A method of reducing a risk of misuse of a drug in a subject comprising: determining a daily dose of a drug prescribed in the subject, wherein the drug comprises oxycodone, controlled release oxycodone or an oxycodone metabolite； measure a concentration of the drug in the subject's urine； measure the parameters associated with the subject consisting of the specific gravity of the urine, the pH of the urine and the lean body mass of the subject； calculate a normalized value (N) as a function of (i) drug concentration and (ii) the parameters that use the following equation: [N]>； = [C] x ((GEN-1.00) / (GE -1.00) x (PCM / 122) x (pH / 8.50) 0.56, where [C] is the crude drug concentration in ng / ml, GEN is the specific gravity of normalized urine, GE is The specific gravity of the urine, PCM is the lean body weight of the subject and pH is the pH of the urine； compare the normalized value with an estimate of the mean or the normalized median corresponding to the daily dose of the prescribed drug； identify the subject with a high risk of drug misuse if the normalized drug concentration is outside the estimate of the average or the normalized median corresponding to the prescribed daily dose of the drug； and, subsequently, alter the daily dose of the drug prescribed to the subject.Un método para reducir un riesgo de mal uso de un fármaco en un sujeto que comprende: determinar una dosis diaria de un fármaco prescrita en el sujeto, donde el fármaco comprende oxicodona, oxicodona de liberación controlada o un metabolito de oxicodona； medir una concentración del fármaco en la orina del sujeto； medir los parámetros asociados con el sujeto que consisten en la gravedad específica de la orina, el pH de la orina y la masa corporal magra del sujeto； calcular un valor normalizado (N) como una función de (i) la concentración de fármaco y (ii) los parámetros que usan la siguiente ecuación: [N] >；= [C] x ((GEN-1,00)/(GE-1,00) x (PCM/122) x (pH/8,50)0,56, donde [C] es la concentrac
