Pharmacokinetics and brain penetration of LF-3-88, (2-[5-[5-(2(S)-azetidinylmethoxyl)-3-pyridyl]-3-isoxazolyl]ethanol), a selective α4β2-nAChR partial agonist and promising antidepressant

LF-3-88 (2-[5-[5-(2(S)-azetidinylmethoxyl)-3-pyridyl]-3-isoxazolyl]ethanol) was identified as a highly selective α4β2-nAChRs partial agonist, with a K_i value of 0.4nM and EC₅₀ value of 110nM. A sensitive and selective ultra high pressure liquid chromatography-tandem mass spectrometry (UHPLC-MS-MS) method was developed and validated to study the pharmacokinetics profile of this compound in mice. Protein precipitation with acetonitrile was used to prepare the plasma and brain samples, and the recovery was greater than 90%. The inter-day and intra-day accuracy and precision of the quantitative method ranged from 95% to 106% for plasma and from 93% to 105% for brain homogenates. The precision of the assay was <10%. The limit of detection and limit of quantitation were 0.5ng/mL (1.8nM) and 1ng/mL (3.6nM), respectively. LF-3-88 was stable (>93%) for 24h on the bench top at room temperature, and for at least 3 weeks at 4°C and -80°C. The UHPLC-MS-MS assay was applied to the measurement of plasma and brain levels of LF-3-88 following oral administration to male Balb/c mice. Plasma concentrations of LF-3-88 and brain levels were dose-dependent with half-lives of approximately 60min and 180min, respectively, indicating good oral bioavailability and penetration of the blood-brain barrier.