Article/carrier mixtures homogeneity tests

The requirements of 58.113(a) substantially changed the state of the art for the conduct of nonchnical laboratory studies. Prior to the promulgation of GLP regulations, anal5di-cal tests to estabhsh the homogeneity and stabihty of article/ carrier mixtures were not routine, nor were tests to determine the concentration of test and control articles in the mixtures used to dehver test and control articles to test systems. 

StabUity of the article/carrier mixture can be established in conjimction with the homogeneity assays of nonsolutions. Separate stabdity tests will, of course, be required for solutions. Formal stability trials sufficient to show long-term sta-bdity of the mixtures are not required rather, stabdity shoidd be estabhshed for a period that encompasses the period of use of the article/carrier mixture. Period of use shoidd be defined as whichever of the foUowing two time periods is longer, the time between preparation of the mixture and final administration of that mixture to the test system, or the time between preparation of the mixture and the analysis of the mixture as required by 58.113(a)(2). Often the period between preparation and analysis may be longer than the period between preparation and last administration to the test system. 

Tests to estabhsh the stabihty and homogeneity of article/carrier mixtures as well as the periodic concentration analyses of the mixtures must be conducted in full comph-ance with the GLP regulations. 

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