title: Photodegradation studies of 1,4-dihydropyridine compounds by MCR analysis on UV spectral data.
abstract: BACKGROUND
  1,4-Dihydropyridines (DHPs) are well-known light-sensitive compounds. Photostability studies are necessary to ensure safety in therapy.
  
  
  METHODS
  Photodegradation experiments on 15 condensed DHP derivatives were made according to the International Conference on Harmonization rules. Degradation profiles were monitored by spectrophotometry and the data were processed by multivariate curve resolution analysis.
  
  
  RESULTS
  The analysis of the spectral data showed the formation of a single photoproduct from two DHPs, due to the aromatization of the pyridine ring. Traces of a second photoproduct were revealed in 12 DHPs and a third photoproduct was verified only in one case.
  
  
  CONCLUSIONS
  DHPs showed high stability when fluorine was in the position R1 of the phenyl ring or simultaneously present in R1 and R2 positions. In contrast, the presence of chlorine in R1 or R2 strongly increased the degradation.
authors.affiliation: Department of Pharmacy, Health & Nutritional Sciences, University of Calabria, 87036 Rende (CS), Italy.
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Ioele
authors.affiliation: Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Hacettepe University, Ankara 06100, Turkey.
authors.forename: Miyase Gözde
authors.initials: MG
authors.lastname: Gündüz
authors.affiliation: Department of Pharmacy, Health & Nutritional Sciences, University of Calabria, 87036 Rende (CS), Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: De Luca
authors.affiliation: Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Hacettepe University, Ankara 06100, Turkey.
authors.forename: Rahime
authors.initials: R
authors.lastname: Şimşek
authors.affiliation: Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Hacettepe University, Ankara 06100, Turkey.
authors.forename: Cihat
authors.initials: C
authors.lastname: Şafak
authors.affiliation: Department of Pharmacy, Health & Nutritional Sciences, University of Calabria, 87036 Rende (CS), Italy.
authors.forename: Rita
authors.initials: R
authors.lastname: Muzzalupo
authors.affiliation: Department of Pharmacy, Health & Nutritional Sciences, University of Calabria, 87036 Rende (CS), Italy.
authors.forename: Gaetano
authors.initials: G
authors.lastname: Ragno
mesh_terms: D004095:Dihydropyridines / Q000737:chemistry*; D004355:Drug Stability; D007700:Kinetics; D008027:Light; D010782:Photolysis; D013056:Spectrophotometry, Ultraviolet
chemical_list: D004095:Dihydropyridines; C038806:1,4-dihydropyridine
keywords: 1,4-dihydropyridine compounds; chemometric analysis; photodegradation; spectrophotometric analysis; stress test