## 1 Introduction  
Traditional Chinese Medicine (TCM) nasal therapy (_Biliao_ in Chinese) is used to treat local or systemic diseases through intranasal administration using TCMs in the form of powders or extracts. It has a long history of well over a thousand years since first recorded in _Huangdi Neijing_ in the Warring State Period (403-221 B.C.), and is widely recorded in Chinese medical classics. It can be used to treat numerous maladies including internal, surgical, gynecological, pediatric and otolaryngologic diseases in TCM [1]. Intranasal administration has many advantages such as rapid onset of action, improved pharmacological effect, low side effect and good treatment compliance compared with oral and parenteral routes [2].  
Several clinical researches regarding TCM nasal therapy were reported [3], and there are a few studies concerning the pharmacokinetics of absorbed constituents after intranasal administration of TCM preparations or single compound isolated from TCMs [4; 5; 6]. However, these reports mainly focused on determination of the contents of one or two absorbed constituents, and there is no report about the comprehensive analysis of absorbed constituents after intranasal administration of TCM. Besides, the techniques applied in previous researches (e.g., HPLC) lacked enough sensitivity to detect the trace constituents absorbed in the biological samples such as cerebrospinal fluid (CSF).  
Asari Radix et Rhiz (AR), one of the most frequently used TCMs in TCM nasal therapy, is recorded in the Chinese Pharmacopeia as the dried roots and rhizomes of _Asarum heterotropoides_ [PERSON]. [PERSON] _var. mandshuricum_ (Maxim.) [PERSON], _A. sieboldii_ [PERSON]. _var. seoulense_ [PERSON] and _A. sieboldii_ [PERSON]. Its frequency of utilization ranks first among prescriptions to treat brain diseases [7] and second in the recipes to treat migraine [8]. It is clinically used to alleviate pain and rhinitis, mainly to treat headache. It has been reported to possess analgesic, anti-inflammatory, sedative, antispasmodic, anti-allergic, cardiovascular, antitussive, hypothermal and anticonvulsant effects [9; 10]. However, there is no report regarding the analysis of absorbed constituents of AR after intranasal administration.  
In this article, techniques with high sensitivity namely headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and high performance liquid chromatography-atmospheric pressure chemical ionization-ion trap-time of flight-multistage mass spectrometry (HPLC-APCI-IT-TOF-MS\({}^{\text{n}}\)) are employed to analyze the absorbed constituents in the plasma and CSF of rabbits after intranasal administration of AR comprehensively. HS-SPME-GC-MS is introduced to identify the volatile absorbed constituents and HPLC-APCI-IT-TOF-MS\({}^{\text{n}}\) is applied to identify the non-volatile absorbed constituents. Finally, bioactivities of the absorbed constituents related to the pharmacological effects of AR are summarized to give a better understanding of the effective substances of AR after intranasal administration. As far as we know, this is the first report to explore the absorption of AR, and comprehensively analyze the absorbed constituents after intranasal administration of a TCM.