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2918332 
Technical Report 
Stability of barbituric acid derivatives in aqueous solutions 
Thoma, K; Struve, M 
1985 
IPA/86/683070 
Apoth 
REF 22 
2062-2068 
IPA COPYRIGHT: ASHP The stability of barbituric acid derivatives in aqueous solutions was studied under thermal stress of 30, 40, 50 and 60DGC, utilizing spectrometry, TLC and HPLC. The shelf-life of barbital at room temperature was 67 days. A 2.8-fold decrease of the t90% of aprobarbital was observed when the temperature was increased from 40DGC to 50DGC. Solutions of derivatives with a phenyl substituent at the 5-position or with short aliphatic lateral chains had less stability. Solutions of amobarbital (I), barbital and phenobarbital (II) had slower degradation rates between pH 8.0-9.5 than at higher pH values. The thermal degradation of I at pH 10.5 was 4 times faster than at pH 7.5. Barbital and II exhibited no photolytic instability when the solutions were irradiated.