Effect of hexadecyltrimethylammonium bromide-based microemulsions on the rate of decomposition of the beta-lactam antibiotic cephaclor
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Data
1997-05-01
Autores
Oliveira, Anselmo Gomes de [UNESP]
Scarpa, Maria Virgínia
Chaimovich, Hernan
Título da Revista
ISSN da Revista
Título de Volume
Editor
Amer Pharmaceutical Assn
Resumo
Microemulsions of hexadecyltrimethylammonium bromide (HTAB)/n-butanol/hexadecane/water catalyze the intramolecular degradation of cephaclor. The rate increase is a sensitive function of the microemulsion volume fraction and salt concentration. The effects of microemulsions, analyzed quantitatively using a pseudophase ion-exchange model, assumed that the extent of ion dissociation from the microemulsions varies with volume fraction. Comparison of micellar and microemulsion effects on the same reaction shows that microemulsions are less effective catalysts. Acceleration decreased significantly by increasing the relative proportion of n-butanol ratio in microemulsions and by addition of n-butanol in HTAB micelles. Comparison of the activation parameters of the reaction in aqueous solution, microemulsions, and micelles suggests that catalysis by both aggregates is driven mainly by entropic contributions.
Descrição
Palavras-chave
Butanol, Cefaclor, Cetrimide, Hexadecane, Dissociation, Drug decomposition, Drug degradation, Drug solubility, Entropy, Ion exchange, Microemulsion, Molecular dynamics, Catalysis, Cefaclor, Cephalosporins, Cetrimonium Compounds, Emulsions, Kinetics, Thermodynamics
Como citar
Journal of Pharmaceutical Sciences. Washington: Amer Pharmaceutical Assn, v. 86, n. 5, p. 616-620, 1997.