Abstract
A sensitive and selective high performance liquid chromatography (HPLC) method has been developed for the simultaneous determination of tertatolol enantiomers in plasma and pharmaceutical formulations. Enantiomeric resolution was achieved on cellulose tris(3,5-dichlorophenylcarbamate) immobilized onto 5 µm, spherical porous silica chiral stationary phase (CSP) known as Chiralpak IC with UV detection set at 254 nm. The mobile phase which consisted of n-hexane-ethanol-triethylamine (60:40:0.1%, v/v/v) was used with a flow rate of 0.3 mL/min. Bentazepam was chosen as internal standard to guarantee a high level of quantitative performance. The assay involved the use of solid phase extraction procedures for human plasma samples prior to HPLC analysis; C
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cartridges gave good recoveries for both enantiomers without any interference. The stability of tertatolol enantiomers under different degrees of temperature was studied. The result shows that the drug was stable for at least 7 days at 70°C. The method was validated for its linearity, accuracy, precision, and robustness. The calibration curves in plasma were linear over the range of 25-1000 ng/mL for each enantiomer with a detection limit of 3 ng/mL. The mean relative standard deviation (RSD) of the results of within-day precision and accuracy of the drug were ≤2. There was no significant difference (P > 0.05) between inter-and intra-day studies for each enantiomer, which ensure the reproducibility of the assay method. The percentage recovery for both enantiomers from plasma was in the range of 91.3-98.7% at 75−800 ng/mL level for each enantiomer. The overall recoveries of tertatolol enantiomers from pharmaceutical formulation were in the range of 98-101% with %RSD ranged in 2.74-2.9%. The assay method is supposed to be suitable as therapeutic drug monitoring and chiral quality control for tertatolol formulations by HPLC.