Verification Of Structure And Study On Quality Control And Pharmacokinetics In Rats Of Nicergoline

Nicergoline, (8 β )-10-methoxy-1,6-dimethylergoline-8-methanol-5-bromo-3-pyridinecarboxylate(ester),shows a -receptor blocking and vasodilating activity. The drug cause a decrease in cerebreal vascular resistance which is associated with an increase in oxygen consumption and an improvement of blood circulation and brain metabolism. Nicergoline has proved to have cerebral-anti-ischemic action,also exhibiting platelet antiaggregating and disaggregating action. It is effective clinically in chronic cerebral insufficiency and senile dementia due to insufficiency of blood in peripheral vessels.In this study, the structure of nicergoline was conformed by UV, IR, MS, NMR along with its physical-chemical property. At the same time, its purity was verified to the standard of raw drug by thermal analysis , element analysis and MS, etc. The main metabolite of nicergoline, 1-MMDL, was synthesized and identified with MS, ¹H-NMR by the author. The concent of 1-MMDL used as reference substance was 99.7% determined by HPLC with area normalization method.Since quality standard of nicergoline and its preparations have not been recorded into internal or overseas pharmacopeia yet, quality control method of nicergoline and Nicergoline for Injection were studied deeply in the paper. Nonaqueous titration was applied for the determination of content of reference substance ; RP-HPLC was developed for the assay of content and durg-related impurities in raw drugs and injections. Hypersil C₁₈ column (250 mm × 4.6 mm,10 μm) with UV detection at 287 run, and the mobile phase consisted of methyl alcohol ,phosphoric solution(30mmol·L^-1) and triethylamine (60: 40: 0.8, adjusted to pH3.5±0.1 with phosphoric acid)were used. The calibration curve was linear (r = 0.9999) within the range of 2.5 80μg · ml^-1 for nicergoline, the .detection limit was 2ng ( S/N=3 ) ; the between-day precison RSD was 0.58% (n=5) for raw drugs and 0.85% for injections, the repeatability RSD was 0.74% (n=6) for raw drugs and 0.78% for injections,and the average recovery was 99.4% for raw drugs and 99.3% for injections;the limit of drug-related impurities was 2.0% for raw drugs and 3.0% for injections. It was also examed about character,content and drug-relatedimpurities during 6 months' acceleration under 40X3 and 18 months' storage under room temperature based on quality standard already established. This method was simple, accurate and suitable for the quality control for nicergoline and nicergoline for Injection.Pharmacokinetics of Nicergolne for Injection in rats were investigated in the paper. Protein precipitation method with methyl alcohol was applied to purify plasma samples before RP-HPLC analysis.The content of 1-MMDL in plasma samples was determined on Hypersil Cig column (250x4.6mm, lOum ) with phosphoric solution (O.OSmolL"1), methyl alcohol and triethylamine (69: 31: 0.8, adjusted to pH3.5 ± 0.1 with phosphoric acid) as the mobile phase and detected at 228nm. The calibration curve was linear (r=0.9920) within the range of O^-AOmgL"1 for 1-MMDL. The detection limit was 5.0ng (S/N>3). The analytical recovery was more than 95%. within-day and between-day precision RSD were all less than 5.0% (n=5). The reliability of this method is high enough to perform quantitative analysis of 1-MMDL in plasma samples which is associated with pharmacokinetics of Nicergolne for Injection.The pharmacokinetics study of Nicergoline was performed in 8 healthy rats after intraperitoneal (i.p.) injection with single dosage by the established analytical method. The experimental data showed that Nicergoline was very rapidly hydrolyzed to 1-MMDL ,etc, by esterases after injection . Since the plasma concentration of unchanged drug was too low to be detected, I-MMDL was studied principally in the paper. The concentration-time curve of 1-MMDL in rats plasma could be fitted to two-compartment model, and the main pharmacokinetic parameters were as follows: the area under the plasma concentration-time curve (AUC) was 4.5932±2.4243 mg-L'^h, the peak plasma concentration (Cmax) was \.36\5±QA\6\mg-L'1, the peak time (Tmax) was 0.7813± 0.0884h, the absorption half life (tm, ka) was 0.1791±0.0875h , the distribution half life (t1/2, a) was 1.1819+0.5435h, the elimination half life (tm, p) was 8.2076±5.6882 h, the clearance (CL/F) was 3.0290±l.3137Lh'1kg"1, and the volume of apparent distribution (V/F) was 32.8106±26.4521Lkg"1. It was also proved that 1-MMDL appeared quickly but distributed and eliminated slowly in vivo. These findings could provide reference for clinical rational administration, moreover offer experimental data in vivo for studying other correlated dosage forms.