This paper describes a multifactorial optimization of four critical HPLC method parameters, i.e. gradient time (tG), temperature (T), pH and ternary composition (B1:B2) based on 36 experiments. The effect of these experimental variables on critical resolution and selectivity was carried out in such a way as to systematically vary all four factors simultaneously. The basic element is a gradient-time temperature (tG-T) plane, which is repeated at three different pHs of the eluent A and at three different ternary compositions of eluent B between methanol and acetonitrile. The so-defined volume enables the investigation of the critical resolution for a part of the Design Space of a given sample. Further improvement of the analysis time, with conservation of the previously optimized selectivity, was possible by reducing the gradient time and increasing the flow rate. Multidimensional robust regions were successfully defined and graphically depicted.

Quality-by-design (QbD) is a systematic approach to drug development, which begins with predefined objectives, and uses science and risk management approaches to gain product and process understanding and ultimately process control. The concept of QbD can be extended to analytical methods. QbD mandates the definition of a goal for the method, and emphasizes thorough evaluation and scouting of alternative methods in a systematic way to obtain optimal method performance. Candidate methods are then carefully assessed in astructured manner for risks, and are challenged to determine if robustness and ruggedness criteria are satisfied. As a result of these studies, the method performance can be understood and improved if necessary, and a control strategy can be defined to manage risk and ensure the method performs as desired when validated and deployed. In this review, the current state of analytical QbD in the industry is detailed with examples of the application of analytical QbD principles to a range of analytical methods, including high-performance liquid chromatography, Karl Fischer titration for moisture content, vibrational spectroscopy for chemical identification, quantitative colormeasurement, and trace analysis for genotoxic impurities.

An ultra performance liquid chromatographic (UPLC) method was developed for simultaneous determination of seven steroid (dienogest, finasteride, gestodene, levonorgestrel, estradiol, ethinylestradiol, and norethisterone acetate) active pharmaceutical ingredient (API) residues. Two gradients—two column temperature basic model runs were carried out and DryLab was used to predict the optimal solvent ratio, which would give sufficient resolution (Rs > 1.5) between the compounds and peaks originated from sampling matrix. The new, generic method is presented, with which it is possible to verify the cleaning process of a steroid producing equipment line used for the production of various pharmaceuticals. The UPLC method was validated using an UPLC™ BEH C18 column with a particle size of 1.7m (50mm×2.1mm) and acetonitrile–water (48:52, v/v) as mobile phase at a flow rate of 0.55 ml/min. Method development and method validation for cleaning control analysis are described. The rapid UPLCmethod is suitable for cleaning control assays within good manufacturing practices (GMP) of the pharmaceutical industry.

In the present study a computer simulation software DryLab and a chemometric (response surface) approach were used in developing and optimizing a reverse-phase HPLC separation of moxifloxacin and its related impurities and degradation products of moxifloxacin. The separation of four synthesis-related impurities was achieved on a Waters C18 XTerra column using a mobile phase of (water + triethylamine (2%, v/v)): acetonitrile = 90:10 (v/v%), the pH of water phase being adjusted with phosphoric acid to 6.0. The column was thermostated at 45 °C. The resolution between the two least resolved impurity peaks was in average, R_s,min > 1.5. Method validation parameters indicate linear dynamic range 0.2–2.0 μg/ml with LOQ ca. 0.20 μg/ml and LOD ca. 0.05 μg/ml for all analytes. The method was applied for the impurities determination in drug tablets and infusion (Avelox®, Bayer AG) and for degradation products determination in a stability study of moxifloxacin. The impurity content in the tablets and infusion was quantified as 0.1% of total drug. 

A comprehensive automated strategy for the development of a RPLC-UV-method for a basic drug candidate (pKa 7.7), its impurities, and degradants was demonstrated by using multidimensional screening and analysis (MeDuSA) and DryLab computer optimization software. DryLab software was used to model the effect of temperature, pH, and ionic strength of the buffer on resolution and peak shape to determine the design space of the method and establish the optimal operating conditions. In silico optimization supported by DryLab enabled the determination of the optimum conditions without carrying out trial-and-error simulations. Excellent agreement between DryLab simulation and experimental results was obtained. As a result, decreased run time (from 35 to 14 min compared to the original method) was developed.

The paper describes a strategy for the systematic development of ultra high pressure liquid chromatographic (UHPLC or UPLC) methods using 5 cm × 2.1mm columns packed with sub-2µm particles and computer simulation with the DryLab® package. Data for the accuracy of computer modeling in the Design Space under UPLC conditions are reported. An acceptable accuracy for these predictions of the computer models is presented. The work illustrates a method development strategy, focusing on time reduction up to a factor 3–5, compared to the conventional HPLC method development and exhibits parts of the Design Space elaboration as requested by the FDA and ICH Q8R1. Furthermore this paper demonstrates the accuracy of retention time prediction at elevated pressure (enhanced flow-rate) and shows that the computer-assisted simulation can be applied with sufficient precision for UHPLC applications (p > 400 bar). Examples of fast and effective method development in pharmaceutical analysis, both for gradient and isocratic separations are presented.