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 m icrobore high performance liquid chromatography with electrochemical d etection (HPLC-ED) system for the direct analysis of apomorphine was i nvestigated. A microdialysis probe was inserted into the right striatu m 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 adjust ed with orthophosphoric acid) at a flow rate of 0.05 mL/min. A monopha sic phenomenon with a elimination phase was observed from the brain ap omorphine concentration-time curve. The results indicate that the brai n pharmacokinetics of apomorphine appears to conform to a one-compartm ent model.