Analysis and pharmacokinetics of apomorphine in rat brain by microdialysis coupled with microbore HPLC electrochemical detection

The feasibility of an on-line microdialysis coupled with a sensitive microbore high performance liquid chromatography with electrochemical detection (HPLC-ED) system for the direct analysis of apomorphine was investigated. A microdialysis probe was inserted into the right striatum of male Sprague-Dawley rats, which had been administered apomorphine (10 mg/kg, i.v.). Brain dialysates were automatically injected into a cyano microbore column with an electrochemical detector through an on-line injector. Samples were eluted with a mobile phase containing 0.1 M monosodium dihydrogen phosphate-methanol (84:16, v/v, pH 3.0 adjusted with orthophosphoric acid) at a flow rate of 0.05 mL/min. A monophasic phenomenon with a elimination phase was observed from the brain apomorphine concentration-time curve. The results indicate that the brain pharmacokinetics of apomorphine appears to conform to a one-compartment model.