A high-performance liquid chromatographic method was developed for the simultaneous determination of the related substances-three potential synthesis-related chemical impurities and the distomer-of ...escitalopram. The separation capacity of seven different polysaccharide-type chiral columns, including three amylose-based (Lux Amylose-1, Lux i-Amylose-1, Lux Amylose-2) and four cellulose-based columns (Lux Cellulose-1, Lux Cellulose-2, Lux Cellulose-3, and Lux Cellulose-4) were screened in the polar organic and reversed-phase modes. Lux Cellulose-1, based on cellulose tris(3,5-dimethylphenylcarbamate) as the chiral selector with an acetonitrile-water mixture containing 0.1% diethylamine was identified as the most promising separation system. Using the "one factor at a time" optimization approach, the effect of column temperature, flow rate, and mobile phase constituents on separation performance was evaluated, and the critical resolution values were determined. A U-shaped retention pattern was obtained when plotting the retention factors of the citalopram enantiomers versus the water content of the binary mobile phases on the Lux Cellulose-1 column. A thermodynamic analysis revealed enthalpy-driven enantioseparation in both the polar organic and reversed-phase modes. For further method optimizations, an L9 orthogonal array table was employed. Using the optimized parameters (Lux Cellulose-1 column with 0.1% (
/
) diethylamine in water/acetonitrile 55/45 (
/
); 0.8 mL/min flow rate at 25 °C), baseline separations were achieved between all compounds. Our newly developed HPLC method was validated according to the ICH guidelines and its application was tested with a commercially available pharmaceutical formulation. The method proved to be suitable for routine quality control of related substances and the enantiomeric purity of escitalopram.
A new, reversed-phase HPLC (RP-HPLC) method was developed for the simultaneous determination of the dipeptidyl-peptidase-IV-inhibitor antidiabetic drug vildagliptin (VIL) enantiomeric impurity and ...four other achiral related impurities. An initial screening was performed on five polysaccharide-type chiral stationary phases (Lux Amylose-1, Lux Amylose-2, Lux-Cellulose-1, Lux-Cellulose-2, Lux-Cellulose-3) in polar organic mode with methanol, ethanol, 2-propanol, or acetonitrile containing 0,1% diethylamine as mobile phase to identify the best conditions for the separation of VIL enantiomers. Lux-Cellulose-2 column was found to provide the best chiral resolution for VIL enantiomers. Further experiments were conducted using different aqueous-organic mobile phases to achieve the simultaneous chiral-achiral separation of the selected compounds. Experimental design-based optimization was performed by using a face-centered central composite design. The optimal separation conditions (Lux Cellulose-2 stationary phase, 45 °C, mobile phase consisting of methanol/water/diethylamine 80:20:0.2 (v/v/v), and 0.45 mL/min flow rate) provided baseline separation for all 6 compounds. The optimized method was validated according to the ICH guideline and proved to be reliable, specific, linear, precise, and accurate for the determination of at least 0.1% for all impurities in VIL samples. The validated method was applied for determinations from a commercially available drug formulation and proved to be suitable for routine quality control of both enantiomeric and organic impurities of VIL.
•Enantiomeric separation of vildagliptin using Lux-Cellulose-2 column.•First published method for the simultaneous quantification of vildagliptin chiral and achiral impurities.•Method optimization based on response surface methodology.•Applicability in routine quality control of drug products.
An amorphous fiber-based solid dispersion of chlorzoxazone was prepared for the first time by employing centrifugal spinning, using polyvinylpyrrolidone as the fiber-forming polymer. After ...optimization of the spinning parameters, the obtained fibers were characterized using a set of analytical techniques, both in a solid- and solution-state. Morphological characterization revealed a slightly aligned, defect-free fibrous structure with an average fiber diameter of d = 3.07 ± 1.32 μm. The differential scanning calorimetric results indicated a crystalline-to-amorphous transition of the active substance during the centrifugal spinning process, while gas chromatographic determinations revealed a residual ethanol content of 0.42 ± 0.04%. UV spectroscopy indicated the incorporation of chlorzoxazone in the fibrous structures, with an average active substance content of 15.91 ± 0.36
/
%. During small-volume dissolution studies, the prepared fiber mats presented immediate disintegration upon contact with the dissolution media, followed by rapid dissolution of the active substance, with 84.8% dissolved at 1 min and 93.7% at 3 min, outperforming the micronized, pure chlorzoxazone. The obtained results indicate that centrifugal spinning is a low-cost, high-yield, viable alternative to the currently used methods to prepare fiber-based amorphous solid dispersions of poorly soluble drugs. The prepared chlorzoxazone-loaded microfibers could be used as a buccal dosage form for the systematic delivery of chlorzoxazone and could potentially lead to a rapid onset of action and longer efficacy of the muscle relaxant drug.
•Enantioseparation of oxazolidinones on polysaccharide-type CSP in polar organic mode•Selector-, immobilization- and eluent-dependent reversals of EEO•Hysteresis of retention and selectivity on ...amylose columns in different eluent mixtures•Different conformations of amylose selectors can be used for fine-tuning separations
The enantioseparation of four oxazolidinone and one biosimilar thiazolidine derivatives was performed on seven different polysaccharide-type chiral stationary phases (Lux Amylose-1, Lux i-Amylose-1, Lux Amylose-2, Lux Cellulose-1, Lux Cellulose-2, Lux Cellulose-3, Lux Cellulose-4) differing in backbone (cellulose or amylose), substituent or the immobilization technologies (coated or immobilized). Polar organic mode was employed using neat methanol (MeOH), ethanol (EtOH), 2-propanol (IPA) and acetonitrile (ACN) either alone or in combinations as mobile phases. Amylose-based columns with ACN provided the highest enantioselectivities for the studied compounds. The replacement of an oxygen with a sulfur atom in the backbone of the studied analytes significantly alters the enantiomer recognition mechanism. Chiral selector-, mobile-phase-, and interestingly immobilization-dependent enantiomer elution order reversal was also observed. Reversal of elution order and hysteresis of retention and enantioselectivity was further investigated using different mixtures of IPA:MeOH and ACN:MeOH on amylose-type chiral stationary phases. Hysteresis of retention and enantioselectivity was observed on all investigated amylose-type columns and binary eluent mixtures, which can be further utilized for fine-tuning chiral separation performance of the studied columns.
Aceclofenac-loaded polyvinylpyrrolidone fiber-based amorphous solid dispersion was produced successfully by centrifugal spinning. The solution concentration and rotational speed were optimized to ...produce the fiber-based drug carrier system, with a determined production rate of 12.7 g/h dry solid fibers. The obtained fibers were bead-free and smooth-surfaced with an average diameter of 7.5 ± 2.5 μm. Gas chromatographic determinations revealed that ethanol, as a residual solvent, was well below the regulatory limit of 0.5%. Differential scanning calorimetric investigation and infrared spectroscopic measurements were used to track the physicochemical changes that intervene during fiber formation in the solid state. The results revealed that the rapid evaporation of the solvent was accompanied by a probable crystalline to amorphous transition of the active substance during centrifugal spinning. In vitro dissolution studies revealed an instantaneous disintegration of the fibrous structure and a rapid release of the active substance, with the microfibrous webs greatly outperforming the crystalline active substance, especially in the early time-points. This implies that centrifugal spinning offers a viable scale-up production process to prepare drug-loaded fiber-based solid dispersions.
Lapatinib (Lap) is a lypophilic drug frequently used in cancer treatment; however, due to its limited solubility and permeability, achieving therapeutic dose through oral administration proves to be ...a challenge. There are various methods for enhancing the solubility of Lap and other similar drugs, one being the preparation of amorphous solid dispersions (ASD). In this study, a Lap-loaded polyvinylpyrrolidone (PVP) fiber mat was created with centrifugal spinning from a PVP/Lap solution in dimethyl formamide and ethanol. The production rate was 12.2 g/h dry fibers, and the fibers had an average thickness of 2.55 ± 0.92 μm. In the differential scanning calorimetry (DSC) thermogram of the fiber mat, the melting peak of the crystalline Lap was not visible, suggesting that Lap was in an amorphous state. A dissolution study was carried out in 0.2 M phosphate buffer saline solution at 37 °C. UV spectrophotometry data indicated that in the sample containing the fiber mat, the Lap concentration was 332 μg/mL (66%) in 10 min, decreasing to 227 μg/mL by 45 min. Meanwhile the crystalline Lap formed a 30-40 μg/mL (6-8%) solution in 5 min, maintaining that concentration. We conclude that centrifugal spinning can be an effective and easy method to produce ASDs.
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•Computer aided chromatographic method development for the simultaneous determination of albendazole and its related substances.•Optimization was realized using experimental ...design-based approach.•Alternative to replace an underperforming European Pharmacopoeia method.•In silico robustness testing and retention modelling performed by DryLab software.•After validation, method applicability was tested on commercial tablet formulation.
Computer-aided ultrahigh performance liquid chromatographic (UHPLC) method development and optimization was undertaken in order to replace an underperforming European Pharmacopoeia method for the determination of albendazole and its related substances. In the preliminary screening, a temperature-gradient time bidimensional model was chosen to aid selection of the proper stationary phase. Hereinafter temperature-gradient time-ternary composition and temperature-gradient time-pH tridimensional models were applied for the optimization of critical method parameters. The simulation and in silico robustness testing were realized using DryLab modeling software. The final method was validated for quantification of impurities and assay of the active substance according to the current ICH guidance. The validated methods were tested on a real, commercial tablet formulation. The experimental design-based and software-assisted method development proved to be a fast and reliable way of replacing a method with inadequate selectivity and long runtime with a robust UHPLC-based method, which offers baseline separation for all monitored impurities in 10 min. Results confirm that software-based chromatographic modelling can not only speed up the analytical method development process, but also improve the reliability of the developed method.
Enantioseparation of an anti-psoriatic agent, apremilast (APR), was performed by HPLC using polysaccharide-type chiral stationary phases in polar organic mode for the first time. The separation ...capability of six different chiral columns (Chiralpak AD, Chiralpak IA, Chiralpak AS, Lux Amylose-2, Chiralcel OD and Chiralcel OJ-H) was investigated using neat MeOH and ACN. During the preliminary experiments the best results were obtained on Chiralpak IA column with ACN (
R
s
= 5.4). The effects of binary mobile phases on the resolutions and retention factors were also investigated containing different percentages of MeOH:ACN. U-shaped retention pattern was obtained when plotting the retention factors of the APR enantiomers versus the MeOH content of the binary mobile phases on Chiralpak IA column. For further method optimizations an L25 orthogonal array table was employed altering the concentration of MeOH in ACN, column temperature, and flow rate. The best result was achieved on Chiralpak IA column with 80/20 (v/v%) MeOH/ACN with 0.7 mL min
−1
flow rate at 25 °C (
R
s
= 5.4,
t
2
= 7.45 min). Thermodynamic analysis revealed an enthalpy-driven enantioseparation. The developed HPLC method was validated according to the ICH guideline Q2(R1) and proved to be reliable, linear, precise and accurate for the determination of 0.1%
R
-enantiomer as chiral impurity in
S
-APR as well as quantification of the
S
-enantiomer.
Graphical Abstract
A novel, validated, reversed-phase (RP), chiral high performance liquid chromatography (HPLC) method was developed for the enantiopurity control analysis of naproxen, a frequently used non-steroidal ...anti-inflammatory agent using polysaccharide-type chiral stationary phase (CSP). In the screening phase of method development, seven columns were tested in polar organic (PO) mode using mobile phases consisting of 0.1% acetic acid in methanol, ethanol, 2-propanol, and acetonitrile. Enantiorecognition was observed only in five cases. The best enantioseparation was observed on a Lux Amylose-1 column with 0.1% (
/
) acetic acid in ethanol with a resolution (
) of 1.24. The enantiomer elution order was unfavorable, as the distomer eluted after the eutomer. When the ethanolic mobile phase was supplemented with water, enantiomer elution order reversal was observed, indicating a difference in the enantiorecognition mechanism upon switching from PO to RP mode. Furthermore, by changing ethanol to methanol, not only lower backpressure, but also higher resolution was obtained. Subsequent method optimization was performed using a face-centered central composite design (FCCD) to achieve higher chiral resolution in a shorter analysis time. Optimized parameters offering baseline separation were as follows: Lux Amylose-1 stationary phase, thermostated at 40 °C, and a mobile phase consisting of methanol:water:acetic acid 85:15:0.1 (
/
/
), delivered with 0.65 mL/min flow rate. Using these optimized parameters, a
= 3.21 ± 0.03 was achieved within seven minutes. The optimized method was validated according to the ICH guidelines and successfully applied for the analysis of different pharmaceutical preparations, such as film-coated tablets and gel, as well as fixed-dose combination tablets, containing both naproxen and esomeprazole.
Capillary zone electrophoresis employing a dual cyclodextrin (CD) system, consisting of anionic sulfobutylether-β-CD and native β-CD, was developed for the simultaneous chiral separation of four ...H1-antihistamine racemates (brompheniramine, chlorpheniramine, cetirizine and promethazine). A cost-effective screening using different native and derivatized, neutral and ionized CDs as chiral selectors was performed to find suitable derivatives for the dual CD system. Under the optimized conditions consisting of 25 mM phosphate background electrolyte at pH 7.0, a combination of 15 mM SBE-β-CD and 10 mM β-CD as chiral selectors, +25 kV applied voltage and 20 °C system temperature, the baseline chiral separation of all racemates was accomplished in less than 8 min. The method proved to be suitable for routine analysis, since it provided satisfactory results during sensitivity, linearity and repeatability studies.
