Measurement of naltrexone in rat brain regions and serum by high performance liquid chromatography with electrochemical detection

Summary A method is described for the determination of naltrex-one in discrete rat brain regions and serum. Separation and quantitation are performed by reversed-phase high-performance liquid chromatography with electrochemical detection. The drug gave a linear response over the range of 12.5–100ng for either 1.0ml for cerebellar homogenate or 25l for serum (1.25–10ng on column). Recoveries of naltrexone, added to the homogenate or serum, were 94±7 and 86±6%, respectively, when compared with naltrexone dissolved in water. The mean between-run relative standard deviations were 5.8 and 6.8% for cerebellar homogenate and serum, respectively, over the concentration range studied. The within-run relative standard deviations for cerebellar homogenate (12.5ng/ml) or serum (12.5ng/25l) were 7.7%. The application of the method to an in vivo animal experiment is demonstrated.