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 & DEG;C, injection volume of 10-& mu;L, 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 & mu;g/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.