Typical bioanalytical method changes that fall into this category include, but are not limited to, bioanalytical method transfers between laboratories no or analysts, instrument and/or software platform changes, change in species within matrix (e.g., rat plasma to mouse plasma), changes in matrix within a species (e.g., human plasma to human urine), change in analytical methodology (e.g., change in detection systems), and change in sample processing procedures. Cross-validation Cross-validation is a comparison of two bioanalytical methods. Cross-validations are necessary when two or more bioanalytical methods are used to generate data within the same study. For example, an original validated bioanalytical method serves as the ��reference�� and the revised bioanalytical method is the ��comparator.

�� The comparisons should be done both ways. Cross-validation with spiked matrix and subject samples should be conducted at each site or laboratory to establish interlaboratory reliability when sample analyses within a single study are conducted at more than one site, or more than one laboratory, and should be considered when data generated using different analytical techniques [e.g., LC-MS (Liquid chromatography mass spectroscopy) vs. enzyme-linked immunosorbent assay (ELISA)] in different studies are included in a regulatory submission. VALIDATION PARAMETERS Linearity Linearity assesses the ability of the method to obtain test results that are directly proportional to the concentration of the analyte in the sample. The linear range of the method must be determined regardless of the phase of drug development.

Table 1 indicates US Food and Drug Administration (FDA) guidelines for bioanalytical method validation. ICH guidelines recommend evaluating a minimum of five concentrations to assess linearity. The five concentration levels should bracket the upper and lower concentration levels evaluated during the accuracy study.[4] ICH guidelines recommend the following concentration ranges be evaluated during method validation: Table 1 US FDA guidelines for bioanalytical method validation Assay (finished product or drug substance): 80�C120% of the sample concentration. This range must bracket that of the accuracy study, however. If accuracy samples are to be prepared at 80, 100, and 120% of nominal, then the linearity range should be expanded to a minimum of 75�C125%.

Content uniformity method: 70�C130% of the sample concentration, unless a wider, more appropriate, range is justified based on the nature of the dosage form (e.g., metered dose inhalers). Dissolution method: This requires ��20% of the specified range. AV-951 In cases where dissolution profiles are required, the range for the linearity evaluation should start below the typical amount recovered at the initial pull point to 120% of total drug content.