- The subject is classified as a CYP2D6 poor metabolizer (or an indeterminate metabolizer with neither allele known to be active) or CYP2D6 ultra-rapid metabolizer (or an indeterminate metabolizer where one allele is known to correspond to ultra-rapid metabolism) based on results of CYP2D6 genotyping performed at screening. (Note: Prior CYP2D6 genotyping results may be used for the purpose of determining study eligibility if a copy of the laboratory report is available and the genotyping results can be interpreted with the same classification system used by the study reference laboratory.)