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3041151 
Technical Report 
Stability of indomethacin in aqueous solution. Part 1. Kinetic studies and effect of solvents on the hydrolysis of indomethacin 
Chiba, K; Takahashi, M; Hayase, N; Akutsu, S; Inagaki, S 
1992 
IPA/92/1010200 
Jap 
REF 18 
43-51 
IPA COPYRIGHT: ASHP The degradation kinetics of indomethacin were studied in aqueous solution at pH 7-10 at 40-70DGC; the effects of organic solvents, propylene glycol (PG), polyethylene glycol 400 (PEG 400), and glycerin on degradation were also studied at pH 8 and 60DGC. The pseudo first-order rate constant (kobs) was independent of borate buffer concentration but the primary salt effect was positive, suggesting the role of ions in drug hydrolysis. The reaction was specific base catalyzed. Degradation reactions obeyed pseudo first-order kinetics in the presence of organic solvents. The value of kobs decreased with increased PG or PEG 400 concentration. Estimated half-lives at 60DGC and pH 8 were 5.1, 7.1, 11.9, and 1.7 h in water, 20% PG, 20% PEG 400, and 20% glycerin solutions, respectively.