Effects of hydroxypropyl-beta-cyclodextrin on the chemical stability of a naphthoquinone in aqueous solutions.
2-Hydroxy-N-(3,4-dimethyl-5-isoxazolyl)-1,4-naphthoquinone-4-imine (1), an antibacterial agent, was shown to form inclusion complexes with HP-beta-CD in aqueous solution. In the present work the kinetics of 1 degradation in aqueous buffer solution was investigated as a function of pH (2.34-3.95), HP-beta-CD concentration (0%-28% (w/v)) and temperature (60-90 degrees C). A second-order derivative spectroscopic methodology was developed for the kinetic investigations. The degradation showed to follow pseudo-first-order kinetics. Also, an specific acid catalysis was found and the introduction of up to 28% (w/v) HP-beta-CD to the reaction medium did not change this kinetic behaviour. The obtained results indicated that HP-beta-CD stabilises 1 against degradation in aqueous solutions.
Linares
M S
MS
Departamento de Farmacia, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.
Longhi
M R
MR
D000073738:2-Hydroxypropyl-beta-cyclodextrin; D002021:Buffers; D002851:Chromatography, High Pressure Liquid; D003505:Cyclodextrins / Q000737:chemistry*; D004355:Drug Stability; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D009285:Naphthoquinones / Q000737:chemistry*; D015203:Reproducibility of Results; D012996:Solutions; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature; D047392:beta-Cyclodextrins
D002021:Buffers; D003505:Cyclodextrins; D009285:Naphthoquinones; D012996:Solutions; D047392:beta-Cyclodextrins; D000073738:2-Hydroxypropyl-beta-cyclodextrin