A ruggedness test strategy for procedure related factors: experimental set-up and interpretation

The determination of two analogues of 4-(azidomethyl)-1,1'-biphenyl as potential genotoxic impurities in the active pharmaceutical ingredient of several sartans containing a tetrazole group

4'-(azidomethyl)-[1,1'-biphenyl]-2-carbonitrile (GTI-azide-1) and 5-(4'-(azidomethyl)-[1,1'-biphenyl]-2-yl)-1H-tetrazole (GTI-azide-2) are potentially genotoxic impurities that can be present at trace levels in the active pharmaceutical ingredients and drug products of sartans containing a tetrazole group. A method of high-performance liquid chromatography coupled with mass spectrometry, that allows the determination of those genotoxic impurities at sub-ppm level relative to the active pharmaceutical ingredient, was developed. The method utilises a very efficient liquid chromatograph Waters Acquity I-Class coupled with a highly sensitive tandem mass spectrometer Xevo TQ-XS. The separation was achieved on a column Acquity UPLC BEH Shield RP18 1.7 μm employing a linear elution gradient. The mass spectrometer was used with a heated electrospray ionization. The method was found to be sufficient in terms of sensitivity, linearity, precision, accuracy, selectivity and robustness and is easily applicable in the pharmaceutical quality control environment. The method allows for accurate quantification of both impurities GTI-azide-1 and GTI-azide-2 at levels below 1/10^th of the specification limit, which is crucial in the context of pharmaceutical analysis. The limit of quantification was determined to be 0.033 ppm and 0.025 ppm for GTI-azide-1 and GTI-azide-2, respectively.

Development and Validation of an Affinity Chromatography-Protein G Method for IgG Quantification

Nimotuzumab, an IgG that recognizes the epidermal growth factor receptor (EGF-R) overexpressed in some tumors, is used in the treatment of advanced head and neck cancer. For the quantification of this protein in cell culture supernatants, protein G-HPLC affinity chromatography is used due to its high affinity and specificity for antibodies of this class. The technique relies on the comparison of the area under the curve of the elution peak of the samples to be evaluated versus to a calibration curve of well-known concentrations and was validated by assessment of its robustness, specificity, repeatability, intermediate precision, accuracy, linearity, limit of detection, limit of quantification, and range. According to results of the study all validation parameters fulfilled the preestablished acceptance criteria and demonstrated the feasibility of the assay for the analysis of samples of cell culture supernatant as well as drug product.

Harmonization of strategies for the validation of quantitative analytical procedures. A SFSTP proposal--part II

As reported in a previous paper, the main objective of the new commission of the Société Française des Sciences et Techniques Pharmaceutiques (SFSTP) was the harmonisation of approaches for the validation of quantitative analytical procedures. In a series of meetings, members of this Commission have first tried to review the objectives of analytical methods and the objectives of validation methods and to recommend the use of two-sided beta-expectation tolerance intervals for total error of validation samples (accuracy profile) in the acceptance/rejection of analytical method in validation phase. In the context of the harmonization, the other objectives were: (i) to propose a consensus on the norms usually recognized, while widely incorporating the ISO terminology; (ii) to recommend to validate the analytical procedure accordingly to the way it will be used in routine; (iii) to elaborate a rational, practical and statistically reliable strategy to assure the quality of the analytical results generated. This strategy has been formalised in a guide and the three latter objectives made by the Commission are summarised in the present paper which is the second part of summary report of the SFSTP commission. The SFSTP guide has been produced to help analysts to validate their analytical methods. It is the result of a consensus between professionals having expertise in analytical and/or statistical fields. The suggestions presented in this paper should therefore help the analyst to design and perform the minimum number validation experiments needed to obtain all the required information to establish and demonstrate the reliability of its analytical procedure.

Ruggedness and robustness testing

Due to the strict regulatory requirements, especially in pharmaceutical analysis, analysis results with an acceptable quality should be reported. Thus, a proper validation of the measurement method is required. In this context, ruggedness and robustness testing becomes increasingly more important. In this review, the definitions of ruggedness and robustness are given, followed by a short explanation of the different approaches applied to examine the ruggedness or the robustness of an analytical method. Then, case studies, describing ruggedness or robustness tests of high-performance liquid chromatographic (HPLC), capillary electrophoretic (CE), gas chromatographic (GC), supercritical fluid chromatographic (SFC), and ultra-performance liquid chromatographic (UPLC) assay methods, are critically reviewed and discussed. Mainly publications of the last 10 years are considered.

Spectrophotometric method for polyphenols analysis: prevalidation and application on Plantago L. species

The prevalidation strategy was applied to evaluate UV-vis spectrophotometric procedure with Folin-Ciocalteu's reagent for polyphenols determination. Favourable prevalidation characteristics verified this procedure as a valuable tool in polyphenols analysis and it was successfully applied for determination of total polyphenols and tannins in leaves, stems and flowers of Plantago L. species growing in Croatia. The results showed the variety of total polyphenols content between different plant parts (leaves: up to 10.15%; stems: up to 4.34% and flowers: up to 5.56%). The content of tannins in stems was from 0.28% to 1.00%, while leaves and flowers contained tannins in concentrations of 2.26% and 2.21%, respectively. The results of polyphenols determination were evaluated by using multivariate analysis (UPGMA and PCA) as a contribution to elucidation of relations between different taxa of genus Plantago L.

Harmonization of strategies for the validation of quantitative analytical procedures. A SFSTP proposal--Part I

This paper is the first part of a summary report of a new commission of the Société Française des Sciences et Techniques Pharmaceutiques (SFSTP). The main objective of this commission was the harmonization of approaches for the validation of quantitative analytical procedures. Indeed, the principle of the validation of theses procedures is today widely spread in all the domains of activities where measurements are made. Nevertheless, this simple question of acceptability or not of an analytical procedure for a given application, remains incompletely determined in several cases despite the various regulations relating to the good practices (GLP, GMP, ...) and other documents of normative character (ISO, ICH, FDA, ...). There are many official documents describing the criteria of validation to be tested, but they do not propose any experimental protocol and limit themselves most often to the general concepts. For those reasons, two previous SFSTP commissions elaborated validation guides to concretely help the industrial scientists in charge of drug development to apply those regulatory recommendations. If these two first guides widely contributed to the use and progress of analytical validations, they present, nevertheless, weaknesses regarding the conclusions of the performed statistical tests and the decisions to be made with respect to the acceptance limits defined by the use of an analytical procedure. The present paper proposes to review even the bases of the analytical validation for developing harmonized approach, by distinguishing notably the diagnosis rules and the decision rules. This latter rule is based on the use of the accuracy profile, uses the notion of total error and allows to simplify the approach of the validation of an analytical procedure while checking the associated risk to its usage. Thanks to this novel validation approach, it is possible to unambiguously demonstrate the fitness for purpose of a new method as stated in all regulatory documents.

Prevalidation in pharmaceutical analysis

A complete prevalidation, as a basic prevalidation strategy for quality control and standardization of analytical procedure was inaugurated. Fast and simple, the prevalidation methodology based on mathematical/statistical evaluation of a reduced number of experiments (N < or = 24) was elaborated and guidelines as well as algorithms were given in detail. This strategy has been produced for the pharmaceutical applications and dedicated to the preliminary evaluation of analytical methods where linear calibration model, which is very often occurred in practice, could be the most appropriate to fit experimental data. The requirements presented in this paper should therefore help the analyst to design and perform the minimum number of prevalidation experiments needed to obtain all the required information to evaluate and demonstrate the reliability of its analytical procedure. In complete prevalidation process, characterization of analytical groups, checking of two limiting groups, testing of data homogeneity, establishment of analytical functions, recognition of outliers, evaluation of limiting values and extraction of prevalidation parameters were included. Moreover, system of diagnosis for particular prevalidation step was suggested. As an illustrative example for demonstration of feasibility of prevalidation methodology, among great number of analytical procedures, Vis-spectrophotometric procedure for determination of tannins with Folin-Ciocalteu's phenol reagent was selected. Favourable metrological characteristics of this analytical procedure, as prevalidation figures of merit, recognized the metrological procedure as a valuable concept in preliminary evaluation of quality of analytical procedures.

Validation of an HPLC method on short columns to assay ketoconazole and formaldehyde in shampoo

An HPLC method to determine simultaneously ketoconazole and formaldehyde in an anti-dandruff shampoo, originally developed on a long column, was transferred to two short columns with similar stationary phase properties, but with a length of at the most 30% of the initial one. Using the conventional column as reference, the fast HPLC methods on the short columns were validated. The validation characteristics consisted of selectivity, linearity range, precision (repeatability and time-different intermediate precision), bias and robustness. For the ketoconazole assay, linearity for peak area was found in the concentration range up to 0.20 mg/ml. For formaldehyde, two calibration ranges (0-10 x 10(-5) and 0-10 x 10(-4)%) were linear, both for peak area and height. The assays for both ketoconazole and formaldehyde in these ranges showed no bias and an acceptable precision, although the precision found with the short columns was slightly worse than with the long one. The robustness tests were performed applying a Plackett-Burman design. For the ketoconazole assay, 6 factors were examined in a 12 experiments design and for formaldehyde, 11 factors in 16 experiments. The methods were found to be robust. Despite the somewhat less good precision the transfer seems to be successful and the obtained assays on the short columns are applicable for fast routine analysis.

Derivation of system suitability test limits from a robustness test on an LC assay with complex antibiotic samples

A System Suitability Test (SST) is a test to verify the adequate working of the equipment used for analytical measurements. In pharmaceutical analysis, SSTs are performed at least at the beginning of a series of routine analyses. The most generally applied SST considers the precision of the analysis, i.e. the repeatability standard deviation must not exceed a predefined value. Additionally, a SST can also consider responses indicative for the quality of the technique used, e.g. resolutions between peaks or peak asymmetry in high performance liquid chromatography. The system is then only declared suitable if the response is within given limits. However, it is not always evident how to define the SST limits to be fulfilled for a newly developed method. Robustness tests have been proposed as a starting point in a strategy to deduce these limits. Here, it is examined how such a strategy can be applied for complex samples of microbial origin.

Simultaneous determination of ketoconazole and formaldehyde in a shampoo: liquid chromatography method development and validation

Ketoconazole is an antifungal agent, which is the active ingredient in a shampoo primarily used for the treatment of seborrhatic dermatitis (anti-dandruff shampoo). The shampoo also contains imidazolidinylurea as a formaldehyde releasing preservative. The aim of this study was to develop a HPLC system that allows the determination of both ketoconazole and formaldehyde. The finally selected isocratic system consisted of an Interchrom Nucleosil (250 X 4.6 mm, 5 microm) C8 column and a mobile phase containing acetonitrile-phosphate buffer 0.025 M, pH 4.0, 45/55 (v/v). Ketoconazole could immediately be determined at 250 nm after injection of diluted shampoo. Formaldehyde was measured at 345 nm after derivatisation with a 2,4-dinitrophenylhydrazine solution. At the selected conditions, the other excipients of the shampoo did not interfere in the assays for both substances. Method validation was performed on both assays. Different selectivity towards ketoconazole and formaldehyde was observed when applying other C8 columns. This fact, however, did not affect the assays of both substances.

Guidance for robustness/ruggedness tests in method validation

This paper is intended to give guidance in setting-up and interpreting a robustness test. The different steps in a robustness test are discussed and illustrated with examples. The recommendations given for the different steps are based on approaches found in the literature, several case studies performed by the authors and discussions of the authors within a commission of the French SFSTP (Société Française des Sciences et Techniques Pharmaceutiques). In the end of the paper a worked-out example is given of a robustness test case study set up and interpreted according to the guidelines.

Supersaturated designs for robustness testing

Supersaturated designs are factorial designs in which the number of factors examined exceeds the number of experiments performed. They do not allow an estimation of individual effects, since even the main effects are confounded. However, the total variance of a response estimated from such a design can in principle be used as a measure for the robustness of the method. A number of case studies were examined to determine whether the variance estimated from a supersaturated design is similar to the one from a Plackett-Burman design. This was found to be the case, which means that the estimated variance describes well the variation in the response caused by the variation in the factors.

Robustness testing of a reversed-phase high-performance liquid chromatographic assay: comparison of fractional and asymmetrical factorial designs

Robustness tests were performed on a reversed-phase HPLC assay for triadimenol. Different experimental designs were compared. Two-level fractional factorial designs with different resolutions were used to study the influence of procedure-related factors. The factors chromatographic column manufacturer at four levels and instrument at three levels were stepwise included in the study using asymmetrical factorial designs. The significance of the factor effects was determined statistically, using two types of error estimates in the calculation of critical effects, and graphically, by means of half-normal plots. The asymmetrical designs turned out to be an efficient and economic method to examine the influence of factors at different numbers of levels in the robustness testing of analytical methods.

Nested designs in ruggedness testing

Nested designs were performed in order to execute a ruggedness test according to the United States Pharmacopeia definition for ruggedness, in which mainly non-procedure related factors are examined. Several nested designs have been executed on a high performance liquid chromatography assay to determine tetracycline and related substances in bulk samples of tetracycline. Factors such as different laboratories, analysts, instruments, columns, days and batches were examined. The interpretation methods described in the literature were found to cause problems. In these methods the variances of the examined factors are estimated from the calculated mean square values and from the equation for the expected mean squares. Very frequently, negative variance estimates were obtained. Their absolute values were found to be dependent on the influence of the factor examined below it in the design, on the examined response. Therefore an alternative interpretation method for nested designs, based on pooled variances, was proposed and found to be appropriate to use for ruggedness testing purposes. Both approaches, the one from the literature and the one proposed here, were tested on simulated data coming from a nested design with four factors and on the experimentally measured data.

RTS, a computer program for the experimental set-up and interpretation of ruggedness tests

A computer program is described for the experimental set-up and interpretation of ruggedness tests. The implemented strategy was based on a number of case studies and contains both recommended designs and minimal designs. The minimal designs reduce the number of experiments, but they cannot be statistically interpreted based on the interaction or dummy factor effects. The use of randomization tests as an alternative statistical interpretation method for the significance of the effects was examined. Some of the minimal designs are expandable to designs with characteristics similar to those of the recommended designs. The program is designed to facilitate the selection of the designs and the interpretation of the results and to prevent or detect problems such as drifting of responses.

Ruggedness testing of chromatographic methods: selection of factors and levels

The first step in a ruggedness test is the selection of factors to be examined and their levels. In this paper, both topics are discussed, thereby completing a strategy described earlier. It is demonstrated, by means of some examples, that depending on the formulation (definition) of a factor, information that is physically more or less meaningful is extracted from the experimental design results. Among others, the inclusion of the compounds of a buffer and of the components of a mixture in a screening design were examined. A general guideline to select the levels of the factors in a ruggedness test was proposed. Some special cases, i.e. asymmetric intervals around the nominal level, were also discussed.