Effect Of Schisandra Sphenanthera Rehd.et Wils On Metabolism Kinetics For Olanzapine In The Rat Brains Studied By The Microdialysis

OBJECTIVESTo research the effect of schisandra sphenanthera Rehd. et Wils on metabolism kinetics for olanzapine in the rat brain studied by the microdialysis. As the studies in vitro show that the schisandra sphenanthera Rehd. et Wils can inhibit the transport function of P-gp, so this work will investigate if olanzapine's concentration in rat brains can be increased by schisandra sphenanthera Rehd. et Wils through its inhibition effect on P-gp in vivo. If that works, it can enhance the efficacy of the drug for the treatment of schizophrenia, and provide a new idea and experimental basis for the treatment of schizophrenia.METHODS1. Recovery of olanzapine in vitro and in vivoThe effect of flow rates on the recovery of olanzapine was detected by increment method and decrement method using the CMA microdialysis system, and the increment method was used to study the recovery of olanzapine on different concentrations. The stability of recovery was also detected in vitro.Healthy male SD rats(250-300g) were choosed, microdialysis guide cannulaes were fixed through brain surgery. After two days'recovery, the rats were used to study the recovery of olanzapine under different flow rates and concentrations in vivo, also the stability of recovery was detected in vivo using the CMA microdialysis system.2. Adminstration and sample collection18 healthy male SD rats (250-300g) were equally divided into three groups by completely random design. Different groups were given solvent without drug (control group),verapamil 25 mg/kg (verapamil group) and ethanol extract of schisandra sphenanthera Rehd. et Wils 30mg/kg (schisandra group) by intragatric administration for 7days, respectively. On the eighth day,20mins after drug adminstration as the same as the seventh day, the rats were given olanzapine 4 mg/kg by intragatric administration. The microdialysis system were used to begin to sample 5 minutes after administration, samples were collected every 30 mins in the first 6 hours, the every hour in the later 14 hours. All samples were stored in-70℃.3. sample analysisThe concentration of olanzapine in the brain microdialysis samples was determined by HPLC-MS/MS with columm-switching.RESULTS 1. Validation of sample analysis methodIn brain microdialysis samples, linear range was 0.085-34ng/mL for olanzapine, the inter-day and intra-day precision((RSD) were less than 13.1%. There is not complecated sample process. This methodology with high sensitivity suits for the determination of a considerable samples with small sample volumn.2. Recovery of olanzapine in vitro and in vivoThe olanzapine recovery both in vitro and in vivo decreases as the flow rates increases, and the recovery detected by increment method was as the same as which detected by decrement method in different flow rates. When the concentration changes between 20-200 ng/mL,the recovery remains the same, it will not change with the concentrations' alternation. In vitro the recovery is 21.64%, and 16.23% in vivo. Olanzapine recovery had good stability, when the flow rate is 1.5μL/min, it gives a recovery of 21.83% in vitro and 16.59% in vivo.3. Effect of schisandra sphenanthera Rehd. et Wils on metabolism kinetics for olanzapine in the rat brainAUC0→20h in rat brains(ng-h/mL) were 294.14±52.78,1377.13±409.61and 289.62±81.60 for control group, verapamil group and schisandra group, respectively. AUC0→20h in verapamil group was increased by 375.81% compared with control group,there was great difference between verapamil group and control group(P<0.05). Cmax (ng/mL) in rat brain was 93.91±35.91,217.01±83.13 and 75.25±34.74, respectively. There was not difference in statistics between control group and schisandra group, but Cmax (ng/mL) in verapmil group increased by 131.41%, and the difference between the control group and the verapamil group had the statistic significance(P<0.05).CONCLUSIONS1. Cinical dose of schisandra cann't increase the concentration of olanzapine in rat brains, it almost has no effect on the pharmacokinetics of olanzapine in the rat brain.2. When combined with classic P-gp inhibitor verapamil, the concentration of olanzapine and the AUC0→20h can be increased significantly. It proves that we could find other safe and valid P-gp inhibitors combined with drug for the treatment of schizpphrenia, so it can enhance the efficacy of the drug for the treatment of schizophrenia by increasing drug concentrations in the brains, which provides a new ideas and experimental basis for the treatment of schizophrenia.