Development of RP-HPLC method for the determination of lisinopril in human saliva

Abstract

Background: Reported HPLC methods for determination of lisinopril in plasma are usually tedious requiring several extraction steps necessitating the need for new methods that address these difficulties. 

Objectives:This study was aimed at developing and validating a simple and reproducible RP-HPLC method for the determination of lisinopril in human saliva.

Methods: A blank saliva(2 mL)was spiked with 2 mL ofa solution (12.5μg ml1)of lisinopril followed by 1 mL of a solution (0.05 μg mL¹)of caffeine as internal standard (IS).The mixture was vortex mixed and centrifuged (3000rpm)for 10minutes.Aportion(0.5mL)ofthe resultant dear solution was injected into the HPLC(Agilentmodel no: 1260 infinity). A chromatogram was obtained which resolved lisinopril from caffeine(IS).The isocratic chromatographic separation was achieved using Chemsl ODS°C18(200 mm×4.6 id)analytical column.The
optimized chromatographic conditions included a mobile phase of methanol-water (80:20 v/v)containing 0.1% orthophosphoric acid,isocraticelusion mode,an injection volume of 10 μl,flow rate of 1mL min-1,a temperature of 35C and detection wavelength of 218 nm. A calibration curve of lisinopril reference standard at concentrations range of 1.0 to 50.0 μg mL¹was prepared by plotting the peak height ratios of lisinopril:IS against their corresponding concentrations.The developed method was validated with respect to precision,accuracy,
percentage recovery,limit of detection (LOD)and limit of quantitation(LOQ)according to international conference on harmonization (ICH)guidelines.

Results: The chromatographic separation was achieved in 4 minutes with lisinopril and caffeine having retention times of 1.7 and 2.6 minutes respectively. Calibration curve was linear (r =0.998) within the range of above concentrations. The precision (both inter and intraday)of the method was<1%RSD,while the accuracy expressed as percentage relative error (%Er) and % recovery were 1.20 and 99.89 %respectively.The LOD and LOQ of the method were 0.15 and 0.46ngmLI respectively. All the analytical parameters were within the normal ranges, thus reflecting good recovery and sensitivity of the method.

Conclusion:The results of this study suggest that the developed method can be employed for accurate determination oflisinopril in human saliva.