Determination of trimebutine and desmethyl-trimebutine in human plasma by HPLC

A simple and sensitive HPLC method has been developed to measure trimebutin e (CAS 39133-31-8, maleate: CAS 34140-59-5) and its main metabolite desmeth yl-trimebutine in human plasma. The method was validated according to the W ashington Consensus Conference on the Validation of Analytical Methods. It involved extraction of the plasma with n-hexane containing 2-pentanol, foll owed by reversed-phase HPLC using a Partisil(R) ODS2 10 mu m column and UV detection at 265 nm. The retention times of the interval standard (procaine ), desmethyl-trimebutine and trimebutine were 2.4, 4.3 and 6.5 min, respect ively The standard curves were linear from 20 ng . ml(-1) (limit of quantit ation) to 5000 ng . ml(-1) for both compounds. The coefficient of variation for all the criteria of validation were less than 15 %. The extraction rec overies obtained for trimebutine and desmethyl-trimebutine were about 90 %. Both compounds were very stable upon storage in plasma. The method was tes ted by measuring the plasma concentrations following oral administration to humans during a bioequivalence study and was shown suitable for pharmacoki netic studies.