantitatively retained. Following clean-up step with 40/60 (v/v) methanol/water, the eluent/derivatizing reagent is injected and passed through the sorbent column, eluted drugs reacting with nitric acid to form a blue dye that is monitored at 600 nm. The global signal thus obtained for the antidepressants can be used to estimate their total concentration in the samples without the need to individually quantify the analytes. This total index can be used for timely decision-making in case of overdosage. The proposed method is sensitive and selective; thus, typical interferents such as endogenous and diet compounds have no substantial effect on the analytical signal. This allows imipramine and its metabolites to be determined at therapeutic levels in urine samples.

Flow injection chemiluminescence determination of imipramine in tablets, human plasma and urine samples based upon oxidation with singlet oxygen generated in N-bromosuccinimide-hydrogen peroxide reaction.

Singlet oxygen generated in a reaction between N-bromosuccinimide and hydrogen peroxide was used for the chemiluminescence oxidation of imipramine. A strong chemiluminescence signal was observed when imipramine was mixed with N-bromosuccinimide and hydrogen peroxide under an alkaline condition. The chemiluminescence signal was linearly dependent on the concentration of imipramine in the range of 0.01 - 1.0 mg/L. The detection limit was 0.005 mg/L imipramine and the relative standard deviation was 1.5% for a 0.4 mg/L imipramine solution in 11 repeated measurements. The proposed method was successfully applied to the determination of imipramine in tablets, human plasma and urine samples.

Sample preparation with fiber-in-tube solid-phase microextraction for capillary electrophoretic separation of tricyclic antidepressant drugs in human urine.

Solid-phase microextraction (SPME) is a solvent-free sample preparation technique using a thin coating attached to the surface of a fused silica-fiber as the extraction medium, which has been successfully applied to the analysis of a wide variety of compounds by coupling to gas chromatography (GC). In recent years, in-tube SPME using GC capillary column as the extraction medium has also been developed and coupled with liquid chromatography (LC) for the preconcentration of nonvolatile compounds. In this study, an on-line interface between the fiber-in-tube SPME and capillary electrophoresis (CE) has been developed, and the preconcentration and separation of four tricyclic antidepressant (TCA) drugs, amitriptyline, imipramine, nortriptyline, and desipramine, were performed with the hyphenated system. Under the optimized condition, a better extraction performance than conventional in-tube SPME was obtained, even the length of the extraction medium was much shorter. The results clearly indicated that the fiber was working effectively as an extraction medium. For the separation of these four TCAs, capillary electrophoretic separation with beta-cyclodextrin as the buffer additive has been employed and the application of the developed system to the analysis of complex sample mixtures in a biological matrix is also demonstrated.

Simultaneous determination of imipramine, desipramine and their 2- and 10-hydroxylated metabolites in human plasma and urine by high-performance liquid chromatography.

A simultaneous assay for imipramine, desipramine and their 2- and 10-hydroxy-metabolites using high-performance liquid chromatography (HPLC) is described. The drugs and internal standard, pericyazine, were extracted from plasma or urine at pH 9.6 with diethyl ether and back-extracted into 0.1 M orthophosphoric acid. The recovery of the compounds ranged from 78.6% for imipramine to 94.3% for 2-hydroxydesipramine. The extracts were analysed by reversed-phase HPLC with electrochemical detection using a mobile phase of 30% acetonitrile in 0.1 M K2HPO4 at pH 6.0 delivered at 2 ml/min. All compounds were resolved in a run time of 15 min with lower limits of quantification of 1.5 ng/ml for hydroxy-metabolites and 3 ng/ml for imipramine and desipramine. The intra- and inter-day coefficients of variation at 50 ng/ml were 5.2% and 6.8%, respectively (n=8).

Imipramine metabolism in relation to the sparteine and mephenytoin oxidation polymorphisms--a population study.

1. Sparteine and mephenytoin phenotyping tests were carried out in 327 healthy Danish subjects. Two weeks later each subject took 25 mg imipramine followed by urine collection for 24 h. The urinary content of imipramine, desipramine, 2-hydroxy-imipramine and 2-hydroxy-desipramine was assayed by h.p.l.c. 2. The medians of the hydroxylation ratios (i.e. 2-hydroxy-metabolite over parent compound) were 6 to 14 times higher in 300 extensive metabolizers of sparteine (EMs) as compared with 27 poor metabolizers (PMs), but none of the ratios separated the two phenotypes completely. 3. There were 324 EM of mephenytoin (EMM) and three PM (PMM) in the sample. The demethylation ratios between desipramine, 2-hydroxy-desipramine and their corresponding tertiary amines showed statistically significant correlations with the mephenytoin S/R isomer ratio (Spearman's rs: -0.20 and -0.27, P < 0.05). 4. The demethylation ratios were higher in 80 smokers than in 245 non-smokers. This indicates that CYP1A2, which is induced by cigarette smoking, also catalyzes the N-demethylation of imipramine. 5. CYP2D6 genotyping was carried out by PCR in 325 of the subjects, and the D6-wt allele was amplified in 298 EMs, meaning that they were genotyped correctly. One PMs was D6-wt/D6-B, another PMs had the genotype D6-wt/ and hence both were misclassified as EMs. The remaining 25 PMs were D6-A/D6-B (n = 5), D6-B/ (n = 18) or D6-D/D6-D (no PCR amplification, n = 2).(ABSTRACT TRUNCATED AT 250 WORDS)

Simultaneous high-performance liquid chromatography-electrochemical detection determination of imipramine, desipramine, their 2-hydroxylated metabolites, and imipramine N-oxide in human plasma and urine: preliminary application to oxidation pharmacogenetics.

This assay method allows a simultaneous determination of imipramine, desipramine, their 2-hydroxylated metabolites, and imipramine-N-oxide in 0.5 ml of plasma or 0.1 ml of urine within 35 min by an ion-paired, reversed phase (C18) high-performance liquid chromatography (HPLC) with electrochemical detection. The analytes are extracted from alkalinized plasma or urine with 5 ml of a 90/10 mixture (by vol) of diethyl either/2-propanol, back-extracted into 0.5 ml of 0.1 mol/L phosphoric acid. Urine samples are enzymatically treated with beta-glucuronidase/arylsulfatase before extraction. The electrochemical detection is performed with a glassy carbon electrode set at +0.85 V against the Ag/AgCl reference electrode. Recoveries for the analytes and the internal standard (propericiazine) from plasma or urine ranged from 66.4 to 105.7% with coefficients of variation (CVs) of < 6.8%. The intra- and interassay CVs for the analytes were < 17.4% in plasma and < 14.2% in urine. The limits of determination (a signal-to-noise ratio of 3) for imipramine, desipramine, 2-hydroxyimipramine, 2-hydroxydesipramine, and imipramine-N-oxide were 0.5, 0.3, 0.02, 0.02, and 1.0 microgram/L, respectively. Only four of the 23 psychotropic drugs, which might be coadministered with imipramine or desipramine, were considered to be the possible sources to interfere with the assay. We evaluated clinical applicability of this method by determining plasma concentration- and urinary excretion-time courses of the respective analytes in an extensive and a poor metabolizer of the debrisoquine/sparteine-type oxidation after a single oral dose of imipramine HCl (25 mg). The present method appears to be suitable not only for the therapeutic drug monitoring of imipramine and its active metabolites but also for studying the pharmacogenetically related metabolism of imipramine or desipramine.

High-performance liquid chromatography of imipramine and six metabolites in human plasma and urine.

A method for the simultaneous quantitation of imipramine and six metabolites (2- and 10-hydroxyimipramine, 2- and 10-hydroxydesipramine, didesmethylimipramine and desipramine) in human plasma and urine has been developed. The method is based on a three-step liquid-liquid extraction followed by isocratic, reversed-phase high-performance liquid chromatography with ultraviolet absorbance detection (detection wavelength: 220 nm). The chromatographic eluent consisted of 30% acetonitrile and 70% aqueous sodium perchlorate solution pH 2.5. Glucuronide conjugates in urine were deconjugated with beta-glucuronidase/arylsulphatase prior to extraction.

Application of Empore C-8 extraction disks for screening urine in systematic toxicological analysis.

Solid-phase extraction (SPE) by means of disposable columns has become a widely accepted technique for sample pretreatment in toxicology, both for directed analyses and for screening analyses. However, the sample capacity in SPE is usually limited to a few millilitres. Therefore, we have investigated to what extent these problems can be overcome by using Empore extraction disks, consisting of chemically modified C-8 reversed-phase silica, embedded in an inert polytetrafluoroethylene (PTFE) matrix. Human urine was selected as the matrix and dexetimide and mepyramine were initially used as test drugs because these drugs were available in tritiated form. Additional drugs investigated included codeine, hexobarbital, imipramine, methamphetamine, and nitrazepam. In these investigations, the sample capacity for untreated urine was at least 25 mL, and analyte quantities up to 250 micrograms could be retained by these filters. Washing with water/methanol mixtures was successful in removing substantial amounts of endogenous interferences, and methanol proved to be an acceptable eluent. Thus, these disks seem to have interesting potential for toxicological analysis in that sample concentration and cleanup can be achieved at the same time.

Simultaneous determination of imipramine, desipramine and their deuterium-labelled analogues in biological fluids by capillary gas chromatography-mass spectrometry.

A specific, sensitive and accurate method for the determination of imipramine, desipramine and their d4 analogues in biological fluids using d8 analogues as internal standards using capillary gas chromatography-chemical ionization mass spectrometry was developed. Drug concentrations were measured by selected-ion monitoring of the quasi-molecular ions of imipramine and the trifluoro-acetyl derivative of desipramine. The coefficient of variation and relative error at a concentration of about 2 ng/ml in plasma were found less than 10% and 7%, respectively, for both drugs. No isotope effect was observed following the oral administration of an equimolar mixture of imipramine and [2H4]imipramine to a rat.

A sensitive colorimetric method for the determination of imipramine hydrochloride and desipramine hydrochloride.

A simple and rapid colorimetric method for the determination of imipramine hydrochloride and desipramine hydrochloride in their tablet formulations and in biological fluids is presented. The method is based on the reaction of these drugs with 3-methyl-2-benzothiazolone hydrazone in the presence of ferric chloride, with direct measurement at 635 nm. Cyclohexane was used to extract these drugs from serum and urine, at basic pH, by a single manual extraction. The method can detect 0.5 microgram/ml of each drug. The main advantages of this method are its simplicity and high sensitivity.