The stability of 2-acetoxy-4-trifluoromethylbenzoic acid (Triflusal) in micellar pseudophase.
The new platelet antiaggregant Triflusal or 2-acetoxy-4-trifluoromethylbenzoic acid presents a structural analogy to acetylsalicylic acid (ASA). Alkaline hydrolysis of triflusal was studied in the presence and absence of cationic micelles of N-cetyl-N-ethyl-N,N-dimethylammonium bromide (CDEABr) at different KOH concentrations and different temperatures (25, 30, and 37 degrees C) using a spectrophotometric method. The influence of potassium bromide concentration upon alkaline hydrolysis at 25 degrees C is also discussed. At constant [KOH] pseudofirst-rate constant (k(obs)) decreased with increasing [CDEABr] at concentrations greater than the CMC and also decreased with increasing [KBr] at constant [KOH] and [CDEABr]. To explain the effect of cationic micelles of CDEABr upon alkaline hydrolysis, the pseudophase ion exchange model was used. The values of the micellar properties such as the critical micelle concentration, the degree of micellar ionization and the neutralized fraction of the head group obtained by conductivity measurements were determined previously.
Ferrit
M
M
Department of Physical Chemistry, Faculty of Pharmacy, Campus of Cartuja s/n/18071, University of Granada, Spain.
Del Valle
C
C
López
M
M
Luque
R
R
Martínez
F
F
D000465:Algorithms; D000468:Alkalies; D001965:Bromides / Q000737:chemistry; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004355:Drug Stability; D004553:Electric Conductivity; D006868:Hydrolysis; D007202:Indicators and Reagents; D007700:Kinetics; D008823:Micelles; D010975:Platelet Aggregation Inhibitors / Q000737:chemistry*; D017680:Potassium Compounds / Q000737:chemistry; D012459:Salicylates / Q000737:chemistry*; D013501:Surface-Active Agents; D013696:Temperature
D000468:Alkalies; D001965:Bromides; D007202:Indicators and Reagents; D008823:Micelles; D010975:Platelet Aggregation Inhibitors; D017680:Potassium Compounds; D012459:Salicylates; D013501:Surface-Active Agents; C016167:triflusal; C039004:potassium bromide