Chiral analysis of selected dopamine receptor antagonists in serum using capillary electrophoresis with cyclodextrin additives

Preparation and characterization of novel MWCNTs/Fe-Co doped TNTs nanocomposite for potentiometric determination of sulpiride in real water samples

Novel multiwalled carbon nanotubes/ Fe-Co doped titanate nanotubes nanocomposite (MWCNTs/Fe-Co doped TNTs) facilitated the charge transfer and enhanced sensitivity and selectivity. Herein, three novel modified carbon paste sensors (CPSs) based on MWCNTs (sensor I), Fe-Co doped TNTs (sensor II) and MWCNTs/Fe-Co doped TNTs composite (sensor III) were fabricated for a simple, low cost and high accuracy electrochemical method for the potentiometric determination of sulpiride (SLP). The sensors exhibited excellent Nernstian slopes 57.1 ± 0.4, 56 ± 0.5 and 58.8 ± 0.2 mV decade⁻¹ with detection limits (DL) 7.6 × 10⁻⁷, 1.58 × 10⁻⁶ and 8.7 × 10⁻⁸ mol L⁻¹, quantification limits (QL) 2.5 × 10⁻⁶, 5.2 × 10⁻⁶ and 2.9 × 10⁻⁷ mol L⁻¹ for a long lifetime 20, 18, and 25 weeks for sensors (I), (II), and (III), respectively. The modified sensor (III) was applicable by measuring the concentration of spiked SLP in pure solutions, pharmaceutical products, human urine, and real water samples. The proposed method can be used as an important analytical tool in the quality control of the pharmaceutical industry.

Quality by design in the chiral separation strategy for the determination of enantiomeric impurities: development of a capillary electrophoresis method based on dual cyclodextrin systems for the analysis of levosulpiride

Quality by design (QbD) concepts, in accordance with International Conference on Harmonisation Pharmaceutical Development guideline Q8(R2), represent an innovative strategy for the development of analytical methods. In this paper QbD principles have been comprehensively applied in the set-up of a capillary electrophoresis method aimed to quantify enantiomeric impurities. The test compound was the chiral drug substance levosulpiride (S-SUL) and the developed method was intended to be used for routine analysis of the pharmaceutical product. The target of analytical QbD approach is to establish a design space (DS) of critical process parameters (CPPs) where the critical quality attributes (CQAs) of the method have been assured to fulfil the desired requirements with a selected probability. QbD can improve the understanding of the enantioseparation process, including both the electrophoretic behavior of enantiomers and their separation, therefore enabling its control. The CQAs were represented by enantioresolution and analysis time. The scouting phase made it possible to select a separation system made by sulfated-β-cyclodextrin and a neutral cyclodextrin, operating in reverse polarity mode. The type of neutral cyclodextrin was included among other CPPs, both instrumental and related to background electrolyte composition, which were evaluated in a screening phase by an asymmetric screening matrix. Response surface methodology was carried out by a Doehlert design and allowed the contour plots to be drawn, highlighting significant interactions between some of the CPPs. DS was defined by applying Monte-Carlo simulations, and corresponded to the following intervals: sulfated-β-cyclodextrin concentration, 9-12 mM; methyl-β-cyclodextrin concentration, 29-38 mM; Britton-Robinson buffer pH, 3.24-3.50; voltage, 12-14 kV. Robustness of the method was examined by a Plackett-Burman matrix and the obtained results, together with system repeatability data, led to define a method control strategy. The method was validated and was finally applied to determine the enantiomeric purity of S-SUL in pharmaceutical dosage forms.

Development and Validation of a UPLC Method by the QbD-Approach for the Estimation of Rabeprazole and Levosulpiride from Capsules

Statistical experimental design was used to optimize the chromatographic separations of two pharmaceutical compounds from their respective potential impurities. A fractional factorial design was utilized to study the effects of pH, organic solvent in mobile phases A&B, and flow rate on the resolution of Rabeprazole and Rabeprazole Sulfone, which had closely eluting peaks. A desirability function applied to the optimized conditions predicted the peak resolution between 2.2 and 2.7 for the Rabeprazole & Rabeprazole Sulfone impurity. The chromatographic method employed an Acquity UPLC, BEH C18 column (100 × 2.1 mm i.d., 1.7 μm particle size) with the mobile phase consisting of a phosphate buffer, pH 6.5, and acetonitrile in a gradient program. The flow rate and injection volumes were 0.45 mL/min & 5 μl, respectively, and detection was done at 254 nm. The chromatographic method was validated for linearity, accuracy, precision, specificity, and ruggedness according to ICH guidelines. The results clearly showed that the quality by design concept could be effectively applied to optimize a UPLC chromatographic method with fewer trials and error-free experimentation.

Synthesis, spectroscopic and thermal characterization of sulpiride complexes of iron, manganese, copper, cobalt, nickel, and zinc salts. Antibacterial and antifungal activity

Sulpiride (SPR; L) is a substituted benzamide antipsychotic which is reported to be a selective antagonist of central dopamine receptors and claimed to have mood-elevating properties. The ligation behaviour of SPR drug is studied in order to give an idea about its potentiality towards some transition metals in vitro systems. Metal complexes of SPR have been synthesized by reaction with different metal chlorides. The metal complexes of SPR with the formula [MCl(2)(L)(2)(H(2)O)(2)].nH(2)O [M=Mn(II), Co(II), Ni(II), Cu(II) and Zn(II); n=0-2] and [FeCl(2)(HL)(H(2)O)(3)]Cl.H(2)O have been synthesized and characterized using elemental analysis (CHN), electronic (infrared, solid reflectance and (1)H NMR spectra) and thermal analyses (TG and DTA). The molar conductance data reveal that the bivalent metal chelates are non-electrolytes while Fe(III) complex is 1:1 electrolyte. IR spectra show that SPR is coordinated to the metal ions in a neutral monodentate manner with the amide O. From the magnetic and solid reflectance spectra, octahedral geometry is suggested. The thermal decomposition processes of these complexes were discussed. The correlation coefficient, the activation energies, E*, the pre-exponential factor, A, and the entropies, DeltaS*, enthalpies, DeltaH*, Gibbs free energies, DeltaG*, of the thermal decomposition reactions have been derived from thermogravimetric (TG) and differential thermogravimetric (DTG) curves. The synthesized ligand and its metal complexes were also screened for their antibacterial and antifungal activity against bacterial species (Escherichia coli and Staphylococcus aureus) and fungi (Aspergillus flavus and Candida albicans). The activity data show that the metal complexes are found to have antibacterial and antifungal activity than the parent drug and less than the standard.

Two charge-transfer complex spectrophotometric methods for the determination of sulpiride in pharmaceutical formulations

Two simple, rapid, accurate and sensitive spectrophotometric methods are described for the determination of sulpiride. They are based on charge transfer complexation between the drug as n-electron donor and p-chloranilic acid as π acceptor or iodine as σ-acceptor. These give highly coloured complexes with absorption maxima at 518 and 363, 294 nm, respectively. Beer’s law linear ranges were 13.7–341.4 and 1.7–20.5 µg mL−1 for the p-chloranilic acid and iodine methods. The methods were successfully applied to the determination of the drug in Dogmatil® Fort tablets and the results compared with the official method. The complex association constants and standard free energy changes were calculated using Benesi-Hildebrand plots.

Development of membrane selective electrode for determination of the antipsychotic sulpiride in pharmaceuticals and urine

The construction and electrochemical response characteristics of a poly(vinyl chloride) (PVC) membrane selective electrode for the determination of sulpiride (SPD) are described. The sensing membrane comprised an ion-exchanger formed between the protonated drug and tetraphenylborate (TPB(-)) in a plasticized PVC matrix. The influence of membrane composition on the electrode response was studied. The electrode showed a fast, stable and Nernstian response over a sulpiride concentration range (1 × 10(-4) - 1 × 10(-2) M) with a mean slope of 58.4 ± 0.9 mV dec(-1) of concentration, a mean detection limit of 4.2 × 10(-5) ± 1.2 × 10(-5) M, a wide working pH range (2 - 8) and a fast response time (< 15 s). The electrode showed good selectivity towards sulpiride with respect to some inorganic and organic compounds. When the electrode was applied to the determination of sulpiride in pharmaceuticals and human urine, a high percentage of recovery was attained with no need for sample pretreatment procedures because of the lack of interfering matrix effects.

Electrochemical Behavior of Dopamine at a Penicillamine Self-Assembled Gold Electrode and its Analytical Application

The fabrication and electrochemical characteristics of penicillamine (PCA) self-assembled monolayer modified gold electrode were investigated. The self-assembled electrode shows an obvious electrocatalytic activity for the oxidation of dopamine (DA). In phosphate buffer (pH 7.0), the peak current is proportional to the concentration of DA in the range of 8.0 x 10(-6) approximately 1.0 x 10(-3) M by the cyclic voltammetry methods with the detection limits of 4.5 x 10(-7) M. The PCA self-assembled monolayer modified gold electrode can be applied to the determination of DA in practical injection samples with simplicity, rapidness, and accurate results.

Simultaneous electrochemiluminescence determination of sulpiride and tiapride by capillary electrophoresis with cyclodextrin additives

Sulpiride and tiapride are often used in the treatment of depression, schizophrenia and psychopathology of senescence, gastric or duodenal ulcers and are also partly excreted by kidney. This work developed a simple and sensitive method for their simultaneous monitoring in human urine based on capillary electrophoresis coupled with electrochemiluminescence detection by end-column mode. beta-Cyclodextrin (beta-CD) was used as an additive to the running buffer to obtain the absolute separation of sulpiride and tiapride. Under optimized conditions the proposed method displayed a linear range from 1.0 x 10(-7) to 1.0 x 10(-4) M for both sulpiride and tiapride with the correlation coefficients more than 0.995 (n = 6). Their limits of detection were 1.0 x 10(-8) M (45 amol) and 1.5 x 10(-8) M (68 amol) at a signal to noise ratio of 3, respectively. The relative standard deviations for six determinations of 2.0 microM sulpiride and 3.0 microM tiapride were 1.8 and 2.5%, respectively. For practical application an extract step with ethyl acetate at pH 11 was performed to eliminate the influence of ionic strength in sample. The recoveries of sulpiride and tiapride at different levels in human urine were between 84 and 95%, which showed that the method was valuable in clinical and biochemical laboratories for monitoring sulpiride and tiapride for various purposes.

Simultaneous Determination of Mebeverine Hydrochloride and Sulpiride Using the First Derivatives of Ratio Spectra and Chemometric Methods

Two methods are described for the simultaneous determination of mebeverine hydrochloride (MB) and sulpiride (SU) in their combinations. The first method depends on the first derivative of the ratio spectra by measurement of the amplitudes at 263.7 and 234.9 nm for MB and SU, respectively. The linear ranges and detection limits are 4.0-40.0 and 0.72 microg/ml for MB and 1.0-10.0 and 0.34 microg/ml for SU. In the second case, a chemometric (classical least squares) method was developed. The concentration data matrices were obtained by using different concentrations of pure drugs in 0.1 M HCl. The absorbance data matrix corresponding to each concentration data matrix was obtained by the measurements of absorbances in the range 200-300 nm in their zero order spectra; then calibration was obtained by using the absorbance data matrix and the concentration data matrix for the prediction of the unknown concentrations of MB and SU in their mixture. The numerical values were calculated by using Matlab R12 version 6.0 and Origin 5.0 software. The procedures do not require any separation steps. These two methods were successfully applied for assaying the pharmaceutical formulation, of Colona tablets.

Development of HPLC method for the determination of levosulpiride in human plasma

A rapid and simple high performance liquid chromatography (HPLC) method was developed and validated for determination of levosulpiride in human plasma. After extraction with ethylacetate/methylene chloride (5:1, v/v), analysis of levosulpiride in plasma samples was carried out using a reverse phase C18 column with fluorescence detector (maximum excitation at 300 nm and maximum emission at 365 nm) for separation and quantification. A mixture of methanol-20 mM phosphate buffer (pH 3.5, 16:84, v/v) was used as a mobile phase. The method was specific and sensitive with a limit of quantification of 5 ng/ml. This HPLC method was validated by examining the precision and accuracy for inter- and intra-day analysis in the concentration range of 5-150 ng/ml. The relative standard deviation (R.S.D.) in inter- and intra-day validation were 8.16-19.75 and 3.90-11.69%, respectively. In stability tests, levosulpiride in human plasma was stable during the storage and assay procedure. The method was applied to the bioequivalence study of two levosulpiride tablet formulations (25 mg) after a single oral administration.

Comprehensive strategy for chiral separations using sulfated cyclodextrins in capillary electrophoresis

This review focuses on the emerging role of sulfated cyclodextrins in the capillary electrophoretic (CE) separation of chiral analytes. Since being introduced as enantioselective agents for CE in 1995, these anionic additives have continued to demonstrate remarkable application universality. The broad spectrum of chiral compounds successfully separated using this approach includes acidic, basic, neutral, and zwitterionic species. This impressive array of analyte structures is derived from a growing diversity of compound classes including pharmaceuticals, plant extracts, biomarkers, herbicides, alkaloids, fungicides, and metal ions. Moreover, literature reports highlight the minimal optimization required to achieve a successful separation. Based on these findings, sulfated cyclodextrins appear to be well suited for the development of a more universal, comprehensive separation strategy for chiral compounds. This review explores this proposition by beginning with the structure and migration properties of sulfated cyclodextrins, using applications to highlight the separating power of this technique and ending with a pragmatic, comprehensive separation strategy.

Quantitative bioanalysis of enantiomeric drugs using capillary electrophoresis and electrospray mass spectrometry

A novel assay method for an enantiomeric pair of drugs has been developed using a combination of capillary electrophoresis and electrospray tandem mass spectrometry connected with a homemade interface. Accurate quantification was demonstrated in plasma from 0.25 to 50 microg/ml. A liquid-liquid sample preparation technique allowed improvement in the quantitation limit to 10 ng/ml. Variables for the enantiomeric separation, including chiral selective reagent, organic solvents, buffer and acid concentration as well as injection technique, were optimized. This assay proved adequate for analysis of neat, spiked plasma, and plasma from a pharmacological study of the drug enantiomers.

The use of a highly sulfated cyclodextrin for the simultaneous chiral separation of amphetamine-type stimulants by capillary electrophoresis

We investigated the simultaneous chiral separation of nine amphetamine type stimulants (dl-norephedrine, dl-norpseudoephedrine, dl-ephedrine, dl-pseudoephedrine, dl-amphetamine, dl-methamphetamine, dl-methylenedioxyamphetamine (MDA), dl-methylenedioxymethamphetamine (MDMA), and dl-methylenedioxyethylamphetamine (MDEA)) by capillary electrophoresis using highly sulfated gamma-cyclodextrin (SU(XIII)-gamma-CD) as a chiral selector. Three different approaches using SU(XIII)-gamma-CD with 50 mM phosphate background electrolyte were designed; (I) high CD concentration (10 mM SU(XIII)-gamma-CD) at neutral pH (pH 7.0) in the normal polarity mode, (II) low CD concentration (1.0 mM) at low pH (pH 2.6) in the normal polarity mode and (III) high CD concentration at low pH (pH 2.6) in the reversed-polarity mode. In mode (II), the effects of adding three neutral CDs (beta-CD, dimethyl-beta-CD and hydroxypropyl-beta-CD) were also investigated. The best separation was obtained after optimizing mode (III) as follows: run buffer of 10 mM SU(XIII)-gamma-CD with 50 mM phosphate background electrolyte at pH 2.6, applied voltage of -12 kV and capillary temperature of 15 degrees C.

Selected fundamental aspects of chiral electromigration techniques and their application to pharmaceutical and biomedical analysis

While capillary electrophoresis has been established as a major enantioseparation technique within the last decade, the potential of capillary electrochromatography is still studied extensively. This review summarizes recent applications of electromigration techniques with regard to the enantioseparation of chiral drugs. The first part discusses the general aspects of migration models and the enantiomer migration order. The application of capillary electrophoresis to chiral pharmaceutical analysis considers recent literature on: (1) chiral resolutions of non-racemic mixtures of enantiomers for the development of assays and the determination of the stereochemical purity of the drugs, (2) chiral separations of compounds in pharmaceutical formulations and products, and (3) enantioseparations of drugs in biological samples. A shorter section devoted to chiral electrochromatography discusses some fundamental aspects as well as the application to the chiral analysis of drugs including bioanalysis.