Stability studies of clonazepam, diazepam, haloperidol, and doxepin with diverse polarities in an acidic environment.
Stability of clonazepam, diazepam, haloperidol, and doxepin was determined in acidic solutions. In addition, determination of the kinetic and thermodynamic properties of this stability was carried out. Reaction rate constants (k), half-life times (t(0.1) and t(0.5)), and activation energy (Ea) were estimated for the drugs, which differed in polarity expressed with log P values. It was observed that estimated Ea values increased from 42.13 to 125.03 kJ/mol with an increase of lipophilicity (log P) beginning from the most hydrophilic drug (clonazepam, 2.70 log P) to the most lipophilic drug (doxepin, 4.10 log P). All degradation products were studied using an HPLC/electrospray ionization-MS technique in the positive ionization mode.
Jagiellonian University, Collegium Medicum, Department of Inorganic and Analytical Chemistry, 9 Medyczna St, 30-688 Cracow, Poland.
Anna
A
Maślanka
Jan
J
Krzek
Mariusz
M
Stolarczyk
Maria
M
Walczak
Agata
A
Głogowska
D002851:Chromatography, High Pressure Liquid; D002998:Clonazepam / Q000032:analysis*; D003975:Diazepam / Q000032:analysis*; D004316:Doxepin / Q000032:analysis*; D004355:Drug Stability; D006220:Haloperidol / Q000032:analysis*; D007700:Kinetics; D021241:Spectrometry, Mass, Electrospray Ionization; D013816:Thermodynamics
D004316:Doxepin; D002998:Clonazepam; D006220:Haloperidol; D003975:Diazepam