LC‐MS/MS Method for Quantifying the Alterations of Four Neurotransmitters in Plasma From Insomnia Patients Treated With Zhibai Anshen Oral Liquid

Zhibai Anshen (ZbAs) oral liquid is employed to alleviate insomnia. However, the neurotransmitters in this treatment are insufficiently investigated. This study aimed to establish a method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for determination of 5-hydroxytryptamine (5-HT), dopamine (DA), epinephrine (E), and norepinephrine (NE) in the plasma of patients treated with ZbAs. Plasma samples were processed by protein precipitation with acetonitrile containing internal standard linezolid. Insomnia patients were enrolled and treated with ZbAs, and the plasma samples were collected at baseline and end of treatment. The Pittsburgh Sleep Quality Index (PSQI) was retrieved and the concentrations of neurotransmitters were quantified. The method was successfully developed and validated. It was successfully applied to analyzing plasma samples from 51 patients, revealing a significantly increased level of 5-HT and obviously decreased levels of NE and DA after treatment, while the E kept steady against ZbAs. The PSQI significantly decreased after ZbAs treatment (21.63 ± 6.94 vs. 16.44 ± 7.17, p = 0.0006). A rapid, simple, and sensitive LC-MS/MS method for the determination of four neurotransmitters was established. ZbAs showed satisfying efficacy in treating insomnia, accompanied by obvious alterations of three neurotransmitters, which may be regarded as indicators for efficacy assessment of ZbAs.