The Pharmacokinetics Study Of A New Chemical Antihypertensive Drug Candidate SA1501 In Rats

Objectives:SA1501 was an antihypertensive prodrug,and was metabolized as pharmacological active ingredients azilsartan and ligustrazine in rats rapidly.Azilsartan was an angiotensin(Ang)II receptor antagonist,inhibiting the action of vasoconstriction to reduce blood pressure.Ligustrazine had the action of improving blood circulation,expanding capillaries and inhibiting platelet aggregation,and was used to treat cardiovascular diseases clinically.SA1501 was an ester drugs containing of azilsartan and ligustrazine to increase therapeutic effect of cardiovascular disease.The aim of this topic was to establish rapid,effective LC-MS/MS methods used for the determination of azilsartan and hydroxyl ligustrazine.Then the method was applied to quantite azilsartan and hydroxyl ligustrazine in rat plasma,tissue,urine,feces and bile after administration of SA1501.The studies of the pharmacokinetic characteristics in rats would provide important basis for drug development and further clinical research.Methods:To establish an LC-MS/MS method for the determination of azilsartan and hydroxyl ligustrazine,and then validate the analysis method including selectivity/specificity,interference of the internal standard and the analytes,residue,the linearity and sensitivity,accuracy and precision,matrix effects and recovery,stability,dilution effects and so on.And the method of rat plasma sample was validated fully,and the other was validated partly.The LC-MS/MS methods were applied for quantitative analysis of metabolites azilsartan and hydroxyl ligustrazine in different biological samples(plasma,tissue,bile,urine,and feces)after administration,and then to study their pharmacokinetic characteristics.Results:This study established sensitive and effective LC-MS/MS methods for determination of azilsartan and hydroxyl ligustrazine in different biological samples.The quantitative range of azilsartan and hydroxyl ligustrazine were 0.01~10 ?M and 2~2000 nM,respectively.After three different dose administrations,the changes of azilsartan and hydroxyl ligustrazine were similar.The Tmax of azilsartan was 0.25~0.5 h,hydroxyl ligustrazine was at 0.0833 h,and its AUC0-t was 1.44~2.49% of azilsartan.After administration for 7 days,azilsartan and hydroxyl ligustrazine were not accumulated obviously.Compared with intravenous equimolar of azilsartan,the absolute bioavailability was 21.2%.And compared with equimolar dose of azilsartan potassium and hydroxyl ligustrazine,the relative bioavailability of azilsartan and hydroxyl ligustrazine were 83.3% and 171%,respectively.After the administration of 1.5 mg/kg SA1501 and equimolar dose of azilsartan potassium,the quantitation of azilsartan showed that distribution range of azilsartan in rats was basically identical.After administration of 0.25 h,the concentration of azilsartan in smooth and intestines reached the highest,the time of liver,muscle and uterus was 9 h,and the other tissues was 2 h.The main metabolic way of azilsartan were bile(37.9%)> urine(4.04%)> feces(?1%),and SA1501 was not detected.Conclusions:This study established and validated sensitive and reliable LC-MS/MS methods for the determination of azilsartan and hydroxyl ligustrazine with simple sample processing,which can be used for simultaneous determination of different metabolites.The methods were successfully used in pharmacokinetic study and evaluation in rats.SA1501 was metabolized as azilsartan and hydroxyl ligustrazine in rats rapidly,and the results showed after three different dose administrations,the changes of azilsartan and hydroxyl ligustrazine were similar,and were not accumulated.And after the administration of equimolar dose of azilsartan potassium and SA1501,distribution range of azilsartan was basically identical,and the excretion ratio in urine and feces is only about 4.04%(absolute bioavailability of 21.2%),so azilsartan may be eliminated through other way.