Separation and quantitation of valacyclovir enantiomers using stability‐indicating chiral liquid chromatography method with a chiral stationary phase of amylose tris‐(3,5‐dimethylphenylcarbamate)

The present research developed and validated a new stability‐indicating technique for the stereo‐selectively enantiomers of the antiviral nucleoside analog Valacyclovir hydrochloride (VAL). The chiral separation was performed using normal‐phase high‐performance liquid chromatography (HPLC) with a chiral stationary phase consisting of amylose tris(3‐chloro‐5‐methylphenylcarbamate) and a mobile phase of “n‐hexane, methanol, ethanol, and diethylamine”, flow rate of 0.60 mL/min, column temperature of 30°C, injection volume of 10‐μL, detection wavelength of 254‐nm, and run time of 25‐min. The enantiomers (S‐enantiomer, L‐isomer, R‐enantiomer, and D‐isomer) of Valacyclovir were separated with a resolution of 4.8 and no interference. The validation parameters verified for the proposed method, linearity in a range of 0.1002–24.3486 μg/mL (0.02–4.86%) with a regression coefficient of 0.999, and the accuracy was determined with excellent recoveries ranging from 94.38%–109.97%. The concentrations established for the detection limit and quantitation limit were 0.01% and 0.02%, respectively. The forced degradation experiments were used to assess the stability‐indicating qualities. D‐Valacyclovir impurity was successfully evaluated in release and stability samples of VAL in drug substance and tablet dosage forms using the proposed normal phase chiral HPLC approach.