Generic HPLC

For discovery PK samples, rapid method development is required. For HPLC/MS/MS assays, method development can be achieved within 2 hr if no unusual problems are encountered. Xu et al.101 described a process for rapid method development as part of the discovery PK paradigm. As shown in Figure 7.4, the systematic process is based on using protein precipitation as the sample clean-up step and generic HPLC conditions for the HPLC/MS/MS assay. 

For a liquid or semi-solid pharmaceutical dosage form, it is crucial to include a preservative in the formulation. Commonly used preservatives in these systems include sodium benzoate, EDTA, sorbic acid, and parabens. A generic HPLC method is also recommended for the preservatives used in liquid formulations for routine monitoring to ensure the stability of the preservative itself and it must be validated specific to its use with the dosage form. (See chapters on Sample Preparation and Method Development.)... 

To avoid bottlenecks in the analysis, each step should be automated. Automation of data acquisition is achieved by automated HPLC/UV/MS/ ELSD instruments, equipped with autosamplers that allow compounds to be batch analyzed in unattended fashion. Recently, fast generic HPLC methods have been implemented for analysis of combinatorial libraries [33 53]. 

The fifth major improvement was to use a fast generic gradient method for the analysis of the samples, which usually takes place in an overnight run of. sample vials from 24 compounds. The fast generic HPLC methods have been discussed in Chapter 2. The method applied here was a 3.5 min gradient from 0 to 95% acetonitrile using a Supelcosil-ABZ 30 x 4.6 mm column with a 1.5 ml/min flow rate. Together with the re-equilibration time the cycle time for each sample was 7.5 min. 

Mutton, LM. Fast Generic HPLC Methods, pp.73-85 in Valko, K., ed.. Separation Methods in Drug Synthesis and Purification, Elsevier Science, Amsterdam, (2000). 

A preservative is a substance that extends the shelf-life of drug products by preventing oxidation or inhibiting microbial growth.14 Preservatives must be monitored in the products since they are considered to be active components. Generic HPLC assays are typically developed for preservatives such as buty-lated hydroxytoluene (BHT), an antioxidant for solid dosage forms, and antimicrobials such as parabens, sodium benzoate, or sorbic acid in liquid formulations. For these additive components, typical assay specifications are 85-115% of label claim. 

TABLE 8.6 Experimental Factors before and after Optimization of the Generic HPLC-MS/MS Method... 

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