Single-dose studies in animals are an important first step in establishing a safety profile. Note, however, that the calculation of an LD5o is no longer required or scientifically necessary. The aim of single-dose studies is to explore a range of doses. Identification of doses without drug-related effects, a dose that produces some level of exaggerated effect (not necessarily death) that helps identify potential side effects, and other doses in between helps all further toxicological (and clinical) tolerability assessments. These studies can be designed using 'up-and-down' or other tactics to reduce the time and number of animals required. These studies may then guide dose selection for the first repeated-dose studies. Various guidelines for the performance of these studies are available, and the ICH has also published its own guideline (Federal Register August 26 1996).
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