title: Evaluation of photostability of solid-state dimethyl 1,4-dihydro-2, 6-dimethyl-4-(2-nitro-phenyl)-3,5-pyridinedicarboxylate by using Fourier-transformed reflection-absorption infrared spectroscopy.
abstract: Effect of particle size on the photostability of dimethyl 1, 4-dihydro-2,6-dimethyl-4-(2-nitro-phenyl)-3,5-pyridinedicarboxylate (nifedipine) powder and its tablet was investigated using high-pressure liquid chromatography (HPLC) method and Fourier-transformed infrared reflection-absorption spectroscopy (FT-IR-RAS) under the non-destructive condition. The nifedipine content on the surface of the tablet was determined based on the absorbance at 1682 cm(-1) attributable to the C=O stretch vibration in FT-IR-RAS spectra before and after irradiation by fluorescent lamp. The photodegradation followed apparently the first-order kinetics for any sample. The apparent photodegradation rate constant of nifedipine powder increased with decrease of the particle size, while that of its tablet was approximately constant irrespective of particle size. Semilogarithmic plots of the apparent degradation rate constant for nifedipine tablet against the reciprocal of illuminance demonstrated a linear relationship similar to that of the Arrhenius-type behavior.
authors.affiliation: Department of Pharmaceutical Technology, Kobe Pharmaceutical University, Motoyama-Kitamachi 4-19-1, Higashi-Nada, Kobe 658-8558, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Teraoka
authors.forename: M
authors.initials: M
authors.lastname: Otsuka
authors.forename: Y
authors.initials: Y
authors.lastname: Matsuda
mesh_terms: D002121:Calcium Channel Blockers / Q000737:chemistry*; D002626:Chemistry, Pharmaceutical; D002851:Chromatography, High Pressure Liquid; D004355:Drug Stability; D008027:Light; D009543:Nifedipine / Q000737:chemistry*; D010316:Particle Size; D010777:Photochemistry; D011208:Powders; D015203:Reproducibility of Results; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013607:Tablets
chemical_list: D002121:Calcium Channel Blockers; D011208:Powders; D013607:Tablets; D009543:Nifedipine