A Sensitive Method for the Determination of Baclofen in Human CSF by High Performance Liquid Chromatography

Abstract Baclofen (4-amino-3p-chlorophenylbutyric acid) is used clinically for the treatment of multiple sclerosis and other spastic conditions. The intrathecal route of administration is now prefered to the oral route. To optimize efficacy, the levels of the drug in CSF need to be monitored after intrathecal administration. In this paper, the authors describe a sensitive reverse phase high performance liquid chromatographic method for the determination of baclofen in human CSF. This assay employed cation exchange extraction, pre-column derivatization with PITC, and ultra-violet detection (254 nm). The method was shown to be highly sensitive (5 to 10 ng/ml). This method was compared to a method using direct spectrophotometric detection of baclofen at 220 nm after direct application of CSF samples onto the chromatograph without prior extraction.