Photochemical decomposition of midazolam. III — Isolation and identification of products in aqueous solutions

Abstract

Midazolam, 8-chloro-6-(2-fluorophenyl)-1-methyl-4H-imidazo[1,5-α][1,4]benzodiazepine, decomposes photochemically in aqueous solution both under irradiation from a high-pressure mercury lamp and in normal daylight. The main decomposition product under the artificial radiation was 6-(8-chloro-l-methyl-4,5-dihydro-2,5,10 b-triaza-benzo[ e]azulen-6-ylidene)-cyclohexa-2,4-dienone, which was not present in the solution exposed to daylight. 6-Chloro-2-methyl-4(2-fluorophenyl)quinazoline was formed in both irradiation experiments and was the main decomposition product in normal daylight. Several minor products were formed in both solutions, the amounts depending on the pH of the solution. Only one decomposition product was formed in acidic solutions (pH < 2) irradiated with the high-pressure mercury lamp but numerous products were formed at higher pH.