Method for simultaneous determination of eight cyclic antidepressants by cyclodextrin-modified capillary zone electrophoresis: applications in pharmaceuticals

Distinctive Supramolecular Features of β-Cyclodextrin Inclusion Complexes with Antidepressants Protriptyline and Maprotiline: A Comprehensive Structural Investigation

Depression, a global mental illness, is worsened due to the coronavirus disease 2019 (COVID-2019) pandemic. Tricyclic antidepressants (TCAs) are efficacious for the treatment of depression, even though they have more side effects. Cyclodextrins (CDs) are powerful encapsulating agents for improving molecular stability, water solubility, and lessening the undesired effects of drugs. Because the atomic-level understanding of the β-CD–TCA inclusion complexes remains elusive, we carried out a comprehensive structural study via single-crystal X-ray diffraction and density functional theory (DFT) full-geometry optimization. Here, we focus on two complexes lining on the opposite side of the β-CD–TCA stability spectrum based on binding constants (K_as) in solution, β-CD–protriptyline (PRT) 1—most stable and β-CD–maprotiline (MPL) 2—least stable. X-ray crystallography unveiled that in the β-CD cavity, the PRT B-ring and MPL A-ring are aligned at a nearly perfect right angle against the O4 plane and primarily maintained in position by intermolecular C–H···π interactions. The increased rigidity of the tricyclic cores is arising from the PRT -CH=CH- bridge widens, and the MPL -CH₂–CH₂- flexure narrows the butterfly angles, facilitating the deepest and shallower insertions of PRT B-ring (1) and MPL A-ring (2) in the distorted round β-CD cavity for better complexation. This is indicated by the DFT-derived complex stabilization energies (ΔE_stbs), although the complex stability orders based on K_as and ΔE_stbs are different. The dispersion and the basis set superposition error (BSSE) corrections were considered to improve the DFT results. Plus, the distinctive 3D arrangements of 1 and 2 are discussed. This work provides the first crystallographic evidence of PRT and MPL stabilized in the β-CD cavity, suggesting the potential application of CDs for efficient drug delivery.

A novel MIP-ECL sensor based on RGO-CeO2NP/Ru(bpy)32+-chitosan for ultratrace determination of trimipramine

A novel molecularly imprinted polymer (MIP)-electrochemiluminescence (MIP-ECL) sensor based on CeO2NP-RGO/Ru(bpy)32+-MIP-chitosan was introduced for the ultrasensitive and ultraselective detection of trimipramine (TRI). TRI-MIP was synthesized via the precipitation polymerization process. A nanocomposite of reduced graphene oxide decorated with ceria (CeO2NP-RGO) was synthesized through a facile sonochemical process. CeO2NP-RGO was utilized for modifying the surface of an electrode which consequently led to an excellent electrical conductivity, enhanced electrochemical and ECL characteristics of Ru(bpy)32+. Electrochemical and ECL behaviors of the MIP-ECL sensor were evaluated. Accordingly, the ECL intensity was significantly enhanced via TRI molecule adsorption on the MIP composite film. The prepared MIP-ECL sensor demonstrated high sensitivity and selectivity as well as good reproducibility and stability for TRI determination under the applied optimal conditions. The assays response for TRI concentration was linear in the range of 0.2-100 pM with a 0.995 correlation coefficient. The limit of detection (LOD) was as small as 0.025 pM (S/N = 3). The recoveries between 91-107% for human serum (RSDs < 4.1%) and 94-104.6% for human urine (RSDs < 3.4%) approve that the MIP-ECL sensor can be used for precise detection of TRI in complex biological matrices. Ultimately, this sensor was utilized successfully for the analysis of TRI in human serum and urine samples without any special pretreatment.

Terbium(iii)-coated carbon quantum dots for the detection of clomipramine through aggregation-induced emission from the analyte

CQD-Tb: a selective chemosensor for detecting the antidepressant drug clomipramine in aqueous media.

Quality by Design approach in the development of a solvent-modified micellar electrokinetic chromatography method: finding the design space for the determination of amitriptyline and its impurities

A solvent-modified micellar electrokinetic chromatography method was set up for the simultaneous determination of the tricyclic antidepressant amitriptyline (AMI) and its main impurities. The method was developed following Quality by Design (QbD) principles according to ICH Guideline Q8(R2). QbD approach made it possible to find the design space (DS), where quality was assured. After a scouting phase, aimed at selecting a suitable capillary electrophoresis pseudostationary phase, risk assessment tools were employed to define the critical process parameters (CPPs) to be considered in a screening phase (applied voltage, concentration and pH of the background electrolyte, concentration of the surfactant sodium dodecyl sulphate, of the cosurfactant n-butanol and of the organic modifiers acetonitrile and urea). The effects of the seven selected CPPs on critical quality attributes (CQAs), namely resolution values between critical peak pairs and analysis time, were investigated throughout the knowledge space by means of a symmetric screening matrix. Response surface study was then carried out on four selected CPPs by applying a Doehlert Design. Monte-Carlo simulations were performed in order to estimate the probability of meeting the desired specifications on CQAs, and thus to define the DS by means of a risk of failure map. Additional points at the edges of the DS were tested in order to verify the requirements for CQAs to be fulfilled. A control strategy was implemented by defining system suitability tests. The developed method was validated following ICH Guideline Q2(R1), including robustness assessment by Plackett-Burman design, and was applied to the analysis of real samples of amitriptyline coated tablets.

Liquid three-phase microextraction based on hollow fiber for highly selective and sensitive determination of using an ion selective electrode

In this paper, for the first time, a combination of hollow fiber based liquid 3-phase microextraction with a potentiometric method was applied as a highly selective and sensitive method of analysis. Desipramine, as a model compound, was extracted from a small volume in the presence of 0.10 mol L-1 NaOH (donor solution) through a thin phase of propyl benzoate inside the pores of a polypropylene hollow fiber and finally into a 10 μL acidic acceptor solution inside the hollow fiber. Two microelectrodes were designed and inserted into the two ends of a hollow fiber inside the acceptor solution. Potentiometric analysis was performed in situ within an extraction time of 15 min; the final stable signal was used for analytical application. Under the optimized conditions, an enrichment factor of 296 was achieved and the relative standard deviation (RSD%) of the method was 4.5%. The calibration curve was obtained in the range of 3.0 × 10-5 to 3.4 × 10-8 mol L-1 with a reasonable linearity (R2 > 0.9849) and a limit of detection (LOD) of 3.1 × 10-8 mol L-1. Finally, the applicability of the proposed method was evaluated by extraction and determination of desipramine in plasma and urine samples without any special pretreatment.

A novel electrochemical sensor for probing doxepin created on a glassy carbon electrode modified with poly(4-amino- benzoic acid)/multi-walled carbon nanotubes composite film

A novel electrochemical sensor for sensitive detection of doxepin was prepared, which was based on a glassy carbon electrode modified with poly(4-aminobenzoic acid)/multi-walled carbon nanotubes composite film [poly(4-ABA)/MWNTs/GCE]. The sensor was characterized by scanning electron microscopy and electrochemical methods. It was observed that poly(4-ABA)/MWNTs/GCE showed excellent preconcentration function and electrocatalytic activities towards doxepin. Under the selected conditions, the anodic peak current was linear to the logarithm of doxepin concentration in the range from 1.0 × 10⁻⁹ to 1.0 × 10⁻⁶ M, and the detection limit obtained was 1.0 × 10⁻¹⁰ M. The poly(4-ABA)/MWNTs/GCE was successfully applied in the measurement of doxepin in commercial pharmaceutical formulations, and the analytical accuracy was confirmed by comparison with a conventional ultraviolet spectrophotometry assay.

Analysis of tricyclic antidepressant drugs in plasma by means of solid-phase microextraction-liquid chromatography-mass spectrometry

Solid-phase microextraction coupled to liquid chromatography and mass spectrometry (SPME-LC-MS) was used to analyze tricyclic antidepressant drugs desipramine, imipramine, nortriptyline, amitriptyline, and clomipramine (internal standard) in plasma samples. SPME was performed by direct extraction on a PDMS/DVB (60 microm) coated fiber, employing a stirring rate of 1200 rpm for 30 min, pH 11.0, and temperature of 30 degrees C. Drug desorption was carried out by exposing the fiber to the liquid chromatography mobile phase for 20 min, using a labmade SPME-LC interface at 50 degrees C. The main variables experimentally influencing LC-MS response were evaluated and mathematically modeled. A rational optimization with fewer experiments was achieved using a factorial design approach. The constructed empirical models were adjusted with 96-98% of explained deviation allowing an adequate data set comprehension. The chromatographic separation was realized using an RP-18 column (150 mm x 2.1 mm, 5 microm particles) and ammonium acetate buffer (0.01 mol/l, pH 5.50) : acetonitrile (50 : 50 v/v) as mobile phase. Low detection levels were achieved with electrospray interface (0.1 ng/ml). The developed method showed specificity, linearity, precision, and limit of quantification adequate to assay tricyclic antidepressant drugs in plasma.

Simultaneous determination of psychotropic drugs in human urine by capillary electrophoresis with electrochemiluminescence detection

Amitriptyline, doxepin and chlorpromazine are often used as psychotropic drugs in treatment of the various mental diseases, and are also partly excreted by kidney. This work developed a simple, selective and sensitive method for their simultaneous monitoring in human urine using capillary electrophoresis coupled with electrochemiluminescence (ECL) detection based on end-column ECL reaction of tris-(2,2'-bipyridyl)ruthenium(II) with aliphatic tertiary amino moieties. Acetone was used as an additive to the running buffer to obtain their absolute separation. Under optimized conditions the proposed method displayed a linear range from 5.0 to 800 ng mL(-1) for the three drugs with the correlation coefficients more than 0.995 (n=8). Their limits of detection were 0.8 ng mL(-1) (3.6 fg), 1.0 ng mL(-1) (4.5 fg) and 1.5 ng mL(-1) (6.8 fg) at a signal to noise ratio of 3, respectively. The relative standard deviations for five determinations of 20 ng mL(-1) amitriptyline, doxepin and chlorpromazine were 1.7%, 4.2% and 3.6%, respectively. For practical application an extract step with 90:10 heptane/ethyl acetate (v/v) was performed to eliminate the influence of ionic strength in sample. The recoveries of amitriptyline, doxepin and chlorpromazine at different levels in human urine were between 83% and 93%, which showed that the method was valuable in clinical and biochemical laboratories for monitoring amitriptyline, doxepin and chlorpromazine.

Determination of antidepressants in surface and waste water samples by capillary electrophoresis with electrospray ionization mass spectrometric detection after preconcentration using off-line solid-phase extraction

A method for the quantitative determination of seven major antidepressants in surface waters and sewage treatment plant effluents by CE using ESI-MS is presented. Calibration curves for the selected analytes were prepared in Milli-Q purified water and Danube river water extract covering a concentration range of at least one order of magnitude. LODs achieved were between 6 and 13 microg/L for Trazodone and 39 and 53 microg/L for Sertraline in the Milli-Q purified water and Danube river water matrix, respectively. For sample preparation eight different SPE materials were investigated. Best results were obtained for a resin based on hydrophilic divinylbenzene (recoveries from Milli-Q purified water 93-96%; from Danube river water 85-99%). Finally, a series of eight sewage treatment plant effluents were investigated with respect to their content in the selected antidepressants. Six of these samples were tested positive for antidepressants, in particular Venlafaxine, Citalopram and Trazodone in concentrations between 36 and 322 ng/L.

Using of S-(-)-2-hydroxymethyl-1,1-dimethylpyrrolidinium tetrafluoroborate as additive to the background electrolyte in capillary electrophoresis

We synthesised and used new type of quaternary ammonium salt [S-(-)-2-hydroxymethyl-1,1-dimethylpyrrolidinium tetrafluoroborate] as effective additive to acidic background electrolytes. We used this quaternary ammonium salt as effective agent for capillary zone electrophoresis separation of model mixture of five tricyclic antidepressants (amitriptyline, nortriptyline, imipramine, desipramine and clomipramine) as model analytes. We observed that addition of S-(-)-2-hydroxymethyl-1,1-dimethylpyrrolidinium tetrafluoroborate ([HMDP](+) [BF(4)](-)) to acidic background electrolytes leads to suppression of magnitude of electroosmotic flow (EOF) and gradually change the direction of the EOF. Baseline separation of five TAs was achieved by using of 91.1 mmol L(-1) (20 gL(-1)) of [HMDP](+) [BF(4)](-) in 25 mmol L(-1) sodium phosphate pH 2.5, where electroosmotic mobility was -11.3 x 10(-9) m(2) V(-1) s(-1). We achieved baseline separation of five TAs with using of [HMDP](+) [BF(4)](-) as water solution too. We observed that [HMDP](+) [BF(4)](-) can be used as buffer additive, which offers relatively smaller anodic electroosmotic flow instead of cationic surfactants that are mostly used for genarating of anodic electroosmotic flow in capillary electrophoresis.

Development of an analytical method for the determination of antidepressants in water samples by capillary electrophoresis with electrospray ionization mass spectrometric detection

A method for the quantitative determination of major antidepressants in aqueous matrices by CE using ESI-MS is presented. Several aqueous, nonaquoeus, and mixed aqueous/organic solvent BGEs including inorganic and organic acids were investigated with respect to their suitability for the separation of the selected analytes. Finally, due to the necessity to employ MS detection if the developed method should be suitable also for environmental samples, only MS-compatible electrolytes were taken into account. Based on this fact optimum results were obtained with a system consisting of 1.5 M formic acid and 50 mM ammonium formate in ACN/water (85/15). Linear calibration plots could be obtained for all solutes over a concentration range of almost two orders of magnitude, and the LODs achieved were in the range of 3-6 microg/L for trazodone and 39-43 microg/L for sertraline with the TOF instrument and the single quadrupole instrument in the SIM mode, respectively. This fact allowed the assumption that the presented method can be regarded as suitable for the determination of antidepressants even in the trace amounts commonly present in environmental samples. Spiking of river water and sewage plant effluent extracts with the selected solutes showed that no interferences from the matrix usually found in such samples can be expected. Finally the quantitative determination of the seven antidepressants in environmental samples was used to benchmark the performance of CZE coupled to a single quadrupole MS and a TOF-MS.