Drug product analysis, sample preparation

For high reproducibility of migration times and peak areas the sample matrix should be identical for all samples analyzed together. While this is challenging for forensic applications where analytes in whole blood or urine are determined, this requirement can be fulfilled easily in pharmaceutical analysis. After sample preparation of the drug product, the sample matrix is similar in most cases. The composition of blood or urine depends on its source. Thus, the changing sample matrix has more impact on the quality of the CE analysis. 

Sample Preparation Perspectives in Drug Product Analysis... 

The recovery of a sample preparation must be assessed, because the recovery determines the accuracy of the analysis. For drug substance and drug product analysis, recovery of 100% is generally required to maintain required levels of accuracy and precision. For biological samples, less than quantitative recovery is generally acceptable if the recovery is reproducible. 

Next, reductive amination (step 4 in scheme 1) was exchanged with copper catalyzed palladium coupling (step 2 in scheme 1). Atomic absorption analysis for palladium in RWJ-26240 samples prepared by scheme 2 indicated that the level of palladium was reduced to an acceptable level. This improvement may be due to the two reduction steps subsequent to the use of palladium in scheme 2.177 The final major modification to the reaction scheme was the substitution of NaBH4 for NaBH3CN. The yield of product (60%) was determined by HPLC (Method 2). Reductive alkylation with formalin/NaBH4 afforded a pharmaceutically acceptable drug substance. 

Modern spectroscopy plays an important role in pharmaceutical analysis. Historically, spectroscopic techniques such as infrared (IR), nuclear magnetic resonance (NMR), and mass spectrometry (MS) were used primarily for characterization of drug substances and structure elucidation of synthetic impurities and degradation products. Because of the limitation in specificity (spectral and chemical interference) and sensitivity, spectroscopy alone has assumed a much less important role than chromatographic techniques in quantitative analytical applications. However, spectroscopy offers the significant advantages of simple sample preparation and expeditious operation. 

SAMPLE PREPARATION FOR HPLC ANALYSIS OF DRUG PRODUCTS... 

Table 12 gives an orientation help for CE separations sorted by pharmaceutical substances published in review articles. As this chapter focuses on the technical development of drug substances and products, only drug substances and drug formulations are covered. A useful compendium of CE applications in the pharmaceutical environment can be found in the book Capillary Electrophoresis Methods for Pharmaceutical Analysis written by G. Lunn. The book covers more than 700 active pharmaceutical ingredients and contains short method descriptions, sample preparation steps, and references. 

Accuracy. Sample solutions of known concentration (e.g., spiked placebo) are used for the accuracy determination. Experimental work may be organized so that the same stock solutions are used to prepare both linearity and accuracy solutions. The accuracy solution must be exposed to normal test conditions (e.g., mixing in a heated dissolution vessel). Determine any bias that is caused by the sampling and analysis of the solutions. If a dissolution profile of the drug product is required, accuracy determinations at different concentrations of the required profile will need to be performed (e.g., at 40, 75, and 110% of theoretical release). The results are reported as percent theory. 

Robustness of the sample analysis scheme Three samples will be prepared by spiking product B (known to contain < 0.05 ppm of element A) with element A to 0.5 ppm of element A in the drug product. 

Extraction can be used as an efficient and selective sample preparation method before analysis by chromatographic, spectroscopic, electroanalytical, or electrophoretic methods (see for example [5-10]). International norms from the International Standards Organization, US Food and Drug Administration, and US Environmental Protection Agency recommend application of extraction methods in analysis of food products and environmental and pharmaceutical samples. Novel ideas and new views concerning extraction have led to many controversies about terminology and to reallocation and softening of the boundaries between extraction and other analytical sample treatment techniques. 

The use of MRM methods for quantitative bioanalysis often reduces sample preparation and analysis time. The MRM method that used LC/ESI-MS/MS for the quantitative analysis of an anticancer drug, Yondelis (Ecteinascidin 743, ET-743, trabectedin. Scheme 9), in human plasma was demonstrated by Rosing et al. [103]. The full-scan mass spectrum of ET-743 (MW 762) contained an abundant [MH+ - H2O] ion at m/z 744 as a result of loss of water molecules from in-source CID (spectrum not shown). The internal standard, ET-729 (Scheme 9, MW 747), exhibited similar performance in the full-scan mass spectrum an abundant [MH+ - H2O] ion at tn/z 730 was produced. The product ion spectra of ET-743 and ET-729 exhibited the most abundant fragment ions at m/z 495 and m/z 479, respectively (spectra not shown). The product ion at m/z 495 (C27H31N2O7) was formed in the collision cell after cleavage of the sulfur bond and ester binding at C-11 [103]. 

The focus of automation is not solely on HPLC anymore (since it is automated), but also includes the sample preparation procedure for drug products since it involves many labor intensive steps (weighing, addition of sample solvent, extraction procedure, mixing, filtration, additional dilutions, second mixing, etc.). So, if the sample preparation procedures are automated and combined with HPLC, then the entire analysis is said to be fully automated whether it is for assay, CU, blend analysis, or even for dissolution testing. Such automated workstations are currently available from number of vendors (Caliper Life Science, SOTAX Inc.), but their ability to integrate with HPLC or UV spectrophotometer is left to the end users. This open-ended option depends on the end user requirements. 

The content of contaminants in foods is an altogether more demanding problem since contaminants are often present in trace quantities. Accordingly, it is necessary to resort to the sample preparation and trace enrichment techniques commonly used in environmental analysis. The types of problems that might be encountered include drug residues in meat products, furosine (known for its deteriorative and browning reaction) in... 

A Zymate II Pye system for automated analysis by the Zymark Corporation (USA) with on-line HPLC has been set up and used for content uniformity tests and assays, including process validation, for a variety of drug products in our QC laboratory since January 1992. The robotic system automatically performs the following operations preparation of sample and reference standard solutions, injection into HPLC, HPLC analyses, and generation of reports. 

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