[HPLC determination of catalpol in cerebrospinal fluid of rats].

OBJECTIVE: To establish an HPLC method for determination of catalpol in CSF (cerebrospinal fluid) of rats. METHOD: Rats were intravenously injected 1.0 g x L(-1) catalpol physiological saline, and the sample of CSF from subarachnoid space of the cerebrum 40 minutes of injection. The sample of CSF from normal rats was used for blank control, the all samples were preserved in a refrigerator of - 20 degrees C, and use HPLC was employed to determine the catalpol content. The separation of catalpol was performed on Hypersil C18 reversion phase chromatographic column. The mobile phase consisted of water-acetonitrile (99.5: 0.5) with a flow rate of 1.0 mL x min(-1) and detection wavelength of 210 nm. RESULT: The linear range of catalpol in CSF was 0.5-40 mg x L(-1) (r = 0.999 7). The absolute recoveries were (90.2 +/- 1.71)%, (89.1 +/- 1.17)% and (86.9 +/- 0.98)%; and the methodological recoveries were (99.8 +/- 1.98)%, (101.1 +/- 3.04)%, (100.1 +/- 2.30)% respectively. The within-day and between-day derivation RSD were less than 4%. Catalpol was stable in a refrigerator of -20 degrees C for 15 days. CONCLUSION: The method is simple and accurate for the determination of the content of catalpol in CSF.

Distribution and metabolism of gastrodin in rat brain.

Gastrodin is the major and bioactive component in Tianma (Gastrodia elata Bl.) and has sedative, anticonvulsive and neuroprotective effects. Since little is known about its neuropharmacokinetics and brain metabolism, this study was undertaken to investigate the kinetic inter-relationship of gastrodin in rat plasma, cerebrospinal fluid (CSF) and brain microdialysate (frontal cortex, hippocampus, thalamus and cerebellum). Gastrodin was administered via the femoral vein at a dose of 200mg/kg, and blood, CSF and brain microdialysate were collected at timed intervals for the measurement of gastrodin concentrations by high-performance liquid chromatography. The samples were analyzed on a Diamonsil C18 column (5 microm, 250 mm x 4.6mm i.d.) with a mobile phase consisting of acetonitrile-water (5% acetonitrile for brain microdialysate, 2.5% acetonitrile for plasma and CSF), and detected with a UV detector at 221 nm. The distribution of gastrodin in rat showed that levels of gastrodin declined rapidly after drug administration, and the entry of gastrodin into the brain was rapid. However, the ratios of AUC(brain)/AUC(plasma) were not high. The individual ratios of the AUC in the CSF, frontal cortex, hippocampus, thalamus and cerebellum to the AUC in the plasma were 4.8+/-2.4%, 3.3+/-1.2%, 3.0+/-0.7%, 3.3+/-1.3% and 6.1+/-1.9%, respectively. The AUC in the cerebellum was significantly higher than that in other brain regions (P<0.05). The concentrations of p-hydroxybenzyl alcohol, the main metabolite of gastrodin, were very low both in the CSF and plasma.

Pharmacokinetics of Gastrodin in rat plasma and CSF after i.n. and i.v.

The pharmacokinetic behavior of Gastrodin in rat plasma and cerebrospinal fluid (CSF) after intranasal and intravenous administration (50mg kg(-1)) was investigated. Intranasal administration of Gastrodin provided a comparable AUC in CSF compared with the intravenous administration. But Gastrodin level in plasma was very low. The ratios of AUC values of intranasal to intravenous administration were 8.85% and 105.5% in plasma and CSF, respectively. The drug targeting index (DTI) was 12.34. In conclusion, intranasal administration of Gastrodin is a promising alternative to traditional administration. Olfactory mucosa did present another pathway for transport Gastrodin to the brain.