Pharmaceutisch Weekblad

, Volume 2, Issue 1, pp 547–556 | Cite as

Photochemical decomposition of 1,4-benzodiazepines

Quantitative analyses of decomposed solutions of chlordiazepoxide and diazepam
  • P. J. G. Cornelissen
  • G. M. J. Beijersbergen van Henegouwen
Original Articles


By labelling chlordiazepoxide and diazepam with14C it was possible to follow quantitatively the photochemical decomposition of these compounds. It was found for chlordiazepoxide that the wavelength of light does not determine the character, but only the concentrations of the products formed.

On irradiation of chlordiazepoxide, dissolved in methanol or methanol-water (pH=7.4), an oxaziridine is formed, which is subsequently converted into a quinoxaline and a benzoxadiazocine derivative. However, by irradiation in the presence of glutathione, the rate of decomposition is increased and the scheme is completely changed. Instead of the quinoxaline and the benzoxadiazocine derivative, the reduced form of chlordiazepoxide and a conjugate are formed. It was established that the oxaziridine, the first photoproduct of chlordiazepoxide, reacts spontaneously with glutathione at room temperature without light.

On irradiation of diazepam, dissolved in methanolwater (pH=7.4), with light of 300 nm a benzophenone derivative is the only decomposition product, while with light of 254 nm also a quinazoline derivative is formed as a minor product. With methanol as solvent (λ=254 nm) the concentration of the products formed is strongly influenced, quinazoline derivatives become the main products and the benzophenone derivative a minor product.


Public Health Methanol Internal Medicine Glutathione Diazepam 
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Copyright information

© Bohn, Scheltema & Holkema 1980

Authors and Affiliations

  • P. J. G. Cornelissen
    • 1
  • G. M. J. Beijersbergen van Henegouwen
    • 1
  1. 1.Department of Pharmacochemistry, Subfaculty of PharmacyState University of Leiden, Gorlaeus LaboratoriesLeidenThe Netherlands

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