The validation criteria for analytical methods used in pharmacy practice research

Bioanalytical chromatographic method validation according to current regulations, with a special focus on the non-well defined parameters limit of quantification, robustness and matrix effect

Method validation is a mandatory step in bioanalysis, to evaluate the ability of developed methods in providing reliable results for their routine application. Even if some organisations have developed guidelines to define the different parameters to be included in method validation (FDA, EMA); there are still some ambiguous concepts in validation criteria and methodology that need to be clarified. The methodology to calculate fundamental parameters such as the limit of quantification has been defined in several ways without reaching a harmonised definition, which can lead to very different values depending on the applied criterion. Other parameters such as robustness or ruggedness are usually omitted and when defined there is not an established approach to evaluate them. Especially significant is the case of the matrix effect evaluation which is one of the most critical points to be studied in LC-MS methods but has been traditionally overlooked. Due to the increasing importance of bioanalysis this scenario is no longer acceptable and harmonised criteria involving all the concerned parties should be arisen. The objective of this review is thus to discuss and highlight several essential aspects of method validation, focused in bioanalysis. The overall validation process including common validation parameters (selectivity, linearity range, precision, accuracy, stability…) will be reviewed. Furthermore, the most controversial parameters (limit of quantification, robustness and matrix effect) will be carefully studied and the definitions and methodology proposed by the different regulatory bodies will be compared. This review aims to clarify the methodology to be followed in bioanalytical method validation, facilitating this time consuming step.

Practice research: Strategies for stability studies on hospital pharmaceutical preparations

This article describes the various tests that should be considered in the chemical stability testing of drugs prepared in hospital pharmacy. The requirement for a stability indicating analytical method to carry out such tests is emphasised.

A comparison of the modified score for the assessment of chronic rheumatoid affections of the hands and the australian/canadian osteoarthritis hand index in hand osteoarthritis patients

Objectives. To compare the modified score for the assessment and quantification of chronic rheumatoid affections of the hands (M-SACRAH) with the Australian/Canadian osteoarthritis hand index (AUSCAN) in hand osteoarthritis (HOA). Both are self-administered patient questionnaires, being designed to assess functional status, stiffness, and pain in affected patients, despite some differences in format, compass and arrangement of questions. Methods. 66 HOA patients (51 females), attending the outpatient clinic, were included. Patients completed the AUSCAN (15 visual analogue scales) (VAS) and the M-SACRAH (12 VAS). Results. AUSCAN-pain amounted to a mean of 41.9 (±2.9 SEM), AUSCAN-stiffness to 53.1 (3.7) and AUSCAN function to 42.6 (3.2). M-SACRAH-function amounted to 25.4 (2.4), M-SACRAH-stiffness to 42.6 (3.0), and M-SACRAH-pain to 43.7 (3.1). The total mean M-SACRAH was 37.2 (2.4) (all P's < .0001). The three respective domains of the two scores correlated significantly: pain: r = 0.73, stiffness: r = 0.75, and function: r = 0.76 (all P's < .0001). The four identical items in both scores also correlated significantly. No significant gender specific differences were observed. Conclusion. Despite a different scope of items, a significant high correlation of these two scores evaluating HOA patients could be demonstrated. We conclude that both scores are equivalently valuable for the assessment of health status in these patients.

Quantitative determination of amoxicillin in animal feed using liquid chromatography with tandem mass spectrometric detection

A liquid chromatographic tandem mass spectrometric (LC-MS/MS) method for the determination of amoxicillin (AMO) in animal feed was developed and validated. The method was used to examine the quality requirements for products intended for incorporation into animal feedingstuffs (medicated premixes), as documented in the EMEA/CVMP/080/95-Final guideline. After addition of the internal standard (ampicillin), the medicated feed samples were extracted using a 0.01 M potassium dihydrogenphosphate buffer solution (pH 4.5), followed by a centrifugation and filtration step. An appropriately diluted aliquot of the extract was analysed on a PLRP-S polymeric column (150 mm x 2.1 mm i.d., 100 A) using a mixture of 0.1% formic acid in water and acetonitrile as the mobile phase. Gradient elution was performed at a flow-rate of 0.2 mL min(-1). The mass spectrometer was used in the positive electrospray ionization MS/MS mode. The LC-MS/MS method was validated for linearity, trueness, precision, limit of quantification, limit of detection and specificity. The results fell within the ranges specified. The method was used for the homogeneity and stability testing of AMO in a commercial medicated feed. Some extracts were also injected onto a LC-UV and LC-fluorescence instrument (after pre-column derivatization with a formaldehyde reagent). These experiments showed that the LC-MS/MS method was superior with regard to speed of analysis, selectivity and sensitivity.

Assay validation for three antidepressants in pharmaceutical formulations: Practical approach using capillary gas chromatography

An easy and fast capillary gas chromatographic FID method, which was already described by the same authors for the simultaneous determination of fluoxetine, fluvoxamine and clomipramine without derivatization step, is now submitted to a validation procedure in several pharmaceutical formulations. Main aspects of the validation method are examined and discussed, since methods for regulatory submission in most cases must demonstrate: specificity in presence of all potential components, concentration range over which the response is lineal, accuracy, precision, acceptable detection and quantitation limits and stability of the procedure. The pharmaceutical preparations subject of validation were: 'Prozac' (capsules), 'Dumirox' (tablets) and 'Anafranil' (tablets) containing fluoxetine, fluvoxamine and clomipramine, respectively. The results presented in this report show the applied gas chromatographic method is acceptable for the determination of the three antidepressants in the pharmaceutical formulations above mentioned.

Voltammetric analysis of drugs

A review on the voltammetric analysis of drugs is presented. The review includes a summary of the rules that must be considered for drug analysis and a survey of the use of voltammetry for drug analysis in the period from 1998 till 2002.

3'-Azido-3'-deoxy-5'-O-isonicotinoylthymidine: a novel antiretroviral analog of zidovudine. II. Stability in aqueous media and experimental and theoretical ionization constants

Degradation of 3'-azido-3'-deoxy-5'-O-isonicotinoylthymidine (AZT-Iso), an antiretroviral derivative of zidovudine, was investigated in buffer pH 7.4, mu = 300 mOsm at 37, 50 and 60 degrees C, and in water (pH 6.6, 37 degrees C), giving zidovudine (AZT) and isonicotinic acid (INA) as products. The rate constants were determined by reversed-phase HPLC showing pseudo-first-order kinetics related to the residual amount of AZT-Iso. In this way, the studied compound was demonstrated to be 153 times more stable in water than in buffer solution at 37 degrees C. The analytical method was conveniently validated demonstrating to be a rapid and accurate stability-indicating technique. In addition, experimental and theoretical values of pKa were determined.

Validation of qualitative chromatographic methods: strategy in antidoping control laboratories

An experimental approach for the validation of chromatographic qualitative methods and its application in an antidoping control laboratory is described. The proposed strategy for validation of qualitative methods consists of the verification of selectivity/specificity, limit of detection (LOD), extraction recovery and repeatability (intra-assay precision). A one-day assay protocol, based on the analysis of five blank samples obtained from different sources and four replicates of control samples at two different concentrations of the analytes, has been defined to evaluate the validation parameters. The following evaluation criteria have been applied: absence of interfering substances at the retention time of the analytes in the blank samples to check the selectivity/specificity of the method, the LOD recommended by international sports authorities has to be attained, and for repeatability, the relative standard deviation should be <25% for the low concentration control sample and <15% for the high concentration control sample. Qualitative screening procedures are able to detect a great number of analytes so that extraction and analysis conditions are always a compromise for the different analytes. For this reason, no minimum acceptance criteria have been defined for data of extraction recoveries. The proposed protocol has been used for the validation of the screening and confirmation qualitative methods included in the scope of the accreditation of an antidoping control laboratory according to ISO quality standards.

Quantitative analysis of diclazuril in animal plasma by liquid chromatography/electrospray ionization mass spectrometry

A novel, sensitive and specific method for the quantitative determination of diclazuril in animal plasma using liquid chromatography combined with electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) with negative ion detection is presented. Extraction of the samples was performed with a rapid deproteinization step using acetonitrile. Chromatography of diclazuril and the internal standard was achieved on a Nucleosil ODS 5-microm column, using a gradient elution with 0.01 M ammonium acetate and acetonitrile. To obtain the highest sensitivity and specificity possible, the mass spectrometer was operated in the multiple reaction monitoring (MRM) mode. The method was validated according to the requirements defined by the European Community. Calibration curves using plasma fortified between 1-100 ng/mL and 100-2000 ng/mL showed good linear correlation (r >or= 0.9991, goodness-of-fit coefficient <or=7.0%). The trueness and within-run precision at 50 and 500 ng/mL did not exceed 8.8 and 10.5%, respectively. The between-run precision for the analysis of quality control samples at 50 and 1000 ng/mL was within 11.7%. The most striking advantage of the proposed method was the high sensitivity and specificity achieved. A limit of quantification of 1 ng/mL was obtained, for which the trueness and precision also fell within acceptable limits. Using a signal-to-noise ratio of 3:1, the limit of detection was calculated to be 0.03 ng/mL. The method has been successfully used for the quantitative determination of diclazuril in plasma samples from treated sheep, demonstrating the usefulness of the developed method for application in the field of pharmacology and pharmacokinetics.

Validation of a high-performance liquid chromatography assay for urinary nedocromil sodium following oral and inhaled administration

The validation of a solid-phase extraction and an ion pair high-performance liquid chromatographic assay for the determination of nedocromil sodium (NCS) in urine samples following oral and inhaled administration to healthy volunteers is described. NCS and its internal standard sodium cromoglycate (SCG) were extracted from urine samples using solid-phase extraction and then quantified using high-performance liquid chromatography (HPLC). A 25-cm C8 Spherisorb 5 microm stationary phase with a mobile phase containing a long alkyl chain ion-pair reagent (methanol-0.045 M phosphate buffer-0.05 M dodecyl triethyl ammonium phosphate; 550:447.6:2.4, v/v) was used. The mean (S.D.) intra-day accuracy and precision of the HPLC assay was 99.9 (1.6) and 7.05 (4.9)%, respectively. These values for the inter-day data were 102.4 (4.07) and 10.5 (2.7)%, respectively, over the concentration range investigated. The method described permits the detection of NCS in human urine at concentrations as low as 0.04 microg ml(-1) where the signal-to-noise ratio is greater than 3:1. In 10 healthy volunteers a significantly greater amount of NCS was excreted in the urine following inhalation than after oral dosing (p<0.001). The mean (S.D.) amount of NCS renally excreted at 0.5, 1.0 and 24 h following inhalation of four 2-mg doses of NCS from a metered dose inhaler (MDI) was 0.513 (0.24), 1.163 (0.49) and 4.00 (1.73)% of the nominal dose. Similar values after oral administration of 8 mg of NCS were 0.026 (0.03), 0.079 (0.06) and 0.930 (0.74)%, respectively.

Validation procedures of sedimentation field-flow fractionation techniques for biological applications

Sedimentation field-flow fractionation (SdFFF) offers great potential for the separation of submicrometer and micrometer-sized species. The availability of commercial instrumentation and the versatility of this method originated its success. At this stage of development, SdFFF techniques are mature enough for use in analytical research, development and even routine work. However, prior to their use, these techniques like any other methodologies, have to be validated. As the application of SdFFF techniques to cell separation is being constantly developed, we have investigated separation performance according to validation rules classically defined for separation methods (chromatography) in the case of cellular materials.