Abstract:

The deficiency of neuronal α7-nicotinic acetylcholine receptor (α7 nAChR) channel is implicated in cognition deficit and neuropsychiatric disorders. Chemical activation of α7 nAChR improves learning, memory, and sensory gating in animal models. To identify novel α7 nAChR activators, we recently identified a lead compound LD486 that as a positive allosteric modulator (PAM) selectively activates α7 nAChR. In this study we developed a simple, reliable and efficient assay of high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) and analyzed the pharmacokinetics of this novel LD486 in rat plasma. Separation of compound LD486 from plasma was achieved using a reversed-phase C₁₈ column with a mobile phase of 0.1% formic acid in H₂O (80:20, v:v), using compound A1223 as an internal standard (IS) with a flow rate of 0.5 mL/min. The quantitative analysis was performed using multiple reaction monitoring (MRM) at the specific ion transition of m/z 419.0 [M+H]⁺→m/z 169.0 for LD486 and m/z 400.0 [M+H]⁺→m/z 129.9 for A1223 in the positive ion mode with electrospray ionization (ESI) source. This validated LC-MS/MS method shows good linearity over the range 4–4000 ng/mL with the lowest limit of quantitation (LLOQ) at 4 ng/mL as well as satisfied intra- and inter-day precision, accuracy, extraction recovery and matrix effect.The stability testing indicates that LD486 in rat blood is stable under three freeze-thaw cycles, in room temperature at 22 ^oC for 2 h and 12 h, and for 2 weeks at −20 ^oC. This developed method was successfully applied to the pharmacokinetic analysis of intravenous (1 mg/kg) and oral (3 mg/kg and 30 mg/kg) administration of LD486 in SD rats.

Key words: AChR PAM, LD486, LC-MS/MS, Pharmacokinetics, Rat blood, α7