When the patient was in a coma and has respiratory depression, the
plasma level of codeine was 114 ?g per liter, when the maximal expected
plasma level is in the range of 13 to 75 ?g per liter for the same dose in a
person with a normal CYP2D6 metabolism (Gasche, et al., 2004).  CYP2D6 genotyping showed three or more
functional alleles, which is consistent with ultra-rapid metabolism (Gasche, et al., 2004).