title: The stability of quinapril hydrochloride--a mixture of amorphous and crystalline forms (QHCl-AC)--in solid phase.
abstract: The first-order rate constants and thermodynamic parameters (Ea [kJ x mole(-1)] = 139.9 for RH=0% and 133.6 for RH=76.4%; deltaH(++)[kJ x mole(-1) = 137.4 for RH=0% and 131.1 for RH=76.4%; delta(S(++) [J x (K(-1) x mole(-1)) = 35.4 for RH=0% and -207.8 for RH=76.4% for the degradation of quinapril hydrochloride--a mixture of amorphous and crystalline forms (QHCl-AC) in solid state were calculated. The effect of humidity on the stahility of QHCl-AC in the humidity range 25.0% to 76% at 363K is described by the equation ln ki = ax + b = (0.058 +/- 0.0086) x RH% - (14.19 +/- 0.50). Mechanism of degradation of QHCl-AC was investigated at 363 K (relative humidity 76.4%) and 373 K (relative humidity 0%).
authors.affiliation: Department of Pharmaceutical Chemistry, University of Medical Sciences, 6 Grunwaldzka Str., 60-780 Poznań, Poland.
authors.forename: Beata
authors.initials: B
authors.lastname: Stanisz
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003460:Crystallization; D004355:Drug Stability; D000077583:Quinapril; D044005:Tetrahydroisoquinolines / Q000737:chemistry* / Q000493:pharmacokinetics*
chemical_list: D044005:Tetrahydroisoquinolines; D000077583:Quinapril