Quantification of the metabolism rate of drugs such as psychotropic drugs, defined as the quotient of a drug's serum concentration (in nmol/L) by its prescribed daily dosage (in mg/day). This measure can also be standardised to allow comparison across multiple drugs by dividing individual CDR values by a reference CDR for the specific drug. The trait is concentration dose ratio (EFO_0007635). Also known as: CDR measurement.