title: A validated ultra high-pressure liquid chromatography method for separation of candesartan cilexetil impurities and its degradents in drug product.
abstract: BACKGROUND
  A selective, specific, and sensitive "Ultra High-Pressure Liquid Chromatography" (UPLC) method was developed for determination of candesartan cilexetil impurities as well asits degradent in tablet formulation.
  
  
  METHODS
  The chromatographic separation was performed on Waters Acquity UPLC system and BEH Shield RP18 column using gradient elution of mobile phase A and B. 0.01 M phosphate buffer adjusted pH 3.0 with Orthophosphoric acid was used as mobile phase A and 95% acetonitrile with 5% Milli Q Water was used as mobile phase B. Ultraviolet (UV) detection was performed at 254 nm and 210 nm, where (CDS-6), (CDS-5), (CDS-7), (Ethyl Candesartan), (Desethyl CCX), (N-Ethyl), (CCX-1), (1 N Ethyl Oxo CCX), (2 N Ethyl Oxo CCX), (2 N Ethyl) and any unknown impurity were monitored at 254 nm wavelength, and two process-related impurities, trityl alcohol and MTE impurity, were estimated at 210 nm. Candesartan cilexetil andimpurities were chromatographed with a total run time of 20 min.
  
  
  RESULTS
  Calibration showed that the response of impurity was a linear function of concentration over the range limit of quantification to 2 μg/mL (r2≥0.999) and the method was validated over this range for precision, intermediate precision, accuracy, linearity, and specificity. For the precision study, percentage relative standard deviation of each impurity was <15% (n=6).
  
  
  CONCLUSIONS
  The method was found to be precise, accurate, linear, and specific. The proposed method was successfully employed for estimation of candesartan cilexetil impurities in pharmaceutical preparations.
authors.affiliation: Dr. Reddy's Laboratories Ltd., Analytical R and D, IPDO, Bachupally, Hyderabad, India.
authors.forename: Namala Durga Atchuta
authors.initials: ND
authors.lastname: Kumar
authors.forename: K Sudhakar
authors.initials: KS
authors.lastname: Babu
authors.forename: Ullas
authors.initials: U
authors.lastname: Gosada
authors.forename: Nitish
authors.initials: N
authors.lastname: Sharma
keywords: Degradent; impurities; method validation; ultra high-pressure liquid chromatography – candesartan cilexetil