A new, simple, rapid, sensitive and economical spectrophotometric method has been developed and validated for estimation of lercanidipine in pure and its pharmaceutical formulation like tablet. During the development of formulations containing lercanidipine in its solid dosage form, analytical methods will serve as assay method for quantitation of the lercanidipine during product developmental stages. The present work consist of estimation of lercanidipine by difference spectrophotometry which is based on shifting of λ max by changing the pH of the solution by adding 0.1M HCl and 0.1M NaOH the absorption maximum was obtained. Linearity of the response was demonstrated for the drug for a range fulfilling Beer’s law, which is 5-25 μg/ml. The absorption maxima of lercanidipine were obtained at 260 nm in 0.1M NaOH, and 240 nm in 0.1M HCl. The results of analysis have been validated statistically and by recovery studies. The method was extended to pharmaceutical formulation and there were no interferences from any excipients and diluents. The full analytical validation was performed according to International Conference on Harmonization Q2R1 guidelines for validation of analytical procedures, supported by DryLab-models. 

Following administration of the acidic drug tolmetin (TOL) anaphylactic reactions occurred, which have been hypothesized to be related to the formation of reactive acyl glucuronides. Recently, glutathione adducts have been detected upon incubation of TOL with human liver microsomal preparations, which proved that oxidative activation might also be a pathway of formation of reactive—possibly toxic—glutathione metabolites of TOL. The aim of this work was to develop a new and robust HPLC method to investigate the in vivo effect of 2 coadministered drugs/nutritional supplements on the kinetics of TOL in rats (cimetidine, CIM) known to be a potent inhibitor of CYP3A4, an enzyme that catalyzes the oxidative metabolism and Quercetin, and QUE which induces UGT1A6, an enzyme involved in glucuronidation of acidic drugs. DryLab, a computer modeling software package, was used to assist in the development and optimization of the HPLC method used for separation of TOL and the two potential kinetic modulators together with three potential internal standards (zomepirac, carvedilol and fexofenadine). The method was validated in biological samples obtained from rats. 

Robust HPLC separations lead to fewer analysis failures and better method transfer as well as providing an assurance of quality. This work presents the systematic development of an optimal, robust, fast UHPLC method for the simultaneous assay of two APIs of an eye drop sample and their impurities, in accordance with Quality by Design principles. DryLab chromatography modeling software is employed to effectively generate design spaces (Method Operable Design Regions, MODR's), which are subsequently employed to determine the final method conditions and to evaluate robustness prior to validation.

In this study, some practical examples are presented that show the quality of separations using very efficient columns packed with the latest generation of core shell sub-3 μm and fully porous sub-2 μm particles in one-dimensional peptide separations supported by DryLab. This paper shows an approach for the analysis of proteins, such as high-resolution separations, and a data transformation process to improve peak recognition and analysis. Applying power functions on raw chromatographic data can be a neat tool in the field of biosimilar analysis, especially in comparability studies regarding the quality (primary structure) of proteins. Based on the results presented here, it can be stated that the use of power functions is beneficial for the comparison of chromatograms when peak areas are considered but has no effect when using peak heights. In this study, the new Acquity CSH columns (C18 and phenyl-hexyl) and the core–shell type wide pore Ascentis Express Peptide ES C18 material were applied with great success in peptide mapping. Finally, using phenyl-hexyl stationary phase in peptide separation seems to be a good alternative to the generally applied C18 or C4 phases.

The lipophilicity values of selected acridinone (imidazoacridinone and triazoloacridinone) derivatives were measured by gradient reversed-phase high-performance liquid chromatography (RP-HPLC) using a C18 stationary phase with a water/acetonitrile mixture as a mobile phase. The retention times obtained served as input data and appropriate log kw values (i.e., the retention factor log kw extrapolated to 0% organic modifier) as an alternative to log P were calculated using the DryLab program. The relationships between the lipophilicity (log kw) and the chemical structure of the studied compounds, as well as correlation between experimentally determined lipophilicities (log k_w) and log P data calculated using some commonly available software, are discussed.

In the present work it is shown that the linear elution strength (LES) model can be employed to predict retention times for segmented-temperature gradients based on temperature-gradient input data in liquid chromatography (LC) with high accuracy using DryLab-software. In order to predict retention times for temperature gradients with different start temperatures in LC, another relationship is required to describe the influence of temperature on retention. It could be shown that a plot of lnk vs. T yields more reliable isothermal/isocratic retention time predictions than a plot of lnk vs. 1/T which is usually employed. Retention times can be predicted with a maximal relative error of 5.5%(average relative error: 2.9%). As an example, the systematic method development for an isothermal as well as a temperature gradient separation of selected sulfonamides by means of the adapted LES model is demonstrated using a pure water mobile phase.