Design of Experiments for Capillary Electrophoretic Enantioresolution of Tamsulosin using Sulfated‐β‐Cyclodextrin as Chiral Selector

Quality by design-guided development of a capillary electrophoresis method for the simultaneous chiral purity determination and impurity profiling of tamsulosin

Analytical Quality by Design principles using the design of experiments were applied for the development of a capillary electrophoresis method for the determination of enantiomeric purity and chemically related impurities of tamsulosin. From initial scouting experiments, a dual cyclodextrin (CD) system composed of sulfated β-CD and carboxymethyl-α-CD was selected as the chiral selector. A fractional factorial resolution V+ design was used for the identification of the critical process parameters, while a face-centered central composite design and Monte Carlo simulations were employed for final optimization and defining the design space of the method. The experimental conditions of the working point were: 30 mM sodium phosphate buffer, pH 3.0, containing 40 mg/mL sulfated β-CD and 7 mg/mL carboxymethyl-α-CD, capillary temperature 18°C, applied voltage -23 kV. Following the assessment of robustness by applying a Plackett-Burman design, the method was validated according to the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use guideline Q2(R1). The method allowed the quantification of the chiral impurity and three other related impurities at the 0.1 % level with acceptable accuracy and precision.

Separation of tamsulosin enantiomers by capillary electrophoresis with tandem mass spectrometry and online stacking preconcentration

The aim of our work was to develop a new method for the analysis of tamsulosin enantiomers by capillary electrophoresis connected with tandem mass spectrometry. The pharmacologically active (R)-enantiomer of tamsulosin, is used to treat benign prostatic hyperplasia and chronic prostatitis. Under the optimal conditions, background electrolyte consisting of 200 mM acetic acid titrated with NH₄OH to pH 4.0 containing 4.0 mg mL^-1 sulfated β-cyclodextrin, an injection time of 40 s at 50 mbar, a voltage of 20 kV and an optimized MS set-up (as e.g., sheath liquid containing 75 : 24.9 : 0.1 MeOH, H₂O, and formic acid, v/v), a limit of detection of 1.6 nmol L^-1 was achieved. The method was validated in terms of linearity, detection and quantification limits, precision, recovery, and selectivity. The results showed that the method can be used for the analysis of tamsulosin enantiomers in environmental samples, but generally, it can be applied to many different analytical tasks.

Application of Experimental Design Methodologies in the Enantioseparation of Pharmaceuticals by Capillary Electrophoresis: A Review

Chirality is one of the major issues in pharmaceutical research and industry. Capillary electrophoresis (CE) is an interesting alternative to the more frequently used chromatographic techniques in the enantioseparation of pharmaceuticals, and is used for the determination of enantiomeric ratio, enantiomeric purity, and in pharmacokinetic studies. Traditionally, optimization of CE methods is performed using a univariate one factor at a time (OFAT) approach; however, this strategy does not allow for the evaluation of interactions between experimental factors, which may result in ineffective method development and optimization. In the last two decades, Design of Experiments (DoE) has been frequently employed to better understand the multidimensional effects and interactions of the input factors on the output responses of analytical CE methods. DoE can be divided into two types: screening and optimization designs. Furthermore, using Quality by Design (QbD) methodology to develop CE-based enantioselective techniques is becoming increasingly popular. The review presents the current use of DoE methodologies in CE-based enantioresolution method development and provides an overview of DoE applications in the optimization and validation of CE enantioselective procedures in the last 25 years. Moreover, a critical perspective on how different DoE strategies can aid in the optimization of enantioseparation procedures is presented.

Smart spectrophotometric assessment of tamsulosin hydrochloride and tadalafil in their new pharmaceutical formulation for treatment of benign prostatic hyperplasia and erectile dysfunction

A novel combination of tamsulosin hydrochloride and tadalafil is recently available for treatment of benign prostatic hyperplasia and erectile dysfunction. For the first time, four simple, accurate, smart and robust spectrophotometric methods have been suggested for their simultaneous quantification. The methods, namely; first derivative, ratio difference, derivative ratio and mean centering of ratio spectra, successfully resolved the spectral overlap of their challenging binary mixture. Calibration curves were linear at 2.0-40.0 and 2.0-55.0 μg/mL for tamsulosin hydrochloride and tadalafil, respectively. The methods were validated according to ICH guidelines and statistically compared with the official ones, revealing no considerable difference with respect to accuracy and precision. Specificity of the developed methods was assessed by evaluating various laboratory prepared mixtures. Furthermore, the methods were successfully applied for the quantification of the two drugs in their combined dosage form.

Multivariate optimization of capillary electrophoresis methods: a critical review

In this article a review on the recent applications of multivariate techniques for optimization of electromigration methods, is presented. Papers published in the period from August 2007 to February 2013, have been taken into consideration. Upon a brief description of each of the involved CE operative modes, the characteristics of the chemometric strategies (type of design, factors and responses) applied to face a number of analytical challenges, are presented. Finally, a critical discussion, giving some practical advices and pointing out the most common issues involved in multivariate set-up of CE methods, is provided.

The new HPLC methodology for the chiral separation of tamsulosin enantiomers on amylose tris(3,5-dimethylphenylcarbamate) stationary phase

New chromatographic method for the enantioseparation of (R,S)-tamsulosin and the determination of (R)- and (S)-tamsulosin was developed with the aid of amylose tris(3,5-dimethylphenylcarbamate) stationary phase. The method was compared to the known procedure for tamsulosin enantioseparation on cellulose tris(3,5-dimethylphenyl carbamate). Careful validation of both methods allowed to prove advantages of the new procedure: significantly better resolution as well as twice better sensitivity. The method was applied to quantification of (R)- and (S)-tamsulosin contents in prolonged release Apo-Tamis 0.4 mg hard capsules (Apotex Europe B.V) and Omnic Ocas 0.4 mg coated tablets (Astellas).

Box-Behnken design for the optimization of an enantioselective method for the simultaneous analysis of propranolol and 4-hydroxypropranolol by CE

An experimental design optimization (Box-Behnken design, BBD) was used to develop a CE method for the simultaneous resolution of propranolol (Prop) and 4-hydroxypropranolol enantiomers and acetaminophen (internal standard). The method was optimized using an uncoated fused silica capillary, carboxymethyl-beta-cyclodextrin (CM-beta-CD) as chiral selector and triethylamine/phosphoric acid buffer in alkaline conditions. A BBD for four factors was selected to observe the effects of buffer electrolyte concentration, pH, CM-beta-CD concentration and voltage on separation responses. Each factor was studied at three levels: high, central and low, and three center points were added. The buffer electrolyte concentration ranged from 25 to 75 mM, the pH ranged from 8 to 9, the CM-beta-CD concentration ranged from 3.5 to 4.5% w/v, and the applied run voltage ranged from 14 to 20 kV. The responses evaluated were resolution and migration time for the last peak. The obtained responses were processed by Minitab to evaluate the significance of the effects and to find the optimum analysis conditions. The best results were obtained using 4% w/v CM-beta-CD in 25 mM triethylamine/H3PO4 buffer at pH 9 as running electrolyte and 17 kV of voltage. Resolution values of 1.98 and 1.95 were obtained for Prop and 4-hydroxypropranolol enantiomers, respectively. The total analysis time was around of 15 min. The BBD showed to be an adequate design for the development of a CE method, resulting in a rapid and efficient optimization of the pH and concentration of the buffer, cyclodextrin concentration and applied voltage.

Optimization of capillary electrophoresis conditions for a glucagon competitive immunoassay using response surface methodology

The capillary electrophoresis (CE) conditions for a competitive immunoassay of glucagon were optimized for highest sensitivity of the immunoassay and resolution of the electrophoretic peaks using a Box-Behnken design. Injection time, voltage ramp time, and separation voltage were varied between three levels and two responses, bound-to-free (B/F) ratio of the immunoassay peaks and resolution between the peaks, were measured. Analysis of variance was applied to fit a predictive model, and a desirability function was used to simultaneously optimize both responses. A 10-s injection, 1.6-min ramp time, and a 22-kV separation voltage were the conditions found when high B/F was given more emphasis than high resolution. To test the model, calibration curves of a glucagon immunoassay were measured at the optimum and least optimum CE conditions. Optimal conditions increased the sensitivity of the immunoassay by 388% compared to the least optimum conditions while maintaining adequate resolution.

Design-of-experiment optimization of exhaled breath condensate analysis using a miniature differential mobility spectrometer (DMS)

Analytical instruments that can measure small amounts of chemicals in complicated biological samples are often useful as diagnostic tools. However, it can be challenging to optimize these sensors using actual clinical samples, given the heterogeneous background and composition of the test materials. Here we use gas chromatography-differential mobility spectrometry (GC/DMS) to analyze the chemical content of human exhaled breath condensate (EBC). Ultimately, this system can be used for non-invasive disease diagnostics. Many parameters can be adjusted within this instrument system, and we implemented a factorial design-of-experiments to systematically test several combinations of parameter settings while concurrently analyzing effects and interactions. We examined four parameters that affect sensitivity and detection for our instrument, requiring a 2(4) factorial design. We optimized sensor function using EBC samples spiked with acetone, a known clinical biomarker in breath. Two outputs were recorded for each experiment combination: number of chemicals detected, and the amplitude of acetone signal. Our goal is to find the best parameter combination that yields the highest acetone peak while also preserving the largest number of other chemical peaks in the spectra. By optimizing the system, we can conduct further clinical experiments with our sensor more efficiently and accurately.

Cyclodextrins in capillary electrophoresis enantioseparations--recent developments and applications

Capillary EKC has been established as a versatile and robust CE method for the separation of enantiomers. Within the chiral selectors added to the BGE CDs continue as the most widely used selectors due to their structural variety and commercial availability. This is reflected in the large number of practical applications of CDs to analytical enantioseparations that have been reported between January 2006 and January 2008, the period of time covered by this review. Most of these applications cover aspects of life sciences such as drug analysis, bioanalysis, environmental analysis, or food analysis. Moreover, new CD derivatives have been developed in an attempt to achieve altered enantioselectivities and to further broaden the application range. Finally, efforts will be summarized that aim at an understanding of the molecular level of the chiral recognition between CDs and the analytes.

Box-Behnken design: An alternative for the optimization of analytical methods

The present paper describes fundamentals, advantages and limitations of the Box-Behnken design (BBD) for the optimization of analytical methods. It establishes also a comparison between this design and composite central, three-level full factorial and Doehlert designs. A detailed study on factors and responses involved during the optimization of analytical systems is also presented. Functions developed for calculation of multiple responses are discussed, including the desirability function, which was proposed by Derringer and Suich in 1980. Concept and evaluation of robustness of analytical methods are also discussed. Finally, descriptions of applications of this technique for optimization of analytical methods are presented.