title: Simultaneous determination of nicotine and its metabolite, cotinine, in rat blood and brain tissue using microdialysis coupled with liquid chromatography: pharmacokinetic application.
abstract: To elucidate the disposition of nicotine in the brain is important because the neuropharmacological effects from nicotine exposure are centrally predominated. The aim of the present study was to develop a rapid and simple method for the simultaneous determination of unbound nicotine and its main metabolite, cotinine, in rat blood and brain tissue. We coupled a multiple sites microdialysis sampling technique with HPLC-UV system to characterize the pharmacokinetics of both nicotine and cotinine. Microdialysis probes were inserted into the jugular vein/right atrium and brain striatum of Sprague-Dawley rats, and nicotine (2 mg/kg, i.v.) was administered via the femoral vein. Dialysates were collected every 10 min and injected directly into a HPLC system. Both nicotine and cotinine were separated by a phenyl-hexyl column (150 mm x 4.6 mm) from dialysates within 12 min. The mobile phase consisted of an acetonitrile-methanol-20 mM monosodium phosphate buffer (55:45:900, v/v/v, pH adjusted to 5.1) with a flow-rate of 1 ml/min. The wavelength of the UV detector was set at 260 nm. The limit of quantification for nicotine and cotinine were 0.25 microg/ml and 0.05 microg/ml, respectively. Intra- and inter-day precision and accuracy of both measurements fell well within the predefined limits of acceptability. The blood and brain concentration-time profile of nicotine and cotinine suggests that nicotine is easily to get into the central nervous system and cotinine exhibits a long retention time and accumulates in blood.
authors.affiliation: Department of Pharmacy, Taipei Veterans General Hospital, Taipei, Taiwan.
authors.forename: Yuh-Lih
authors.initials: YL
authors.lastname: Chang
authors.forename: Pi-Lo
authors.initials: PL
authors.lastname: Tsai
authors.forename: Yueh-Ching
authors.initials: YC
authors.lastname: Chou
authors.forename: Jung-Hsiung
authors.initials: JH
authors.lastname: Tien
authors.forename: Tung-Hu
authors.initials: TH
authors.lastname: Tsai
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003367:Cotinine / Q000097:blood / Q000493:pharmacokinetics*; D017551:Microdialysis; D009538:Nicotine / Q000097:blood / Q000493:pharmacokinetics*; D051381:Rats; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013056:Spectrophotometry, Ultraviolet
chemical_list: D009538:Nicotine; D003367:Cotinine