Abstract:

Introduction.  Risperidone is an antipsychotic medication from neuroleptic  group. It used to treat schizophrenia, psychotic depression, manic symptoms and autism. On chemical structure it is derivative of  benzisoxazole –  3-[2-[4-(6-fluoro-1, 2-benzisoxazol-3-yl)-1-piperidinyl] ethyl]-6, 7, 8, 9-tetrahydro-2-methyl-4H-pyrido- [1, 2-a]-pyrimidin-4-one . It is a selective monoaminergic antagonist with high affinity to 5HT 2-serotoninergic   and  D 2 dopaminergic  receptors. Aim of investigation is an elaboration of condition of quantitative and qualitative determination of risperidone using UPLC/MS/MS in internal organs. Materials and methods. Risperidone standard was received from Sigma-Aldrich (USA). Methanol was HPLC  grade (Merck). Acetonitrile and  formic acid was received from Merck  (Darmstadt,Germany).  Water was purified by Milli-Q Ultrapure Water System (Waters) and used for preparing of formic acid solution. 96 % ethanol, 25 % ammonium solution, and oxalic acid  were analytical grade. Condition of  LC-ESI-MS/MS determination. Risperidone analysis was performed on Acquity H-class UPLC system (Waters,Milford,USA) equipped with BEH C18 (2.1×50 mm, 1.7 μm) column (Waters,Milford,USA). Linear gradient elution was applied for analysis. Gradient consisted of  0.1 % formic acid in water (solvent A) and acetonitrile (solvent B). Flow rate was set to 0.5 ml/min, initial conditions were 100 % A for 1 min, followed by 40 % A for 1.5 min  and 100 % A for 1 min. MS/MS data was obtained with Xevo TQD triple quadrupole mass spectrometer detector (Waters Milford, USA). Analysis was performed in positive electrospray ionization mode. Capillary voltage was set to 2 kV, source temperature –120°C, desolvation temperature –400°C, desolvation gas flow – 800 l/h, cone gas flow – 25 l/h. MRM transition for risperidone was monitored at 411 > 191. Standart solution. Risperidone  stock solutions were prepared in methanol (1.0 mg/ml). Working standards were prepared from the stock solution with the final concentrations of 0.5; 1.0; 5,0; 10.0; 20.0; 50.0; 100.0; 500.0  and 1000/0  ng/ml. Preparing of biological sample. Risperidone was isolated from brain and liver tissues with water acidified by oxalic acid; and the extracts were purified on GraceResolv™ Silica 5g/25ml columns. An eluent was 0.5 % ammonia solution in ethanol. Samples of  biological material were investigated  after 6 or 24 hours of preparing. Results and discussion. Risperidone identified in the chromatogram for the retention time (tR = 2,91 ± 0,07 min) and the presence of signals at 411>119 m/z. Within risperidone concentrations of 0.5 to 20 ng / ml calibration plot is Y = 4.98 ·104X-1.32·104 (correlation coefficient r = 0.9998);  and the concentration range of 20 to 1000 ng/ml this dependence is Y = 5.07·104X - 1,28·104 (r = 0.99995); where Y –  area of the peak, X – risperidone concentration (ng /ml). The GraceResolv  columns allow to isolate  76.90% - 82.27% risperidone from acidic exstracts of liver and 75.3% - 81.08% –  from brain. The results of a series of parallel studies are reproducible. Conclusions.  UPLH/MS/MS method  on BEN C18  column with MRM monitoring m/z at 411> 191 has been developed for risperidone determination in biological tissues. GraceResolv ™ Silica columns isolates 76,9-82,3% of  risperidone from liver extracts and 75.3-81.1% – from brain. LOD of risperidone for liver tissue is 1 ng/g, for brain tissue is 1.4 ng/g; LOQ of this compound is 1.6 ng / g and 2 ng / g  respectively.

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