Studies On The Determination Of Anesthetics And New Antidepressants In Human Blood And Pharmacokinetics In Rats

In recent years, the anesthetics and antidepressants are used more frequently in clinical, which play a role both in treatment and toxicity and should be paid enough attention to forensic toxicological analysis. Medical anesthetic can be divided into three categories, i.e., intravenous anesthetics, inhalation anesthetics and local anesthetics, and the former two have greater toxicity used as general anesthetics Moreover, inhalation anesthetics, mainly greenhouse gas, being harmful to the ozone layer, are less common used than intravenous anesthetics in clinical. The classic antidepressants, including monoamine oxidase inhibitor and tricyclic antidepressants, are not used often nowadays for their side effects and the feature that being easy to be abused. The new antidepressants, mainly refer to reuptake inhibitors of 5-hydroxytryptamine, reuptake inhibitors of norepinephrine, and reuptake inhibitors of both of 5-hydroxytryptamine and norepinephrine, have low toxicity and work better, but can be poisoning and even result in deadly drug-drug interaction when used improperly. Rapid and precise method should be established in forensic toxicological analysis to determine whether the case results from excess use of anesthetics or antidepressants timely and accurately. The research is presented as follows.1. A gel permeation chromatography-gas chromatography/mass spectrometry (GPC-GC/MS) method was established for the determination of propofol in human blood. GPC-GC/MS is an online system mainly used in detection of pesticide residues. It can decrease the analysis time, reduce the volume of organic solvent, simplify the operation steps, and make the analysis continuous automatically. GPC used to purification after the extraction can be combined with GC, GC/MS, HPLC and LC/MS, and the main purpose is to remove materials that may interference the determination of the target compounds, such as lipid, protein, and pigment, thus to prolong the lifetime of the chromatographic column and improve the precision and accuracy of the method. In this part, propofol was selected as the represent of medical anesthetic and thymol as internal standard. The human blood was extracted with diethyl ether, then the upper organic layer was collected after centrifugation and dried in water bath. The residue was redissolved into acetone/cyclohexane(3/7) and analyzed by GPC-GC/MS. Validation results showed that propofol was linear within the concentration range from 0.005 to 2μg/mL in blood. The linear equation was y=0.9618x+0.0033 and the correlation coefficient r2=0.9942. The precision of intra- and inter-day were all less than 17%. The recoveries were between 88.2% and 101.5%. This method is simple, accurate and sensitive, and it can be used as reference method to the determination of other anesthetics.2. A SPE-GC/MS method was developed to determinate nine new antidepressants and two metabolites, i.e., moclobemide, maprotiline, sertraline, mianserin, venlafaxine, paroxetine, melitracen, fluoxetine, citalopram, N-desmethylcitalopram, and O-desmethylvenlafaxine. By comparing the extraction efficiency of different column packing, i.e. C18 and CX ect., the C18 was finally chosen to extract the target objects in SPE. Temperature programming was adopted for the GC column, and the interface temperature was 300℃. In the optimized conditions, all the determinants were linear in the range of 50～1000 ng/mL or 100～2000 ng/mL, and the extract recoveries were above 50% except fluoxetine. The relative recoveries were between 85～115%, and the precisions were below 15% except O-desmethylvenlafaxine.3. The SPE-GC/MS method described above was used to investigate the influence of fluoxetine on the pharmacokinetics of venlafaxine in rats. The rats were divided into two groups, group I was given venlafaxine at the oral dosage of 20mg/kg, and group II 20mg/kg of venlafaxine combined with 10mg/kg fluoxetine. Blood samples were taken before and after the administration 10,20,30 minutes and 1,1.5,2.5, 3.5,5,8,12h from the orbit vain. Plasma were separated immediately by centrifugation and stored at -20℃. The samples were analyzed by GC/MS after solid phase extraction. The concentrations in plasma-time curve showed that the concentrations of group Ⅱ were higher than that of group Ⅰ. The Cmax (0.069 mg/L)、 AUC0→∞ (0.291 mg·h/L) of group Ⅱ were also greater than that of group Ⅰ, of which the Cmax and AUC0→∞ were 0.046 mg/L and 0.181 mg·h/L, respectively. The t-test indicated the Cmax and AUC0→∞ of the two groups have significant difference, which suggested fluoxetine has significant influence on the pharmacokinetics of venlafaxine in rats. As a consequence, the drug-drug interaction must be paid close attention to when fluoxetine combines with venlafaxine clinically, and the concentrations of both drugs in human beings should be monitored in order to avoid the side effects and adjust the dosage.