Determination of dextromethorphan and dextrorphan in human urine by high performance liquid chromatography for pharmacogenetic investigations

The aim of the present study was to develop a sensitive method to measure dextromethorphan and dextrorphan in urine by HPLC to support pharmacogenetic studies in ethnic groups. Linearity was assessed in the range: 0.015-10 mug mL(-1) for dextromethorphan and 1-10 mug mL(-1) for dextrorphan. Inter and intra-day coefficients of variation were < 10%. Limits of detection and quantitation were 0.003 mug mL(-1) and 0.015 mug mL(-1) for dextromethorphan and 0.24 mug mL(-1) and 1.0 mug mL(-1) for dextrorphan, respectively. The method is reliable in helping determine the phenotype of Mexican ethnic groups using model drugs such as dextromethorphan.